# Patent

## Title
Methods and reagents to detect and characterize norwalk and related viruses

## Abstract

Double-stranded cDNA was synthesized from nucleic acid extracted from Norwalk virus purified from stool specimens of volunteers. One clone was isolated from a cDNA library constructed in a pUC-13 vector after amplification of the cDNA. The specificity of this cDNA (pUCNV-953) was shown by hybridization assays. The cDNA reacted with post (but not pre-) infection stool samples from Norwalk volunteers and with highly purified Norwalk virus, but not with other common enteric viruses such as hepatitis A virus and rotavirus. Finally, the probe detected virus in the same fractions of CsCl gradients in which viral antigen was detected using a specific Norwalk virus radioimmunoassay, and particles were detected by immune electron microscopy. Single-stranded RNA probes derived from the DNA clone after subcloning into an in vitro transcription vector were also used to show that the Norwalk virus contains a ssRNA genome of about 8 kb in size. The original clone was also used to detect additional cDNAs which represent at least 7 kb of nucleic acid of the Norwalk genome. The availability of a Norwalk-specific cDNA and the first partial genome sequence information allow rapid cloning of the entire genome and of establishment of sensitive diagnostic assays. Such assays can be based on detection of Norwalk virus nucleic acid or Norwalk viral antigen using polyclonal or monoclonal antibodies to proteins expressed from the cDNA or to synthetic peptides made based on the knowledge of the genome sequence. Assays using proteins deduced from the Norwlk virus genome and produced in expression systmes can measure antibody responses. Vaccines made by recombinant DNA technology are now feasible.

## Background
This application is a continuation of U.S. application Ser. No. 08/486,049 filed Jun. 7, 1995 issued as U.S. Pat. No. 6,572,862, which is a continuation of U.S. application Ser. No. 07/696,454 filed May 6, 1991 (now abandoned), which is a continuation in part of U.S. application Ser. No. 07/433,492 filed Nov. 8, 1989 (now abandoned), U.S. application Ser. No. 07/515,933, filed Apr. 27, 1990 (now abandoned), and U.S. application Ser. No. 07/573,509 filed Aug. 27, 1990 (now abandoned).


This invention is supported in part through grants or awards from the Food and Drug Administration and the National Institute of Health.


FIELD OF THE INVENTION
The present invention relates generally to synthesizing clones of Norwalk virus and to making probes to Norwalk and related viruses. It also relates to methods of detection and characterization of Norwalk and related viruses.
BACKGROUND OF THE INVENTION
Norwalk virus is one of the most important viral pathogens causing acute gastroenteritis, the second most common illness in the United States (Dingle et al., 1953; Kapikian and Chanock, 1985). Up to 42% of cases of viral gastroenteritis have been estimated to be caused by Norwalk or Norwalk-like viruses (Kaplan et al., 1982). Both water and foodborne transmission of Norwalk virus has been documented, and particularly large epidemic outbreaks of illness have occurred following consumption of contaminated shellfish including clams, cockles, and oysters (Murphy et al., 1979; Gunn et al., 1982; Wilson et al., 1982; Gill et al., 1983; DuPont 1986; Morse et al., 1986; Sekine et al., 1989). An increase in fish and shellfish-related food poisonings has recently been noted and attributed to increased recognition of these entities by clinicians as well as to increased consumption of seafood (Eastaugh and Shepherd, 1989). Norwalk virus was discovered in 1973. However, knowledge about the virus has remained limited because it has failed to grow in cell cultures and no suitable animal models have been found for virus cultivation. Human stool samples obtained from outbreaks and from human volunteer studies, therefore, are the only source of the virus. Still the concentration of the virus in stool is usually so low that virus detection with routine electron microscopy is not possible (Dolin et al., 1972; Kapikian et al., 1972; Thornhill et al., 1975). Current methods of Norwalk virus detection include immune electron microscopy and other immunologic methods such as radio immunoassays (RIAs) or a biotin-avidin enzyme linked immunoabsorbent assays (ELISAs) which utilize acute and convalescent phase serum from humans. To date, no hyperimmune serum from animals has been successfully prepared due either to insufficient quantities or unusual properties of the viral antigen. Preliminary biophysical characterization of virions has indicated particles contain one polypeptide (Greenberg et al., 1981), but efforts to characterize the viral genome have failed. Therefore, these viruses have remained unclassified.
CITED AND RELEVANT INFORMATION


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    3. Dolin R, Blacklow N R, DuPont H, Formal S, Buscho R F, Kasel J A, Chames R P, Hornick R, and Chanock R M. 1971. Transmission of acute infectious nonbacterial gastroenteritis to volunteers by oral administration of stool filtrates. J. Infect. Dis. 123:307-312.
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    19. Wilson R, Anderson M J, Holman R C, Gary G W, and Greenberg H B. 1982. Waterborne gastroenteritis due to the Norwalk agent: clinical and epidemiologic investigation. Am. J. Public Health 72:72-74.
    20. Hayashi Y, Ando T, Utagawa E, Sekine S, Okada S, Yabuuchi K, Miki T, and Ohashi M. 1989. Western Blot (Immunoblot) Assay, Round-Structured Virus Associated with an Acute Gastroenteritis Outbreak in Tokyo. J. Clin. Microbiol. 27:1728-1733.
    21. U.S. Pat. No. 4,358,535, issued Nov. 9, 1982, to Fahkow S and Moseley S L. Specific DNA Probes in Diagnostic Microbiology.
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SUMMARY OF THE INVENTION
It is therefore an object of the invention to characterize the Norwalk and related virus genomes by synthesizing and cloning a cDNA library.
It is an associated object of the invention to deduce amino acid sequences from the cDNA.
Another object of the invention is to develop a method of preparing polyclonal and monoclonal antibodies to the Norwalk and related viruses.
Still another object of the invention is to develop a method of making probes to detect Norwalk and related viruses.
A further object of the invention is to use the cDNA or fragments or derivatives thereof in assays to detect Norwalk and related viruses in samples suspected of containing the viruses.
A still further object of the invention is to express proteins to measure antibody responses.
A nucleotide sequence of the genome sense strand of the Norwalk virus cDNA clone according to the presently preferred embodiment of the invention intended to accomplish the foregoing objects includes the nucleotide sequence shown in Table 1. Within the nucleotide sequence are regions which encode proteins. The nucleotide sequence of the Norwalk virus genome, its fragments and derivatives are used to make diagnostic products and vaccines.
Other and still further objects, features and advantages of the present invention will be apparent from the following description of a presently preferred embodiment of the invention.



BRIEF DESCRIPTION OF THE FIGURES
FIG. 1. EM picture of Norwalk viruses after CsCl gradient purification.
FIG. 2a. Hybridization of stool samples with 32P-labeled plasmid DNA for screening positive Norwalk cDNA clones. Nucleic acids from paired stools [before (b) and after (a) infection with Norwalk virus] from two volunteers (1 and 2) were dotted on Zetabind filters. Replicate strips were prepared and hybridized at 50° C. and 65° C. with each test clone (pUC-27, pUC-593, pUC-13 and pUCNV-953). One clone (pUCNV-953) which reacted only with stool samples after (but not before) Norwalk infection was considered as a potential positive clone and was chosen for further characterization.
FIG. 2b. Dot blot hybridization of clone 32P-labeled pUCNV-953 with another 3 sets of stool samples collected at different times after infection (B=before acute phase of illness; A=acute phase of illness; P=post-acute phase of illness) of 3 volunteers. The nucleic acids were dotted directly or after treatment with RNAse or with DNAse before dotting. Double-stranded homologous cDNA (pUCNV-953) was dotted after the same treatments as the stool samples.
FIG. 3a. Dot blot hybridization of Norwalk viruses in a CsCl gradient with ssRNA probes made from pGEMNV-953. Aliquots of 50 ul from each fraction in a CsCl gradient were dotted onto a Zetabind filter. Duplicates of filters were made and hybridized with the two ssRNA probes respectively. The two strands were subsequently called cRNA (positive hybridization with the viral nucleic acid) and vRNA (no hybridization with the viral nucleic acid, data not shown). The graph shows EM counts of Norwalk viruses from each fraction of the same CsCl gradient for the dot blot hybridization. Five squares from each grid were counted and the average of the number of viral particles per square was calculated.
FIG. 4. Hybridization of Norwalk viral RNA with 32P-labeled clone pUCNV-953. Nucleic acids extracted from partially purified viruses were electrophoresed in a native agarose gel as described previously (Jiang et al., 1989). The gel was then dried at 80° C. for 1 h and hybridized with 32P-labeled pUCNV-953 insert. Lane 1, 23 S and 16 S rRNA from E. coli (Miles Laboratories Inc., Naperville, Ill. 60566), lanes 2 and 4, total nucleic acids from partially purified stool samples containing Norwalk virus, and lane 3, HAV RNA.
FIG. 5. The nucleotide sequence of the genome sense strand of the first Norwalk virus cDNA clone. The deduced amino acid sequence of a long open reading frame in this cDNA is also shown.
FIG. 6. Physical map of Norwalk virus specific clones isolated from the pUC-13 library. This map assumes the Norwalk genome is 8 kb and shows only a subset (the four largest) of  ̃100 characterized clones. cDNAs which represent at least 7 kb of nucleic acid have been identified by hybridization with pre- and post infected stool samples, or by rescreening the library with 5′-end probes of the original (pUCNV-953) and subsequent positive clones. A poly(A) tail ( ̃80 bases) is present at the 3′-end of clone pUCNV-4145. Clone pUCNV-1011 also hybridized specifically with post (but not pre-) infection stools from volunteers (see FIG. 7).
FIG. 7. Dot blot hybridization of stool samples with 32P-labeled probes representing the 3′- and 5′-end of the Norwalk viral genome. Stool samples were collected from 5 human volunteers at different times (a-e) after infection with Norwalk virus. Samples in column (a) were collected in the first 24 h post-infection, before symptoms appeared. The rest of the stool samples were collected from day 2 to day 5 post-infection. Nucleic acids were extracted and duplicate dots were immobilized on a Zetabind filter. The 3′- and 5′-end probes were derived from clones pUCNV-953 and pUCNV-1011, respectively (see FIG. 6 for description of clones).
FIG. 8. Norwalk virus encodes an RNA-directed RNA polymerase sequence motif. The deduced amino acid sequence of a portion of Norwalk virus pUCNV-4095 (NV) is compared with consensus amino acid residues thought to encode putative RNA-directed RNA polymerases of hepatitis E virus (HEV), hepatitis C virus (HCV), hepatitis A virus (HAV), Japanese encephalitis virus (JE), poliovirus (polio), foot-and-mouth disease virus (FMD), encephalomyocarditis virus (EMC), Sindbis virus (SNBV), tobacco mosaic virus (TMV), alfalfa mosaic virus (AMV), brome mosaic virus (BMV), and cowpea mosaic virus (CpMV). Sequences for viruses other than NV are from FIG. 3 of Reyes et al., Science 247:1335-1339.
FIG. 9. Three sets of primers used to amplify the Norwalk virus genome.
FIG. 10. This schematic shows the organization of Norwalk genome shown in Table 1. The features shown here are based on analyses of the nucleotide sequence of the Norwalk virus genome and the deduced amino acid sequence of proteins encoded in the genome. The genome contains 7753 nucleotides including A's at the 3′-end. Translation of the sequence predicts that the genome encodes three open reading frames (shown by the open boxes). The first open reading frame is predicted to start from an initiation codon at nucleotide 146 and it extends to nucleotide 5359 (excluding the termination codon). The second open reading frame is initiated at nucleotide 5346 and it extends to nucleotide 6935, and a third open reading frame exists between nucleotides 6938 and 7724. Based on comparisons of these predicted proteins with other proteins in the protein databank, the first open reading frame is a protein that is eventually cleaved to make at least three proteins. These three proteins include a picornavirus 2C-like protein, a 3C-like protease and an RNA-dependent RNA polymerase. The second frame encodes the capsid protein.
FIG. 11. Expression of the Norwalk virus capsid protein. Baculovirus recombinants (C-6 and C-8) that contain a subgenomic piece of Norwalk virus DNA (from nucleotides 5337 to 7724) were selected and used to infect insect (Spodoptera fugiperda) cells at a multiplicity of infection of 10 PFU/cell. After 4 days of incubation at 27° C., the infected cells were harvested and the proteins were analyzed by electrophoresis on 12% polyacrylamide gels. The proteins were visualized after staining with Coomassie blue. The Norwalk-expressed protein (highlighted by the arrow) is only seen in the recombinant-infected cells, but no in wild-type baculovirus (wt) or mock-infected insect cells.
FIG. 12. The Norwalk virus expressed protein shows immunoreactivity with sera from volunteers infected with Norwalk virus. The expressed protein shown in FIG. 11 was absorbed onto the wells of a 96-well ELISA plate and its reactivity was tested with dilutions of serum samples taken from volunteers before (pre) and three weeks after (post) infection with Norwalk virus. After an incubation at 37° C. for 2 hours, a peroxidase-conjugated goat-anti-human IgG, IgM and IgA serum was added and reactivity was subsequently observed by reading the optical density at 414 nm after addition of the substrate. The data show that post-infection sera reacted strongly with the expressed antigen at serum dilutions of 1:100 and 1:1000, and some sera were still reactive at a dilution of 1:1000.
FIG. 13. Baculovirus recombinants containing the 3′-end of the Norwalk genome produce virus-like particles in insect cells. Lysates from insect cells infected with baculovirus recombinant C-8 were analyzed by electron microscopy and shown to contain numerous virus-like particles. These particles are the same size as virus particles obtained from the stools of volunteers infected with Norwalk virus. Bar=50 nm.
FIG. 14. Norwalk virus-like particles can be purified in gradients of CsCl. Supernatants of insect cells infected with the baculovirus recombinant C-8 were processed by extraction with genetron and PEG precipitation and virus eluted from these PEG pellets was centrifuged in CsCl gradient in a SW50.1 rotor for 24 hours at 4° C. The gradient was fractionated and material in each fraction was adsorbed onto two wells of an ELISA plate. Duplicate wells were then treated either with pre- or post-infection serum, peroxidase-conjugated goat anti-human serum and substrate and the reactions were monitored by reading the OD414 nm. A peak was observed in the gradient at a density of 1.31 g/cm3 and this peak was shown to contain virus-like particles by electron microscopy. This peak also contained a major protein of an approximate molecular weight of 58,500 that comigrated with the protein expressed in the insect cells from the same baculovirus recombinant.
FIG. 15. Use of the expressed virus-like particles to measure the reactivity of pre- and post-serum samples from volunteers infected with Norwalk virus shows that most volunteers have an immune response. Volunteer 6 who did not show an immune response also did not become ill after being administered virus.



DETAILED DESCRIPTION OF THE INVENTION
It is readily apparent to one skilled in the art that various substitutions and modifications may be made to the invention disclosed herein without departing from the scope and spirit of the invention.
The term “fragment” as used herein is defined as a fragment of a genome or a subgenomic clone that is required to be expressed to produce a peptide fragment which might be able to induce a polyclonal or monoclonal antibody. It is possible a peptide of only 5 amino acids could be immunogenic but usually peptides of 15 amino acids or longer are required. This depends on the properties of the peptide and it cannot be predicted in advance.
The term “derivative” as used herein is defined as larger pieces of DNA or an additional cDNA which represents the Norwalk genome and which is detected by direct or sequential use of the original cDNA and any deduced amino acid sequences thereof. Clone pUCNV-1011, therefore, is a derivative, although it does not overlap or share sequences with the original clone. Also included within the definition of derivative are RNA counterparts of DNA fragments and DNA or cDNA fragments in which one or more bases have been substituted or to which labels and end structures have been added without affecting the reading or expression of the DNA or cDNA.
Production of Norwalk Virus for Molecular Cloning
Norwalk virus was produced by administration of safety tested Norwalk virus (8FIIa) to adult volunteers. The virus inoculum used in the volunteer study, was kindly supplied by Dr. Albert Kapikian (Laboratory of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Md.). This virus originated from an outbreak of acute gastroenteritis in Norwalk, Ohio (Dolin et al., 1971). Two ml of a 1 to 100 dilution of 8FIIa in TBS was administered orally to each individual with 80 ml of milli-Q water (Millipore, Bedford, Mass. 01730). Sodium bicarbonate solution was taken by each person 2 minutes before and 5 minutes after virus administration. The volunteer studies were approved by the Institutional Review Board for Human Research at Baylor College of Medicine, at the Methodist Hospital and at the General Clinical Research Center. The virus was administered to the volunteers in the General Clinical Research Center where the volunteers were hospitalized and under extensive medical care for 4 days. All stools were collected and kept at −70° C. for later use.
Purification of Norwalk Viruses from Stool Samples
A 10% solution of stool samples in TBS was clarified by low speed centrifugation at 3000 rpm for 15 min. The resultant supernate was then extracted two to three times with genetron in the presence of 0.5% Zwittergent 3-14 detergent (Calbiochem Corp., La Jolla, Calif.). Viruses in the aqueous phase were concentrated by pelleting at 36,000 rpm for 90 minutes through a 40% sucrose cushion in a 50.2 Ti rotor (Beckman Instruments, Inc., Palo Alto, Calif. 94304). The pellets were suspended in TBS and mixed with CsCl solution (refractive index 1.368) and centrifuged at about 35,000 rpm for about 24 h in a SW50.1 rotor (Beckman). The CsCl gradient was fractionated by bottom puncture and each fraction was monitored for virus by EM examination. The peak fractions containing Norwalk virus were pooled and CsCl in the samples was diluted with TBS and removed by pelleting the viruses at about 35,000 rpm for 1 h. The purified virus was stored at about −70° C.
Extraction of Nucleic Acids from Purified Virus
One method of extraction involved treating purified Norwalk virus from CsCl gradients with proteinase K (400 ug/ml) in proteinase K buffer (0.1 M Tris-Cl pH 7.5, 12.5 mM EDTA, 0.15 M NaCl, 1% w/v SDS) at about 37° C. for about 30 min. The samples were then extracted once with phenol-chloroform and once with chloroform. Nucleic acids in the aqueous phase were concentrated by precipitation with 2.5 volumes of ethanol in the presence of 0.2 M NaOAc followed by pelleting for 15 min in a microcentrifuge.
cDNA Synthesis and Cloning of Amplified of cDNA
One method of synthesis and cloning included denaturing nucleic acids extracted from the purified Norwalk viruses with 10 mM CH3HgOH. Then cDNA was synthesized using the cDNA synthesis kit with the supplied random hexanucleotide primer (Amersham, Arlington Heights, Ill. 60005). After the second strand synthesis, the reaction mixture was extracted once with phenol-chloroform and once with chloroform followed by ethanol precipitation. Amplification of DNA was performed using the random prime kit for DNA labeling (Promega Corp., Madison, Wis. 53711-5305). Eight cycles of denaturation (100° C. for 2 min), reannealing (2 min cooling to room temperature) and elongation (room temperature for 30 min) were performed after addition of Klenow fragment (Promega Corp.). A DNA library was constructed in pUC-13 with blunt-end ligation into the Sma I site.
Screening of the Library for Positive Clones
As one method of screening, white colonies from transformed DH5 alpha bacterial cells (BRL) were picked and both a master plate and minipreps of plasmid DNA were prepared for each clone. Clones containing inserts were identified after electrophoresis of the plasmid DNA in an agarose gel. The insert DNA in the agarose gel was cut out and labeled with 32P using random primers and Klenow DNA polymerase such as in the prime-a-gene® labeling system (Promega Corp.). Other isotopic or biochemical labels, such as enzymes, and fluorescent, chemiluminescent or bioluminescent substrates can also be used. Nucleic acids extracted from paired stool samples (before and after Norwalk infection) from two volunteers (543 and 544) were dotted onto Zetabind filters (AFM, Cuno, Meriden, Conn.). Replicate filter strips were prepared and hybridized with each labeled plasmid probe individually at 65° C. without formamide. Potential positive clones were judged by their different reactions with the pre- and post-infection stools. Clones which reacted with post (but not pre-) infection stools of volunteers were considered positive and these clones on the master plates were characterized further. Once one Norwalk clone was identified, it was used to rescreen the cDNA library to identify additional overlapping clones. Rescreening the cDNA library with these additional clones can ultimately identify clones representing the entire Norwalk virus genome.
The following examples are offered by way of illustration and are not intended to limit the invention in any manner.
EXAMPLE 1
Electron Micrograph Confirmation
To permit better diagnosis and molecular characterization of Norwalk virus, a cDNA library was derived from nucleic acid extracted from virions purified from stool samples. Norwalk virus was purified with methods used previously for hepatitis A and rotaviruses from stool samples with some modifications (Jiang et al., 1986). Basically stool samples obtained from volunteers administered Norwalk virus were treated with Genetron to remove lipid and water insoluble materials. Virus in the aqueous phase was then pelleted through a 40% sucrose cushion. The resultant pellets were resuspended, sonicated and loaded in a CsCl gradient for isopycnic centrifugation. FIG. 1 shows an electron micrograph of purified Norwalk viruses after CsCl gradient centrifugation. Approximately 109 physical particles were obtained from 500 grams of stools when the first cDNA library was made.
EXAMPLE 2
Initial cDNA Synthesis, Cloning and Screening
A cDNA library was generated from nucleic acids extracted from these purified viruses by proteinase K treatment of the samples followed by phenol-chloroform extraction and ethanol precipitation (Jiang et al., 1986; 1987). Because the nature of the viral genome was unknown, the extracted nucleic acids were denatured with methylmercuric hydroxide before cDNA synthesis. Random primed cDNA was synthesized with the Gubler-Hoffman method (cDNA synthesis system plus, Amersham) and a small amount of cDNA was obtained. Direct cloning of this small amount of cDNA was unsuccessful. Therefore, a step of amplification of the DNA was performed by synthesizing more copies of the DNA with random primers and the Klenow fragment of DNA polymerase before cloning. The procedure involved cycles of denaturation, addition of random primers and the Klenow fragment of DNA polymerase, reannealing and elongation. With this procedure, a linear incorporation of labeled nucleotides into product was observed as the number of cycles of synthesis was increased. The numbers of cycles performed were limited (<10) to avoid the synthesis of an excess of smaller fragments. In the case of Norwalk cDNA, 8 cycles of amplification were performed and approximately 2.5 ug of DNA were obtained, which was at least a 100-fold amplification of the starting template cDNA. This amplified cDNA was cloned into pUC-13 by blunt-end ligation and a positive clone (pUCNV-953) was isolated.
To obtain the positive Norwalk virus clone, minipreparations of the plasmid DNAs containing potential inserts were screened by agarose gel electrophoresis. Inserts of the larger clones in the gel were cut out and probes were made with the DNA in the gel using the prime-a-gene® labeling system (Promega Corp.). These probes were hybridized individually with paired stool samples (before and after Norwalk infection) from two volunteers (FIG. 2a). One clone (pUCNV-953) reacted with post- but not pre-infection stool samples from both volunteers.
EXAMPLE 3
Confirmation of Viral Origin of the Clone pUCNV-953
To further confirm the viral origin of the clone pUCNV-953, 6 more paired stool samples were tested and the same results were obtained. FIG. 2b shows a dot blot hybridization of the clone with stool samples collected at different times post-infection of the disease. Strong signals were observed only with stools from acute phase, but not before and after the illness. This result was consistent with previous RIA assays for viral antigen detection using convalescent sera from volunteers with Norwalk diarrhea and immune electron microscopy (IEM) studies of the samples for viral particle examination. This result also agrees with the patterns of virus shedding in stool in the course of the disease (Thornhill et al., 1975). When the clone was hybridized with fractions of a CsCl gradient from the Norwalk virus purification scheme, a correlation between hybridization and EM viral particle counts was observed (FIG. 3). The peaks of the hybridization signals and viral particle counts both were at fractions with a density of 1.38 g/cm3, which agrees with previous reports of the biophysical properties of Norwalk virus. Finally, the clone was tested by hybridization with highly purified Norwalk virus electrophoresed on an agarose gel. A single hybridization band was observed with Norwalk virus but not with HAV (FIG. 4) and rotavirus (not shown). Sequence analysis of the pUCNV-953 cDNA showed this clone is 511 bp (FIG. 5). This partial genomic cDNA encodes a potential open reading frame for which the amino acid sequence has been deduced (FIG. 5). No significant nucleotide or deduced amino acid sequence homology was found by comparison with other sequences in the Gen Bank (Molecular Biology Information Resource, Eugene Software, Baylor College of Medicine).
EXAMPLE 4
Use of Norwalk Virus cDNA to Characterize the Viral Genome
The pUCNV-953 cDNA was subcloned into the transcription vector pGEM-3Zf(+) and grown. ssRNA probes were then generated by in vitro transcription using SP6 and T7 polymerases (Promega). When two opposite sense ssRNA probes were hybridized with the viral nucleic acid separately, only one strand reacted with the virus, indicating the viral genome is single-stranded. As shown in FIG. 2b, the hybridization signals were removed by treatment of the viral nucleic acid with RNAse (but not with DNAse) before loading them onto the filters, indicating the virus genome contains ssRNA. A long open reading frame was found in one of the two strands of the inserted DNA by the computer analysis of the sequences of pUCNV-953. The ssRNA probe with the same sequence as this coding strand does not react with the viral nucleic acid, but the complementary ssRNA probe does react in the hybridization tests. Therefore, Norwalk virus contains a positive sense single-stranded RNA genome. The size of the genome of Norwalk virus was estimated to be about 8 kb based on comparisons of the migration rate of the purified viral RNA in agarose gels with molecular weight markers. This size is slightly bigger than that of the picornaviruses [HAV and poliovirus; (FIG. 4)].
The pUCNV-953 cDNA was used to rescreen a second cDNA library made as follows. A clone of the Norwalk or related virus was synthesized by isolating nucleic acid from purified Norwalk virus; cDNA was synthesized using reverse transcriptase and random primers; a second strand of DNA was synthesized from the cDNA; and at least one copy of DNA was inserted into a plasmid or a cloning and expression vector; and screening the library with the original puCNV-953 cDNA identified clones containing fragments of (or the complete) Norwalk or related genome. Alternatively at least one copy of DNA was inserted in a cloning and expression vector, such as lambda ZAPII® (Stratigene Inc.), and the cDNA library was screened to identify recombinant phage containing fragments of or the complete Norwalk or related genome. Additional cDNAs were made and found with this method. Use of these additional cDNAs to rescreen the library resulted in detection of new clones (FIG. 6). Use of the original pUCNV-953 and one additional non-overlapping cDNA (pUCNV-1011) as probes confirmed they detected virus (FIG. 7). Other overlapping cDNA (pUCNV-4145) and non-overlapping cDNA (pUCNV-4095) are useful probes to detect the Norwalk and related viruses.
Thus, the cDNA, or fragments or derivatives thereof, can be used in assays to detect the genome of Norwalk and other related viruses. The detection assays include labeled cDNA or ssRNA probes for direct detection of the Norwalk virus genome and measurement of the amount of probe binding. Alternatively, small oligonucleotide probes (10 nucleotides or greater) and polymerase chain reaction amplification are used to detect the Norwalk and related virus genomes. Expression of the open reading frame in the cDNA is used to make hyperimmune or monoclonal antibodies for use in diagnostic products and vaccines.
Using the above methodology, the nucleotide sequence in Table 1 was identified. Within that nucleotide sequence, the encoding regions for several proteins have been identified. In that sequence, the first protein is encoded by nucleotides 146 through 5339 and the amino acid sequence is shown in Table 2. This first protein is eventually cleaved to make at least three proteins including a picornavirus 2c-like protein, a 3C-like protease and an RNA-dependent RNA polymerase. The fact that this portion of the genome contains an RNA polymerase is verified by comparisons with RNA polymerase in other positive sense RNA viruses (FIG. 8).
Also in the sequence in Table 1, two other protein encoding regions were found. They are encoded by nucleotides 5346 through 6935 and nucleotides 6938 through 7724. The amino acid sequences for these two proteins are shown in Tables 3 and 4, respectively.
EXAMPLE 5
Diagnostic Assays Based on Detection of the Sequences of the Norwalk Virus Genome
Hybridization assays are the assays of choice to detect Norwalk virus because small amounts of virus are present in clinical or contaminated water and food specimens. Previously, the possibility to detect Norwalk and related nucleic acids was not possible because the genome of Norwalk virus was not known and no sequence information was available. Probes made from the Norwalk virus cDNA or primers made from the Norwalk virus genome sequence allow methods to amplify the genome for diagnostic products to be established. Probes to identify Norwalk virus alone and to identify other viruses in the Norwalk group enable development of either specific assays for Norwalk or general assays to detect sequences common to many or all of these agents.
In the past, one major difficulty encountered in RT-PCR detection of viral RNA in stool samples was that uncharacterized factor(s) are present in stools which inhibit the enzymatic activity of both reverse transcriptase and Taq polymerase (Wilde et al., J Clin Microbiol 28:1300-1307, 1990). These factor(s) were difficult to remove by routine methods of nucleic acid extraction. Techniques were developed using cetyltrimethylammonium bromide (CTAB) and oligo d(T) cellulose to specifically separate viral RNA from the inhibitory factor(s). These techniques were based on the unique properties of CTAB which selectively precipitates nucleic acid while leaving acid insoluble polysaccharide in the supernatant. The resulting nucleic acid was further purified by adsorption onto and elution from oligo d(T) cellulose. This step removes unrelated nucleic acids that lack a poly(A) tail. With this technique, Norwalk virus was detected easily by PCR in very small amounts (400 ul of a 10% suspension) of stool sample. For example, one skilled in the art will recognize that it is now possible to clone the genome of RNA viruses present in low concentrations in small amounts of stool after RT-PCR and a step of amplification of the viral RNA by RT-PCR using random primers. In some cases, RT-PCR active nucleic acids are extracted with CTAB and without oligo d(T) cellulose. In addition, now that the inhibitor(s) can be removed from stool, it will also be possible to detect and clone nucleic acids of other viruses (DNA viruses, non-poly(A) tailed RNA viruses) present in stool.
The CTAB and oligo d(T) cellulose technique of extraction followed by detection of viral RNA with RT-PCR was used on stool samples and could be used on water and food samples. Stool sample was suspended in distilled water (about 10% wt/vol) and extracted once with genetron. Viruses in the supernatant were precipitated with polyethylene glycol at a final concentration of about 8%. The viral pellets were treated with proteinase K (About 400 ug/ml) in the presence of SDS at about 37° C. for about 30 min. followed by one extraction with phenol chloroform and one with chloroform. A solution of about 5% CTAB and about 0.4M NaCl was added at a ratio of sample:CTAB=about 5:2. After incubation at about room temperature for about 15 min and at about 45° C. for about 5 min, the nucleic acids (including the viral RNA) were collected by centrifugation in a microcentrifuge for about 30 min. The resultant pellets were suspended in about 1M NaCl and extracted twice with chloroform. The viral RNA in the aqueous phase was used directly in RT-PCR reactions or further purified by adsorption/elution on oligo d(T) cellulose.
A batch method of adsorption/elution on oligo d(T) cellulose was used to purify poly(A) tailed RNA. In this procedure, nucleic acids partially purified as described above or RNA extracted directly with phenol chloroform (without CTAB treatment) were mixed with oligo d(T) cellulose (about 2-4 mg/sample) in a binding buffer (about 0.5M NaCl and 10 mM Tris, pH 7.5). The mixture was incubated at about 4° C. for about 1 hr with gentle shaking and then centrifuged for about 2 min in a microcentrifuge. The oligo d(T) cellulose pellet was washed 3-4 times with binding buffer and then the poly(A) tailed RNA was eluted with 1×TE buffer (about 1 mM Tris, 1 mM EDTA, pH 7.5). The supernate was collected following centrifugation to remove the oligo d(T) cellulose and the viral RNA in the supernate was precipitated with ethanol. The RNA obtained at this stage was basically inhibitor-free and able to be used in RT-PCR.
In preliminary experiments, Norwalk virus RNA was detected in less than 0.05 g of stool samples using the CTAB technique. A trace inhibitor activity was observed with RNA extracted with either CTAB or oligo d(T) alone, but this was easily removed by dilution (1:2) of the extracted nucleic acid before RT-PCR. Combination of the CTAB and oligo d(T) techniques resulted in obtaining high quality, inhibitor free RNA which could be used directly for RT-PCR detection and for cloning of the viral genome. With development of this method to clone from small amounts of stool, one skilled in the art will know that we will now be able to obtain cDNAs for the remainder of the genome including those representing the 5′-end of the genome.
For detection with PCR, primers based on the above nucleotide sequence of the genome were made by chemical methods. These primers include: Primer 1: CACGCGGAGGCTCTCAAT located at nucleotides 7448 to 7465; Primer 4: GGTGGCGAAGCGGCCCTC located at nucleotides 7010 to 7027; Primer 8: TCAGCAGTTATAGATATG located at nucleotides 1409 to 1426; Primer 9: ATGCTATATACATAGGTC located at nucleotides 612 to 629; Primer 16: CAACAGGTACTACGTGAC located at nucleotides 4010 to 4027; and Primer 17: TGTGGCCCAAGATTTGCT located at nucleotides 4654 to 4671. These primers have been shown to be useful to detect virus using reverse transcription and polymerase chain reaction methods (RT-PCR). FIG. 9 shows data using these primers. In primer sets 1 and 4, 8 and 9, and 16 and 17, the reverse compliments for the sequences given above for primers 1, 8, and 17 were used.
EXAMPLE 6
Preparation of Polyclonal Antibodies and Monoclonal Antibodies to Norwalk Virus Proteins
Protein(s) encoded in the cDNA fragments or derivatives thereof, is produced in a prokaryotic or eukaryotic expression system and used to immunize animals to produce polyclonal antibodies for diagnostic assays. Prokaryotic hosts may include Gram negative as well as Gram positive bacteria, such as E. coli, S. tymphimurium, Serratia marcescens, and Bacillus subtilis. Eukaryotic hosts may include yeast, insect or mammalian cells. Immunized animals may include mammals such as guinea pigs, mice, rabbits, cows, goats or horses or other non-mammalian or non-murine species such as chickens. Repeated immunization of these animals with the expressed protein mixed with an adjuvant such as Freund adjuvant to enhance stimulation of an immune response produces antibodies to the protein.
Alternatively, synthetic peptides of greater than 15 amino acids made to match the amino acid sequence deduced from the partial cDNA sequence (or from other sequences determined by sequencing additional cDNAs detected with the original or other clones) are linked to a carrier protein such as bovine serum albumin or lysozyme or cross-linked with treatment with gluteraldehyde and used to immunize animals to produce polyclonal antibodies for diagnostic tests.
The serum of animals immunized with either the expressed protein or with synthetic peptides are tested by immunologic assays such as immune electron microscopy, Western blots (immunoblots) and blocking ELISAs to demonstrate that antibodies to Norwalk and related viruses have been made. Reactivities with the expressed protein or synthetic peptides show specificity of the polyclonal sera. Reactivities with other viruses in the Norwalk group (Snow Mountain Agent, Hawaii Agent, Taunton Agent, etc.) indicate production of a reagent which recognizes cross-reacting epitopes.
Balb\c mice injected with the immunogens as described above and shown to have produced polyclonal antibodies are boosted with immunogen and then sacrificed. Their spleens are removed for fusion of splenocytes with myeloma cells to produce hybridomas. Hybridomas resulting from this fusion are screened for their reactivity with the expressed protein, the peptide and virus particles to select cells producing monoclonal antibodies to Norwalk virus. Screening of such hybridomas with Norwalk-related viruses permits identification of hybridomas secreting monoclonal antibodies to these viruses as well.
The novel features characteristic of this invention are set forth in the appended claims. The present invention is well adapted to carry out the objects and obtain the ends and advantages mentioned, as well as others inherent therein. While presently preferred embodiments of the invention have been described for the purpose of disclosure, numerous changes in the details of synthesis and use described herein will be apparent to those skilled in the art. It should be understood, however, that there is no intention to limit the invention to the specific form disclosed, but on the contrary, the intention is to cover all modifications, alternative means of synthesis and use and equivalents falling within the spirit and scope of the invention.
Development of Diagnostic Assays
Analysis of the deduced amino acid sequence of the Norwalk virus genome has shown that the Norwalk virus has the genetic organization shown in FIG. 10. Expression of regions of this genome in cell-free translation systems and in the baculovirus expression system have shown that the 5′-end of the genome encodes nonstructural proteins and the 3′-end of the genome encodes at least one structural protein. Based on this information, one can express the complete genome or subgenomic regions of the genome to produce diagnostic assays to detect viral antigens or immune responses to specific regions of the genome. This information can be used to detect the Norwalk virus, antigens or immune responses to Norwalk virus. This information also can be used to detect other similar currently uncharacterized viruses that cause gastroenteritis or possibly other diseases. Some of these viruses will be in the Caliciviridae or in the picornavirus superfamily. All of these viruses will have matching or similar genomic regions in their DNA sequences. Examples of the diagnostic assays are shown in the specific examples and figures below.
EXAMPLE 7
Development of Diagnostic Assays to Detect Nucleic Acids of Norwalk Virus or Similar Viruses by Detection of Specific Regions of the Viral Genomes Based on an Understanding of the Norwalk Genome
The genetic organization of the Norwalk virus genome allows the prediction of specific regions of the gene sequence as regions where oligonucleotide primers or probes can be developed to detect Norwalk virus sequences and common sequences of other related or similar viruses. Some of these common genome sequences will be found in viruses in the Caliciviridae or in the picornavirus superfamily. The detection can be done by standard PCR, hybridization or other gene amplification methods.
EXAMPLE 8
Development of Diagnostic Assay Using Expressed Norwalk Virus Proteins to Detect Immune Response to Norwalk Virus
Protein(s) encoded in the Norwalk virus genome or fragments or derivatives thereof is produced in a prokaryotic or eukaryotic expression system and used as antigens in diagnostic assays to detect immune responses following virus infections. Prokaryotic hosts may include Gram negative as well as Gram positive bacteria, such as Escherichia coli, Salmonella tymphimurium, Serratia marcescens, Bacillus subtilis, Staphylococcus aureus and Streptococcus sanguinis. Eukaryotic hosts may include yeast, insect or mammalian cells. Diagnostic assays may include many format such as enzyme-linked immunosorbent assays, radioimmunoassays, immunoblots or other assays. FIG. 11 shows data for a capsid protein encoded from the 3′-end of the Norwalk virus genome. It is expressed by nucleotides 5337 through 7753 of the DNA sequence shown in Table 1 and FIG. 10. This protein has an approximate molecular weight of 58,500 and is hereinafter referred to as the 58,500 mwt protein. It was produced in insect cells infected with baculovirus recombinants (C-6 and C-8). A band (see arrow in FIG. 11) representing the 58,500 mwt protein in C-6 and C-8 infected cells is not seen in insect cells infected with wild-type (WT) baculovirus or in mock infected cells. Other proteins encoded by Norwalk virus cDNA or fragments or derivatives are similarly expressed using baculovirus recombinants and other expression systems.
FIG. 12 shows data using the 58,500 mwt protein produced using the baculovirus expression system to detect immune responses before and after infection of volunteers with Norwalk virus inoculum. Antigen was put on ELISA plates and pre- and post-infection human serum was added. The data show that when an individual has had the infection, the post-serum reacts strongly to the antigen. Other proteins encoded in the Norwalk virus cDNA or fragments or derivatives thereof are similarly used to detect immune responses following Norwalk virus infection.
Some proteins have the intrinsic property of being able to form particles. The 58,500 mwt protein discussed above has that property. Particles formed from proteins are expressed in any expression system and used to produce diagnostic assays based on detection of antibody responses or immune responses. FIG. 13 shows an electron micrograph of particles produced using the baculovirus expression system from recombinants containing the 3′-end of the Norwalk genome. These particles are similar in size to the native virus particles. They are antigenic, immunoreactive and immunogenic. They differ from most of the virus particles resulting from natural infection in that many of the expressed particles lack nucleic acids.
FIG. 14 shows data on the properties of such particles following centrifugation in gradients of CsCl. The density of the particles (symbolized by closed boxes) is 1.31 g/cc which is distinct from the 1.39 g/cc density of particles purified from the original infectious Norwalk inoculum given to volunteers. The gradients were fractionated. Each fraction was put on an ELISA plate and human serum was then introduced. The open boxes show that there was no ELISA activity with the pre-infection serum. The closed diamonds show there was reactivity with the post-infection serum. Other particles made from other proteins encoded in the Norwalk virus cDNA or fragments or derivatives thereof are similarly used to detect immune responses following Norwalk virus infection.
FIG. 15 shows data using purified particles formed by the 58,500 mwt protein to detect immune responses in post-inoculation (but not pre-inoculation) serum samples of 9 volunteers infected with Norwalk virus. One of the volunteers, number 6, exhibited no symptoms of Norwalk virus infection based on monitoring clinical symptoms or measuring an immune response. Purified, expressed particles were put on ELISA plates and one pre- and one post-infection serum samples from each volunteer was added to the particles. The amount of antibody binding to the particles in each pre- and post-infection sample was measured. The data in FIG. 15 show that the expressed proteins form particles that are immunoreactive and antigenic. Other proteins encoded in the Norwalk virus cDNA or fragments or derivatives thereof are similarly used to detect immunoreactive and antigenic activity.
EXAMPLE 9
Development of Diagnostic Assays Using Expressed Norwalk Virus Expressed Antigens
Individual proteins, particles or protein aggregates formed from expression of one or more Norwalk virus genes in any prokaryotic or eukaryotic expression system are used as an immunogen or inoculate animals to produce polyclonal and monoclonal antibodies for diagnostic assays as previously described above in example 6.
Development of a Vaccine Using Norwalk Virus Expressed Antigens
EXAMPLE 10
Vaccines for Norwalk virus, the Norwalk group of viruses or other small round viruses are made from an expressed Norwalk virus protein. That expressed protein could be a Norwalk virus capsid protein expressed alone or in combination with one or more other Norwalk virus proteins or self-forming particles. For example, the particles shown in FIG. 12 were produced using the baculovirus expression system. They are used as a vaccine when expressed alone or in combination with one or more other Norwalk virus proteins. Similarly, the other proteins encoded in the Norwalk virus cDNA or fragments or derivatives thereof are used as a vaccine when expressed alone or in combination with one or more Norwalk virus proteins.
Individuals are vaccinated orally, parenterally or by a combination of both methods. For parenteral vaccination, the expressed protein is mixed with an adjuvant and administered in one or more doses in amounts and at intervals that give maximum immune response and protective immunity. Oral vaccination parallels natural infection by Norwalk virus inoculum, i.e. the individual ingests the vaccine with dechlorinated water or buffer. Oral vaccination may follow sodium bicarbonate treatment to neutralize stomach activity. For example, sodium bicarbonate solution is taken by each person 2 minutes before and 5 minutes after vaccine administration.
EXAMPLE 11
Production of a Vaccine for other Agents by Using Expressed Norwalk Virus Capsids as a Carrier or Vehicle for the Expression of other Antigens or Parts of other Antigens
Identification of the region of the genome that encodes the Norwalk virus capsid protein and that forms particles following expression (i.e., regions 5346 through 6935 and 5337 through 7724) allows genetic engineering of the cDNA that encodes the capsid protein to incorporate one or more heterologous pieces of cDNA that encode antigenic epitopes. Expression of such recombinant genes produces a recombinant capsid that is antigenic, induces antibodies, and protects against Norwalk virus and its antigens, and against the heterologous epitopes or antigens.
Alternatively, the Norwalk virus capsid protein carrier is mixed with or covalently linked to one or more heterologous protein antigens or synthetic peptides containing heterologous epitopes. This mixture and covalent linkage are antigenic, induce antibodies, and protect against Norwalk virus and its antigens, and against the heterologous epitopes or antigens.
Individuals are vaccinated using the oral and parenteral methods described above in example 10.
EXAMPLE 12
Kit
Kits for detecting immune responses to Norwalk virus are prepared by supplying in a container a protein deduced from the Norwalk virus genome shown in Table 1 or fragments or derivatives thereof and produced in an expression system. For example, the protein deduced from nucleotides 1 through 7724 the protein deduced from nucleotides 146 through 5359, the protein deduced from nucleotides 5337 through 7524, the protein deduced from nucleotides 5346 through 6935, the protein deduced from nucleotides 6938 through 7724 and any combinations thereof may be used in such kits. The kit can also include controls for false positive and false negatives, reagents and sample collection devices. The kit can be equipped to detect one sample or multiple samples.








TABLE 1





The nucleotide sequence of Norwalk virus genome.

















GGCGTCAAAA GACGTCGTTC CTACTGCTGC TAGCAGTGAA AATGCTAACA ACAATAGTAG
60



TATTAAGTCT CGTCTATTGG CGAGACTCAA GGGTTCAGGT GGGGCTACGT CCCCACCCAA
120


CTCGATAAAG ATAACCAACC AAGATATGGC TCTGGGGCTG ATTGGACAGG TCCCAGCGCC
180


AAAGGCCACA TCCGTCGATG TCCCTAAACA ACAGAGGGAT AGACCACCAC GGACTGTTGC
240


CGAAGTTCAA CAAAATTTGC GTTGCACTGA GAGACCACAA GACCAGAATG TTAAGACGTG
300


GGATGAGCTT GACCACACAA CAAAACAACA GATACTTGAT GAACACGCTG AGTGGTTTGA
360


TGCCGGTGGC TTAGGTCCAA GTACACTACC CACTAGTCAT GAACGGTACA CACATGAGAA
420


TGATGAAGGC CACCAGGTAA AGTGGTCGGC TAGGGAAGGT GTAGACCTTG GCATATCCGG
480


GCTCACGACG GTGTCTGGGC CTGAGTGGAA TATGTGCCCG CTACCACCAG TTGACCAAAG
540


GAGCACGACA CCTGCAACTG AGCCCACAAT TGGTGACATG ATCGAATTCT ATGAAGGGCA
600


CATCTATCAT TATGCTATAT ACATAGGTCA AGGCAAGACG GTGGGTGTAC ACTCCCCTCA
660


AGCAGCCTTC TCAATAACGA GGATCACCAT ACAGCCCATA TCAGCTTGGT GGCGAGTCTG
720


TTATGTCCCA CAACCAAAAC AGAGGCTCAC ATACGACCAA CTCAAAGAAT TAGAAAATGA
780


ACCATGGCCG TATGCCGCAG TCACGAACAA CTGCTTCGAA TTTTGTTGCC AGGTCATGTG
840


CTTGGAAGAT ACTTGGTTGC AAAGGAAGCT CATCTCCTCT GGCCGGTTTT ACCACCCGAC
900


CCAAGATTGG TCCCGAGACA CTCCAGAATT CCAACAAGAC AGCAAGTTAG AGATGGTTAG
960


GGATGCAGTG CTAGCCGCTA TAAATGGGTT GGTGTCGCGG CCATTTAAAG ATCTTCTGGG
1020


TAAGCTCAAA CCCTTGAACG TGCTTAACTT ACTTTCAAAC TGTGATTGGA CGTTCATGGG
1080


GGTCGTGGAG ATGGTGGTCC TCCTTTTAGA ACTCTTTGGA ATCTTTTGGA ACCCACCTGA
1140


TGTTTCCAAC TTTATAGCTT CACTCCTGCC AGATTTCCAT CTACAGGGCC CCGAGGACCT
1200


TGCCAGGGAT CTCGTGCCAA TAGTATTGGG GGGGATCGGC TTAGCCATAG GATTCACCAG
1260


AGACAAGGTA AGTAAGATGA TGAAGAATGC TGTTGATGGA CTTCGTGCGG CAACCCAGCT
1320


CGGTCAATAT GGCCTAGAAA TATTCTCATT ACTAAAGAAG TACTTCTTCG GTGGTGATCA
1380


AACAGAGAAA ACCCTAAAAG ATATTGAGTC AGCAGTTATA GATATGGAAG TACTATCATC
1440


TACATCAGTG ACTCAGCTGG TGAGGGACAA ACAGTCTGCA GGGGCTTATA TGGCCATCTT
1500


AGATAATGAA GAAGAAAAGG CAAGGAAATT ATCTGTCAGG AATGCCGACC CACACGTAGT
1560


ATCCTCTACC AATGCTCTCA TATCCCGGAT CTCAATGGCT AGGGCTGCAT TGGCCAAGGC
1620


TCAAGCTGAA ATGACCAGCA GGATGGGTCC TGTGGTCATT ATGATGTGTG GGCCCCCTGG
1680


TATAGGTAAA ACCAAGGCAG CAGAACATCT GGCTAAAGGC CTAGCCAATG AGATACGGCC
1740


TGGTGGTAAG GTTGGGCTGG TCCCACGGGA GGCAGTGGAT CATTGGGATG GATATCACGG
1800


AGAGGAAGTG ATGCTGTGGG ACGACTATGG AATGACAAAG ATACAGGAAG ACTGTAATAA
1860


ACTGCAAGCC ATAGCCGACT CAGCCCCCCT AACAGTCAAT TGTGACCGAA TAGAAAACAA
1920


GGGAATGCAA TTTGTGTCTG ATGCTATAGT CATCACCACC AATGCTCCTG GCCCAGCCCC
1980


AGTGGACTTT GTCAACCTGG GGCCTGTTTG CCGAAGGGTG GACTTGCTTG TGTATTGCAC
2040


GGCACCTGAA GTTGAACACA CGAGGAAAGT CAGTCCTGGG GACACAACTG CACTGAAAGA
2100


CTGCTTCAAG CCCGATTTCT CACATCTAAA AATGGAGTTG GCTCCCCAAG GGGGCTTTGA
2160


TAACCAAGGG AATACCCGGT TTGGTAAGGG TGTGATGAAG CCCACCACCA TAAACAGGCT
2220


GTTAATCCAG GCTGTAGCCT TGACGATGGA GAGACAGGAT GAGTTCCAAC TCCAGGGGCC
2280


TACGTATGAC TTTGATACTG ACAGAGTAGC TGCGTTCACG AGGATGCCCC GAGCCAACGG
2340


GTTGGGTCTC ATATCCATGG CCTCCCTAGG CAAAAAGCTA CGCAGTGTCA CCACTATTGA
2400


AGGATTAAAG AATGCTCTAT CAGGCTATAA AATATCAAAA TGCAGTATAC AATGGCAGTC
2460


AAGGGTGTAC ATTATAGAAT CAGATGGTGC CAGTGTACAA ATCAAAGAAG ACAAGCAAGC
2520


TTTGACCCCT CTGCAGCAGA CAATTAACAC GGCCTCACTT GCCATCACTC GACTCAAAGC
2580


AGCTAGGGCT GTGGCATACG CTTCATGTTT CCAGTCCGCC ATAACTACCA TACTACAAAT
2640


GGCGGGATCT GCGCTCGTTA TTAATCGAGC GGTCAAGCGT ATGTTTGGTA CCCGTACAGC
2700


AGCCATGGCA TTAGAAGGAC CTGGGAAAGA ACATAATTGC AGGGTCCATA AGGCTAAGGA
2760


AGCTGGAAAG GGGCCCATAG GTCATGATGA CATGGTAGAA AGGTTTGGCC TATGTGAAAC
2820


TGAAGAGGAG GAGAGTGAGG ACCAAATTCA AATGGTACCA AGTGATGCCG TCCCAGAAGG
2880


AAAGAACAAA GGCAAGACCA AAAAGGGACG TGGTCGCAAA AATAACTATA ATGCATTCTC
2940


TCGCCGTGGT CTGAGTGATG AAGAATATGA AGAGTACAAA AAGATCAGAG AAGAAAAGAA
3000


TGGCAATTAT AGTATACAAG AATACTTGGA GGACCGCCAA CGATATGAGG AAGAATTAGC
3060


AGAGGTACAG GCAGGTGGTG ATGGTGGCAT AGGAGAAACT GAAATGGAAA TCCGTCACAG
3120


GGTCTTCTAT AAATCCAAGA GTAAGAAACA CCAACAAGAG CAACGGCGAC AACTTGGTCT
3180


AGTGACTGGA TCAGACATCA GAAAACGTAA GCCCATTGAC TGGACCCCGC CAAAGAATGA
3240


ATGGGCAGAT GATGACAGAG AGGTGGATTA TAATGAAAAG ATCAATTTTG AAGCTCCCCC
3300


GACACTATGG AGCCGAGTCA CAAAGTTTGG ATCAGGATGG GGCTTTTGGG TCAGCCGGAC
3360


AGTGTTCATC ACAACCACAC ATGTAGTGCC AACTGGTGTG AAAGAATTCT TTGGTGAGCC
3420


CCTATCTAGT ATAGCAATCC ACCAAGCAGG TGAGTTCACA CAATTCAGGT TCTCAAAGAA
3480


AATGGGCCCT GACTTGACAG GTATGGTCCT TGAAGAAGGT TGCCCTGAAG GGACAGTCTG
3540


CTCAGTCCTA ATTAAACGGG ATTCGGGTGA ACTAGTTCCG CTAGCCGTCC GTATGGGGGC
3600


TATTGCCTCC ATGAGGATAC AGGGTCGGCT TGTCCATGGC CAATCAGGGA TGTTACTGAC
3660


AGGGGCCAAT GCAAAGGGGA TGGATCTTGG CACTATACCA GGAGACTGCG GGGCACCATA
3720


CGTCCACAAG CGCGGGAATG ACTGGGTTGT GTGTGGAGTC CACGCTGCAG CCACAAAGTC
3780


AGGCAACACC GTGGTCTGCG CTGTACAGGC TGGAGAGGGC GAAACCGCAC TAGAAGGTGG
3840


AGACAAGGGG CATTATGCCG GCCACGAGAT TGTGAGGTAT GGAAGTGGCC CAGCACTGTC
3900


AACTAAAACA AAATTCTGGA GGTCCTCCCC AGAACCACTG CCCCCCGGAG TATATGAGCC
3960


AGCATACCTG GGGGGCAAGG ACCCCGGTGT ACAGAATGGC CCATCCCTAC AACAGGTACT
4020


ACGTGACCAA CTGAAACCCT TTGCGGACCC CCGCGGCCGC ATGCCTGAGC CTGGCCTACT
4080


GGAGGCTGCG GTTGAGACTG TAACATCCAT GTTAGAACAG ACAATGGATA CCCCAAGCCC
4140


GTGGTCTTAC GCTGATGCCT GCCAATCTCT TGACAAAACT ACTAGTTCGG GGTACCCTCA
4200


CCATAAAAGG AAGAATGATG ATTGGAATGG CACCAGCTTC GTTGGAGAGC TCGGTGAGCA
4260


AGCTGCACAC GCCAACAATA TGTATGAGAA TGCTAAACAT ATGAAACCCA TTTACACTGC
4320


AGCCTTAAAA GATGAACTAG TCAAGCCAGA AAAGATTTAT CAAAAAGTCA AGAAGCGTCT
4380


ACTATGGGGC GCCGATCTCG GAACAGTGGT CAGGGCCGCC CGGGCTTTTG GCCCCATTTG
4440


TGACGCTATA AAATCACATG TCATCAAATT GCCAATAAAA GTTGGCATGA ACACAATAGA
4500


AGATGGCCCC CTCATCTATG CTGAGCATGC TAAATATAAG AATCATTTTG ATGCAGATTA
4560


TACAGCATGG GACTCAACAC AAAATAGACA AATTATGACA GAATCCTTCT CCATTATGTC
4620


GCGCCTTACG GCCTCACCAG AATTGGCCGA GGTTGTGGCC CAAGATTTGC TAGCACCATC
4680


TGAGATGGAT GTAGGTGATT ATGTCATCAG GGTCAAAGAG GGGCTGCCAT CTGGATTCCC
4740


ATGTACTTCC CAGGTGAACA GCATAAATCA CTGGATAATT ACTCTCTGTG CACTGTCTGA
4800


GGCCACTGGT TTATCACCTG ATGTGGTGCA ATCCATGTCA TATTTCTCAT TTTATGGTGA
4860


TGATGAGATT GTGTCAACTG ACATAGATTT TGACCCAGCC CGCCTCACTC AAATTCTCAA
4920


GGAATATGGC CTCAAACCAA CAAGGCCTGA CAAAACAGAA GGACCAATAC AAGTGAGGAA
4980


AAATGTGGAT GGACTGGTCT TCTTGCGGCG CACCATTTCC CGTGATGCGG CAGGGTTCCA
5040


AGGCAGGTTA GATAGGGCTT CGATTGAACG CCAAATCTTC TGGACCCGCG GGCCCAATCA
5100


TTCAGATCCA TCAGAGACTC TAGTGCCACA CACTCAAAGA AAAATACAGT TGATTTCACT
5160


TCTAGGGGAA GCTTCACTCC ATGGTGAGAA ATTTTACAGA AAGATTTCCA GCAAGGTCAT
5220


ACATGAAATC AAGACTGGTG GATTGGAAAT GTATGTCCCA GGATGGCAGG CCATGTTCCG
5280


CTGGATGCGC TTCCATGACC TCGGATTGTG GACAGGAGAT CGCGATCTTC TGCCCGAATT
5340


CGTAAATGAT GATGGCGTCT AAGGACGCTA CATCAAGCGT GGATGGCGCT AGTGGCGCTG
5400


GTCAGTTGGT ACCGGAGGTT AATGCTTCTG ACCCTCTTGC AATGGATCCT GTAGCAGGTT
5460


CTTCGACAGC AGTCGCGACT GCTGGACAAG TTAATCCTAT TGATCCCTGG ATAATTAATA
5520


ATTTTGTGCA AGCCCCCCAA GGTGAATTTA CTATTTCCCC AAATAATACC CCCGGTGATG
5580


TTTTGTTTGA TTTGAGTTTG GGTCCCCATC TTAATCCTTT CTTGCTCCAT CTATCACAAA
5640


TGTATAATGG TTGGGTTGGT AACATGAGAG TCAGGATTAT GCTAGCTGGT AATGCCTTTA
5700


CTGCGGGGAA GATAATAGTT TCCTGCATAC CCCCTGGTTT TGGTTCACAT AATCTTACTA
5760


TAGCACAAGC AACTCTCTTT CCACATGTGA TTGCTGATGT TAGGACTCTA GACCCCATTG
5820


AGGTGCCTTT GGAAGATGTT AGGAATGTTC TCTTTCATAA TAATGATAGA AATCAACAAA
5880


CCATGCGCCT TGTGTGCATG CTGTACACCC CCCTCCGCAC TGGTGGTGGT ACTGGTGATT
5940


CTTTTGTAGT TGCAGGGCGA GTTATGACTT GCCCCAGTCC TGATTTTAAT TTCTTGTTTT
6000


TAGTCCCTCC TACGGTGGAG CAGAAAACCA GGCCCTTCAC ACTCCCAAAT CTGCCATTGA
6060


GTTCTCTGTC TAACTCACGT GCCCCTCTCC CAATCAGTAG TATGGGCATT TCCCCAGACA
6120


ATGTCCAGAG TGTGCAGTTC CAAAATGGTC GGTGTACTCT GGATGGCCGC CTGGTTGGCA
6180


CCACCCCAGT TTCATTGTCA CATGTTGCCA AGATAAGAGG GACCTCCAAT GGCACTGTAA
6240


TCAACCTTAC TGAATTGGAT GGCACACCCT TTCACCCTTT TGAGGGCCCT GCCCCCATTG
6300


GGTTTCCAGA CCTCGGTGGT TGTGATTGGC ATATCAATAT GACACAGTTT GGCCATTCTA
6360


GCCAGACCCA GTATGATGTA GACACCACCC CTGACACTTT TGTCCCCCAT CTTGGTTCAA
6420


TTCAGGCAAA TGGCATTGGC AGTGGTAATT ATGTTGGTGT TCTTAGCTGG ATTTCCCCCC
6480


CATCACACCC GTCTGGCTCC CAAGTTGACC TTTGGAAGAT CCCCAATTAT GGGTCAAGTA
6540


TTACGGAGGC AACACATCTA GCCCCTTCTG TATACCCCCC TGGTTTCGGA GAGGTATTGG
6600


TCTTTTTCAT GTCAAAAATG CCAGGTCCTG GTGCTTATAA TTTGCCCTGT CTATTACCAC
6660


AAGAGTACAT TTCACATCTT CCTAGTGAAC AAGCCCCTAC TGTAGGTGAG GCTGCCCTGC
6720


TCCACTATGT TGACCCTGAT ACCGGTCGGA ATCTTGGGGA ATTCAAAGCA TACCCTGATG
6780


GTTTCCTCAC TTGTGTCCCC AATGGGGCTA GCTCGGGTCC ACAACAGCTG CCGATCAATG
6840


GGGTCTTTGT CTTTGTTTCA TGGGTGTCCA GATTTTATCA ATTAAAGCCT GTGGGAACTG
6900


CCAGCTCGGC AAGAGGTAGG CTTGGTCTGC GCCGATAATG GCCCAAGCCA TAATTGGTGC
6960


AATTGCTGCT TCCACAGCAG GTAGTGCTCT GGGAGCGGGC ATACAGGTTG GTGGCGAAGC
7020


GGCCCTCCAA AGCCAAAGGT ATCAACAAAA TTTGCAACTG CAAGAAAATT CTTTTAAACA
7080


TGACAGGGAA ATGATTGGGT ATCAGGTTGA AGCTTCAAAT CAATTATTGG CTAAAAATTT
7140


GGCAACTAGA TATTCACTCC TCCGTGCTGG GGGTTTGACC AGTGCTGATG CAGCAAGATC
7200


TGTGGCAGGA GCTCCAGTCA CCCGCATTGT AGATTGGAAT GGCGTGAGAG TGTCTGCTCC
7260


CGAGTCCTCT GCTACCACAT TGAGATCCGG TGGCTTCATG TGAGTTCCCA TACCATTTGC
7320


CTCTAAGCAA AAACAGGTTC AATCATCTGG TATTAGTAAT CCAAATTATT CCCCTTCATC
7380


CATTTCTCGA ACCACTAGTT GGGTCGAGTC ACAAAACTCA TCGAGATTTG GAAATCTTTC
7440


TCCATACCAC GCGGAGGCTC TCAATACAGT GTGGTTGACT CCACCCGGTT CAACAGCCTC
7500


TTCTACACTG TCTTCTGTGC CACGTGGTTA TTTCAATACA GACAGGTTGC CATTATTCGC
7560


AAATAATAGG CGATGATGTT GTAATATGAA ATGTGGGCAT CATATTCATT TAATTAGGTT
7620


TAATTAGGTT TAATTTGATG TTAAAAAAAA AAAAAAAAAA AAAAAAAAAA AAAAAAAAAA
7680


AAAAAAAAAA AAAAAAAAAA AAAAAAAAAA AAAAAAAAAA AAAA
7724
















TABLE 2





The amino acid sequence deduced from nucleotides 146 through



5359 of the Norwalk virus genome shown in Table 1.

















CTCGATAAAG ATAACCAACC AAGAT ATG GCT CTG GGG CTG ATT GGA CAG GTC
172



                            Met Ala Leu Gly Leu Ile Gly Gln Val



                              1               5



CCA GCG CCA AAG GCC ACA TCC GTC GAT GTC CCT AAA CAA CAG AGG GAT
220


Pro Ala Pro Lys Ala Thr Ser Val Asp Val Pro Lys Gln Gln Arg Asp



 10                   15                  20                  25



AGA CCA CCA CGG ACT GTT GCC GAA GTT CAA CAA AAT TTG CGT TGG ACT
268


Arg Pro Pro Arg Thr Val Ala Glu Val Gln Gln Asn Leu Arg Trp Thr



                 30                  35                  40



GAG AGA CCA CAA GAC CAG AAT GTT AAG ACG TGG GAT GAG CTT GAC CAC
316


Glu Arg Pro Gln Asp Gln Asn Val Lys Thr Trp Asp Glu Leu Asp His



             45                  50                  55



ACA ACA AAA CAA CAG ATA CTT GAT GAA CAC GCT GAG TGG TTT GAT GCC
364


Thr Thr Lys Gln Gln Ile Leu Asp Glu His Ala Glu Trp Phe Asp Ala



         60                  65                  70



GGT GGC TTA GGT CCA AGT ACA CTA CCC ACT AGT CAT GAA CGG TAC ACA
412


Gly Gly Leu Gly Pro Ser Thr Leu Pro Thr Ser His Glu Arg Tyr Thr



     75                  80                  85



CAT GAG AAT GAT GAA GGC CAC CAG GTA AAG TGG TCG GCT AGG GAA GGT
460


His Glu Asn Asp Glu Gly His Gln Val Lys Trp Ser Ala Arg Glu Gly



 90                  95                 100                 105



GTA GAC CTT GGC ATA TCC GGG CTC ACG ACG GTG TCT GGG CCT GAG TGG
508


Val Asp Leu Gly Ile Ser Gly Leu Thr Thr Val Ser Gly Pro Glu Trp



                110                 115                 120



AAT ATG TGC CCG CTA CCA CCA GTT GAC CAA AGG AGC ACG ACA CCT GCA
556


Asn Met Cys Pro Leu Pro Pro Val Asp Gln Arg Ser Thr Thr Pro Ala



            125                 130                 135



ACT GAG CCC ACA ATT GGT GAC ATG ATC GAA TTC TAT GAA GGG CAC ATC
604


Thr Glu Pro Thr Ile Gly Asp Met Ile Glu Phe Tyr Glu Gly His Ile



        140                 145                 150



TAT CAT TAT GCT ATA TAC ATA GGT CAA GGC AAG ACG GTG GGT GTA CAC
652


Tyr His Tyr Ala Ile Tyr Ile Gly Gln Gly Lys Thr Val Gly Val His



    155                 160                 165



TCC CCT CAA GCA CCC TTC TCA ATA ACG AGG ATC ACC ATA CAG CCC ATA
700


Ser Pro Gln Ala Ala Phe Ser Ile Thr Arg Ile Thr Ile Gln Pro Ile



170                 175                 180                 185



TCA GCT TGG TGG CGA GTC TGT TAT GTC CCA CAA CCA AAA CAG AGG CTC
748


Ser Ala Trp Trp Arg Val Cys Tyr Val Pro Gln Pro Lye Gln Arg Leu



                190                 195                 200



ACA TAC GAC CAA CTC AAA GAA TTA GAA AAT GAA CCA TGG CCG TAT GCC
796


Thr Tyr Asp Gln Leu Lys Glu Leu Glu Asn Glu Pro Trp Pro Tyr Ala



            205                 210                 215



GCA GTC ACG AAC AAC TGC TTC GAA TTT TGT TGC CAG GTC ATG TGC TTG
844


Ala Val Thr Asn Asn Cys Phe Glu Phe Cys Cys Gln Val Met Cys Leu



        220                 225                 230



GAA GAT ACT TGG TTG CAA AGG AAG CTC ATC TCC TCT GGC CGG TTT TAC
892


Glu Asp Thr Trp Leu Gln Arg Lye Leu Ile Ser Ser Gly Arg Phe Tyr



    235                 240                 245



CAC CCG ACC CAA GAT TGG TCC CGA GAC ACT CCA GAA TTC CAA CAA GAC
940


His Pro Thr Gln Asp Trp Ser Arg Asp Thr Pro Glu Phe Gln Gln Asp



250                 255                 260                 265



AGC AAG TTA GAG ATG GTT AGG GAT GCA GTG CTA GCC GCT ATA AAT GGG
988


Ser Lys Leu Glu Met Val Arg Asp Ala Val Leu Ala Ala Ile Asn Gly



                270                 275                 280



TTG GTG TCG CGG CCA TTT AAA GAT CTT CTG GGT AAG CTC AAA CCC TTG
1036


Leu Val Ser Arg Pro Phe Lys Asp Leu Leu Gly Lys Leu Lys Pro Leu



            285                 290                 295



AAC GTG CTT AAC TTA CTT TCA AAC TGT GAT TGG ACG TTC ATG GGG GTC
1084


Asn Val Leu Asn Leu Leu Ser Asn Cys Asp Trp Thr Phe Met Gly Val



        300                 305                 310



GTG GAG ATG GTG GTC CTC CTT TTA GAA CTC TTT GGA ATC TTT TGG AAC
1132


Val Glu Met Val Val Leu Leu Leu Glu Leu Phe Gly Ile Phe Trp Asn



    315                 320                 325



CCA CCT GAT GTT TCC AAC TTT ATA GCT TCA CTC CTG CCA GAT TTC CAT
1180


Pro Pro Asp Val Ser Asn Phe Ile Ala Ser Leu Leu Pro Asp Phe His



330                 335                 340                 345



CTA CAG GGC CCC GAG GAC CTT GCC AGG GAT CTC GTG CCA ATA GTA TTG
1228


Leu Gln Gly Pro Glu Asp Leu Ala Arg Asp Leu Val Pro Ile Val Leu



                350                 355                 360



GGG GGG ATC GGC TTA GCC ATA GGA TTC ACC AGA GAC AAG GTA AGT AAG
1276


Gly Gly Ile Gly Leu Ala Ile Gly Phe Thr Arg Asp Lys Val Ser Lys



            365                 370                 375



ATG ATG AAG AAT GCT GTT GAT GGA CTT CGT GCG GCA ACC CAG CTC GGT
1324


Met Met Lys Asn Ala Val Asp Gly Leu Arg Ala Ala Thr Gln Leu Gly



        380                 385                 390



CAA TAT GGC CTA GAA ATA TTC TCA TTA CTA AAG AAG TAC TTC TTC GGT
1372


Gln Tyr Gly Leu Glu Ile Phe Ser Leu Leu Lys Lys Tyr Phe Phe Gly



    395                 400                 405



GGT GAT CAA ACA GAG AAA ACC CTA AAA GAT ATT GAG TCA GCA GTT ATA
1420


Gly Asp Gln Thr Glu Lys Thr Leu Lys Asp Ile Glu Ser Ala Val Ile



410                 415                 420                 425



GAT ATG GAA GTA GTA TCA TCT ACA TCA GTG ACT CAG CTC GTG AGG GAC
1468


Asp Met Glu Val Leu Set Ser Thr Set Val Thr Gln Leu Val Arg Asp



                430                 435                 440



AAA CAG TCT GCA CGG GCT TAT ATG GCC ATC TAA GAT AAT GAA GAA GAA
1516


Lys Gln Ser Ala Arg Ala Tyr Met Ala Ile Leu Asp Asn Glu Glu Glu



            445                 450                 455



AAG GCA AGG AAA TTA TCT GTC AGG AAT GCC GAC CCA CAC GTA GTA TCC
1564


Lys Ala Arg Lys Leu Ser Val Arg Asn Ala Asp Pro His Val Val Ser



        460                 465                 470



TCT ACC AAT GCT CTC ATA TCC CGG ATC TCA ATG GCT AGG GCT GCA TTG
1612


Ser Thr Asn Ala Leu lIe Ser Arg Ile Ser Met Ala Arg Ala Ala Leu



    475                 480                 485



GCC AAG GCT CAA GCT GAA ATG ACC AGC AGG ATG CGT CCT GTG GTC ATT
1660


Ala Lys Ala Gln Ala Glu Met Thr Ser Arg Met Arg Pro Val Val Ile



490                 495                 500                 505



ATG ATG TGT GGG CCC CCT GGT ATA GGT AAA ACC AAG GCA GCA GAA CAT
1708


Met Met Cys Gly Pro Pro Gly Ile Gly Lys Thr Lys Ala Ala Glu His



                510                 515                 520



CTG GCT AAA CGC CTA GCC AAT GAG ATA CGG CCT GGT GGT AAG GTT GGG
1756


Leu Ala Lys Arg Leu Ala Asn Glu Ile Arg Pro Gly Gly Lys Val Gly



            525                 530                 535



CTG GTC CCA CGG GAG GCA GTG GAT CAT TGG GAT GGA TAT CAC GGA GAG
1804


Leu Val Pro Arg Glu Ala Val Asp His Trp Asp Gly Tyr Ile Gly Glu



        540                 545                 550



GAA GTG ATG CTG TGG GAC GAG TAT GGA ATG ACA AAG ATA CAG GAA GAC
1852


Glu Val Met Leu Trp Asp Asp Tyr Gly Met Thr Lys Ile Gln Glu Asp



    555                 560                 565



TGT AAT AAA CTG CAA GCC ATA GCC GAC TCA GCC CCC CTA ACA CTC AAT
1900


Cys Asn Lys Leu Gln Ala Ile Ala Asp Ser Ala Pro Leu Thr Leu Asn



570                 575                 580                 585



TGT GAC CGA ATA GAA AAC AAG GGA ATG CAA TTT GTG TGT GAT GCT ATA
1948


Cys Asp Arg Ile Glu Asn Lys Gly Met Gln Phe Val Ser Asp Ala Ile



                590                 595                 600



GTC ATC ACC ACC AAT GCT CCT GGC CCA GCC CCA GTG GAC TTT GTC AAC
1996


Val Ile Thr Thr Asn Ala Pro Gly Pro Ala Pro Val Asp Phe Val Asn



            605                 610                 615



CTC GGG CCT GTT TGC CGA AGG GTG GAC TTC CTT GTG TAT TGC ACG GCA
2044


Leu Gly Pro Val Cys Arg Arg Val Asp Phe Leu Val Tyr Cys Thr Ala



        620                 625                 630



CGT GAA GTT GAA CAC ACG AGG AAA GTC AGT CCT GGG GAC ACA ACT GCA
2092


Pro Glu Val Glu His Thr Arg Lys Val Ser Pro Gly Asp Thr Thr Ala



    635                 640                 645



CTG AAA GAC TGC TTC AAG CCC GAT TTC TCA CAT CTA AAA ATG GAG TTG
2140


Leu Lys Asp Cys Phe Lys Pro Asp Phe Ser His Leu Lys Met Glu Leu



650                 655                 660                 665



GCT CCC CAA GGG GGC TTT GAT AAC CAA GGG AAT ACC CCG TTT GGT AAG
2188


Ala Pro Gln Gly Gly Phe Asp Asn Gln Gly Asn Thr Pro Phe Gly Lys



                670                 675                 680



GGT GTG ATG AAG CCC ACC ACC ATA AAC AGG CTG TTA ATC CAG GCT GTA
2236


Gly Val Met Lys Pro Thr Thr Ile Asn Arg Leu Leu Ile Gln Ala Val



            685                 690                 695



GCC TTG ACG ATG GAG AGA CAG GAT GAG TTC CAA CTC CAG GGG CCT ACG
2284


Ala Leu Thr Met Glu Arg Gln Asp Glu Phe Gln Leu Gln Gly Pro Thr



        700                 705                 710



TAT GAC TTT GAT ACT GAC AGA GTA GCT GCG TTC ACG AGG ATG GCC CGA
2332


Tyr Asp Phe Asp Thr Asp Arg Val Ala Ala Phe Thr Arg Met Ala Arg



    715                 720                 725



GCC AAC GGG TTG GGT CTC ATA TCC ATG GCC TCC CTA GGC AAA AAG CTA
2380


Ala Asn Gly Leu Gly Leu Ile Ser Met Ala Ser Leu Gly Lys Lys Leu



730                 735                 740                 745



CGC AGT GTC ACC ACT ATT GAA GGA TTA AAG AAT GCT CTA TCA GGC TAT
2428


Arg Ser Val Thr Thr Ile Glu Gly Leu Lys Asn Ala Leu Ser Gly Tyr



                750                 755                 760



AAA ATA TCA AAA TGC AGT ATA CAA TGG CAG TCA AGG GTG TAC ATT ATA
2476


Lys Ile Ser Lys Cys Ser Ile Gln Trp Gln Ser Arg Val Tyr Ile Ile



            765                 770                 775



GAA TCA GAT GGT GCC AGT GTA CAA ATC AAA GAA GAC AAG CAA GCT TTG
2524


Glu Ser Asp Gly Ala Ser Val Gln Ile Lys Glu Asp Lys Gln Ala Leu



        780                 785                 790



ACC CCT CTG CAG CAG ACA ATT AAC ACG GCC TCA CTT GCC ATC ACT CGA
2572


Thr Pro Leu Gln Gln Thr Ile Asn Thr Ala Ser Leu Ala Ile Thr Arg



    795                 800                 805



CTC AAA GCA GCT AGG GCT GTG GCA TAC GCT TCA TGT TTC CAG TCC GCC
2620


Leu Lys Ala Ala Arg Ala Val Ala Tyr Ala Ser Cys Phe Gln Ser Ala



810                 815                 820                 825



ATA ACT ACC ATA CTA CAA ATG GCG GGA TCT GCG CTC GTT ATT AAT CGA
2668


Ile Thr Thr Ile Leu Gln Met Ala Gly Ser Ala Leu Val Ile Asn Arg



                830                  835                 840



GCG GTC AAG CGT ATG TTT GGT ACC CGT ACA GCA GCC ATG GCA TTA GAA
2716


Ala Val Lys Arg Met Phe Gly Thr Arg Thr Ala Ala Met Ala Leu Glu



            845                 850                 855



GGA CCT GGG AAA GAA CAT AAT TGC AGG GTC CAT AAG GCT AAG GAA GCT
2764


Gly Pro Gly Lys Glu His Asn Cys Arg Val His Lys Ala Lys Glu Ala



        860                 865                 870



GGA AAG GGG CCC ATA GGT CAT GAT GAC ATG GTA GAA AGG TTT GCC CTA
2812


Gly Lys Gly Pro Ile Gly His Asp Asp Met Val Glu Arg Phe Gly Leu



    875                 880                 885



TGT GAA ACT GAA GAG GAG GAG AGT GAG GAC CAA ATT CAA ATG GTA CCA
2860


Cys Glu Thr Glu Glu Glu Glu Ser Glu Asp Gln Ile Gln Met Val Pro



890                 895                 900                 905



ACT GAT GCC GTC CCA GAA GGA AAG AAC AAA GGC AAG ACC AAA AAG GGA
2908


Ser Asp Ala Val Pro Glu Gly Lys Asn Lys Gly Lys Thr Lys Lys Gly



                    910             915                 920



CGT GGT CGC AAA AAT AAC TAT AAT GCA TTC TCT CGC CGT GGT CTG AGT
2956


Arg Gly Arg Lys Asn Asn Tyr Asn Ala Phe Ser Arg Arg Gly Leu Ser



            925                 930                 935



GAT GAA GAA TAT GAA GAG TAC AAA AAG ATC AGA GAA GAA AAG AAT GGC
3004


Asp Glu Glu Tyr Glu Glu Tyr Lys Lys Ile Arg Glu Glu Lys Asn Gly



        940                 945                 950



AAT TAT AGT ATA CAA GAA TAC TTG GAG GAC CGC CAA CGA TAT GAG GAA
3052


Asn Tyr Ser Ile Gln Glu Tyr Leu Clu Asp Arg Gln Arg Tyr Glu Glu



    955                 960                 965



GAA TTA GCA GAG GTA CAG GCA GGT GGT GAT GGT GGC ATA GGA GAA ACT
3100


Glu Leu Ala Glu Val Gln Ala Gly Gly Asp Gly Gly Ile Gly Glu Thr



970                 975                 980                 985



GAA ATG GAA ATC CGT CAC AGG GTC TTC TAT AAA TCC AAG AGT AAG AAA
3148


Glu Met Glu Ile Arg His Arg Val Phe Tyr Lys Ser Lys Ser Lys Lys



                990                 995                 1000



CAC CAA CAA GAG CAA CGG CGA CAA CTT GGT CTA GTG ACT GGA TCA GAC
3196


His Gln Gln Glu Gln Arg Arg Gln Leu Gly Leu Val Thr Gly Ser Asp



            1005                1010                1015



ATC AGA AAA CGT AAG CCC ATT GAC TGG ACC CCG CCA AAG AAT GAA TGG
3244


Ile Arg Lys Arg Lys Pro Ile Asp Trp Thr Pro Pro Lys Asn Glu Trp



        1020                1025                1030



GCA GAT GAT GAC AGA GAG GTG GAT TAT AAT GAA AAG ATC AAT TTT GAA
3292


Ala Asp Asp Asp Arg Glu Val Asp Tyr Asn Glu Lys Ile Asn Phe Glu



1035                1040                1045



GCT CCC CCG ACA CTA TGG AGC CGA GTC ACA AAG TTT GGA TCA GGA TGG
3340


Ala Pro Pro Thr Leu Trp Ser Arg Val Thr Lys Phe Gly Ser Gly Trp



1050                1055                1060                1065



GGC TTT TGG GTC AGC CCG ACA GTG TTC ATC ACA ACC ACA CAT GTA GTG
3388


Gly Phe Trp Val Ser Pro Thr Val Phe Ile Thr Thr Thr His Val Val



                1070                1075                1080



CCA ACT GGT GTG AAA GAA TTC TTT GGT GAG CCC CTA TCT AGT ATA GCA
3436


Pro Thr Gly Val Lys Glu Phe Phe Gly Glu Pro Leu Ser Ser Ile Ala



            1085                1090                1095



ATC CAC CAA GCA GGT GAG TTC ACA CAA TTC AGG TTC TCA AAG AAA ATG
3484


Ile His Gln Ala Gly Glu Phe Thr Gln Phe Arg Phe Ser Lys Lys Met



        1100                1105                1110



CGC CCT GAC TTG ACA GGT ATG GTC CTT GAA GAA GGT TGC CCT GAA GGG
3532


Arg Pro Asp Leu Thr Gly Met Val Leu Glu Glu Gly Cys Pro Glu Gly



    1115                1120                1125



ACA GTC TGC TCA GTC CTA ATT AAA CGG GAT TCG GGT GAA CTA CTT CCG
3580


Thr Val Cys Ser Val Leu Ile Lys Arg Asp Ser Gly Glu Leu Leu Pro



1130                1135                1140                1145



CTA GCC GTC CGT ATG GGG GCT ATT GCC TCC ATG AGG ATA CAG GGT CGG
3628


Leu Ala Val Arg Met Gly Ala Ile Ala Ser Met Arg Ile Gln Gly Arg



                1150                1155                1160



CTT GTC CAT GGC CAA TCA GGG ATG TTA CTG ACA GGG GCC AAT GCA AAG
3676


Leu Val His Gly Gln Ser Gly Met Leu Leu Thr Gly Ala Asn Ala Lys



            1165                1170                1175



GGG ATG GAT CTT GGC ACT ATA CCA GGA GAC TGC GGG GCA CCA TAC GTC
3724


Gly Met Asp Leu Gly Thr Ile Pro Gly Asp Cys Gly Ala Pro Tyr Val



        1180                1185                1190



CAC AAG CGC GGG AAT GAG TGG GTT GTG TGT GGA GTC CAC GCT GCA GCC
3772


His Lys Arg Gly Asn Asp Trp Val Val Cys Gly Val His Ala Ala Ala



    1195                1200                1205



ACA AAG TCA GGC AAC ACC GTG GTC TGC GCT GTA CAG GCT GGA GAG GGC
3820


Thr Lys Ser Gly Asn Thr Val Val Cys Ala Val Gln Ala Gly Glu Gly



1210                1215                1220                1225



GAA ACC GCA CTA GAA GGT GGA GAC AAG GGG CAT TAT GCC GGC CAC GAG
3868


Glu Thr Ala Leu Glu Gly Gly Asp Lys Gly His Tyr Ala Gly His Glu



                1230                1235                1240



ATT GTG AGG TAT GGA AGT GGC CCA GCA CTG TCA ACT AAA ACA AAA TTC
3916


Ile Val Arg Tyr Gly Ser Gly Pro Ala Leu Ser Thr Lys Thr Lys Phe



            1245                1250                1255



TGG AGG TCC TCC CCA GAA CCA CTG CCC CCC GGA GTA TAT GAG CCA GCA
3964


Trp Arg Ser Ser Pro Glu Pro Leu Pro Pro Gly Val Tyr Glu Pro Ala



1260                        1265                1270



TAC CTG GGG GGC AAG GAC CCC CGT GTA CAG AAT GGC CCA TCC CTA CAA
4012


Tyr Leu Gly Gly Lys Asp Pro Arg Val Gln Asn Gly Pro Ser Leu Gln



    1275                1280                1285



CAG GTA CTA CGT GAC CAA CTG AAA CCC TTT GCG GAG CCC CGC GGC CGC
4060


Gln Val Leu Arg Asp Gln Leu Lys Pro Phe Ala Asp Pro Arg Gly Arg



1290                1295                1300                1305



ATG CCT GAG CCT GGC CTA CTG GAG GCT GCG GTT GAG ACT GTA ACA TCC
4108


Met Pro Glu Pro Gly Leu Leu Glu Ala Ala Val Glu Thr Val Thr Ser



                1310                1315                1320



ATG TTA GAA CAG ACA ATG GAT ACC CCA AGC CCG TGG TCT TAC GCT GAT
4156


Met Leu Glu Gln Thr Met Asp Thr Pro Ser Pro Trp Ser Tyr Ala Asp



            1325                1330                1335



GCC TGC CAA TCT CTT GAC AAA ACT ACT AGT TCG GGG TAC CCT CAC CAT
4204


Ala Cys Gln Ser Leu Asp Lys Thr Thr Ser Ser Gly Tyr Pro His His



        1340                1345                1350



AAA AGG AAG AAT GAT GAT TGG AAT GGC ACC ACC TTC GTT GGA GAG CTC
4252


Lys Arg Lys Asn Asp Asp Trp Asn Gly Thr Thr Phe Val Gly Glu Leu



    1355                1360                1365



GGT GAG CAA GCT GCA CAC GCC AAC AAT ATG TAT GAG AAT GCT AAA CAT
4300


Gly Glu Gln Ala Ala His Ala Asn Asn Met Tyr Glu Asn Ala Lys His



1370                1375                1380                1385



ATG AAA CCC ATT TAC ACT GCA GCC TTA AAA GAT GAA CTA GTC AAG CCA
4348


Met Lys Pro Ile Tyr Thr Ala Ala Leu Lys Asp Glu Leu Val Lys Pro



                1390                1395                1400



GAA AAG ATT TAT CAA AAA GTC AAG AAG CGT CTA CTA TGG GGC GCC GAT
4396


Glu Lys Ile Tyr Gln Lys Val Lys Lys Arg Leu Leu Trp Gly Ala Asp



            1405                1410                1415



CTC GGA ACA GTG GTC AGG GCC GCC CGG GCT TTT GGC CCA TTT TGT GAC
4444


Leu Gly Thr Val Val Arg Ala Ala Arg Ala Phe Gly Pro Phe Cys Asp



        1420                1425                1430



GCT ATA AAA TCA CAT GTC ATC AAA TTG CCA ATA AAA GTT GGC ATG AAC
4492


Ala Ile Lys Ser His Val Ile Lys Leu Pro Ile Lys Val Gly Met Asn



    1435                1440                1445



ACA ATA GAA GAT GGC CCC CTC ATC TAT GCT GAG CAT GCT AAA TAT AAG
4540


Thr Ile Glu Asp Gly Pro Leu Ile Tyr Ala Glu His Ala Lys Tyr Lys



1450                1455                1460                1465



AAT CAT TTT GAT GCA GAT TAT ACA GCA TGG GAC TCA ACA CAA AAT AGA
4588


Asn His Phe Asp Ala Asp Tyr Thr Ala Trp Asp Ser Thr Gln Asn Arg



                1470                1475                1480



CAA ATT ATG ACA GAA TCC TTC TCC ATT ATG TCG CGC CTT ACG GCC TCA
4636


Gln Ile Met Thr Glu Ser Phe Ser Ile Met Ser Arg Leu Thr Ala Ser



            1485                1490                1495



CCA GAA TTG GCC GAG GTT GTG GCC CAA GAT TTG CTA GCA CCA TCT GAG
4684


Pro Glu Leu Ala Glu Val Val Ala Gln Asp Leu Leu Ala Pro Ser Glu



        1500                1505                1510



ATG GAT GTA GGT GAT TAT GTC ATC AGG GTC AAA GAG GGG CTG CCA TCT
4732


Met Asp Val Gly Asp Tyr Val Ile Arg Val Lys Glu Gly Leu Pro Ser



    1515                1520                1525



GGA TTC CCA TGT ACT TCC CAG GTG AAC AGC ATA AAT CAC TGG ATA ATT
4780


Gly Phe Pro Cys Thr Ser Gln Val Asn Ser Ile Asn His Trp Ile Ile



1530                1535                1540                1545



ACT CTC TGT GCA CTG TCT GAG GCC ACT GGT TTA TCA CCT GAT GTG GTG
4828


Thr Leu Cys Ala Leu Ser Glu Ala Thr Gly Leu Ser Pro Asp Val Val



                1550                1555                1560



CAA TCC ATG TCA TAT TTC TCA TTT TAT GGT GAT GAT GAG ATT GTG TCA
4876


Gln Ser Met Ser Tyr Phe Ser Phe Tyr Gly Asp Asp Glu Ile Val Ser



            1565                1570                1575



ACT GAC ATA GAT TTT GAC CCA GCC CGC CTC ACT CAA ATT CTC AAG GAA
4924


Thr Asp Ile Asp Phe Asp Pro Ala Arg Leu Thr Gln Ile Leu Lys Glu



        1580                1585                1590



TAT GGC CTC AAA CCA ACA AGG CCT GAC AAA ACA GAA GGA CCA ATA CAA
4972


Tyr Gly Leu Lys Pro Thr Arg Pro Asp Lys Thr Glu Gly Pro Ile Gln



    1595                1600                1605



GTG AGG AAA AAT GTG GAT GGA CTG GTC TTC TTG CGG CGC ACC ATT TCC
5020


Val Arg Lys Asn Val Asp Gly Leu Val Phe Leu Arg Arg Thr Ile Ser



1610                1615                1620                1625



CGT GAT GCG GCA GGG TTC CAA GGC AGG TTA GAT AGG GCT TCG ATT GAA
5068


Arg Asp Ala Ala Gly Phe Gln Gly Arg Leu Asp Arg Ala Ser Ile Glu



                1630                1635                1640



CGC CAA ATC TTC TGG ACC CGC GGG CCC AAT CAT TCA GAT CCA TCA GAG
5116


Arg Gln Ile Phe Trp Thr Arg Gly Pro Asn His Ser Asp Pro Ser Glu



            1645                1650                1655



ACT CTA GTG CCA CAC ACT CAA AGA AAA ATA CAG TTG ATT TCA CTT CTA
5164


Thr Leu Val Pro His Thr Gln Arg Lys Ile Gln Leu Ile Ser Leu Leu



        1660                1665                1670



GGG GAA GCT TCA CTC CAT GGT GAG AAA TTT TAC AGA AAG ATT TCC AGC
5212


Gly Glu Ala Ser Leu His Gly Glu Lys Phe Tyr Arg Lys Ile Ser Ser



    1675                1680                1685



AAG GTC ATA CAT GAA ATC AAG ACT GGT GGA TTG GAA ATG TAT GTC CCA
5260


Lys Val Ile His Glu Ile Lys Thr Gly Gly Leu Glu Met Tyr Val Pro



1690                1695                1700                1705



GGA TGG CAG GCC ATG TTC CGG TGG ATG CGC TTC CAT GAC CTC GGA TTG
5308


Gly Trp Gln Ala Met Phe Arg Trp Met Arg Phe His Asp Leu Gly Leu



                1710                1715                1720



TGG ACA GGA GAT CGG GAT CTT CTG CCC GAA TTC GTA AAT GAT GAT GGC
5356


Trp Thr Gly Asp Arg Asp Leu Leu Pro Glu Phe Val Asn Asp Asp Gly



            1725                1730                1735



GTC TAAGGACGCT ACATCAAGCG TGGATGGCGC TAGTGGCGCT GGTCAGTTGG
5409


Val

















TABLE 3





The amino acid sequence deduced from nucleotides 5346 through



6935 of the Norwalk virus genome shown in Table 1.

















CGTAA ATG ATG ATG GCG TCT AAG GAC GCT ACA TCA AGC GTG GAT GGC
5387



      Met Met Met Ala Ser Lys Asp Ala Thr Ser Ser Val Asp Gly


        1               5                  10



GCT AGT GGC GCT GGT CAG TTG GTA CCG GAG GTT AAT GCT TCT GAC CCT
5435


Ala Ser Gly Ala Gly Gln Leu Val Pro Glu Val Asn Ala Ser Asp Pro


 15                  20                  25                  30



CTT GCA ATG GAT CCT GTA GCA GGT TCT TCG ACA GCA GTC GCG ACT GCT
5483


Leu Ala Met Asp Pro Val Ala Gly Ser Ser Thr Ala Val Ala Thr Ala


                 35                  40                  45



GGA CAA GTT AAT CCT ATT GAT CCC TGG ATA ATT AAT AAT TTT GTG CAA
5531


Gly Gln Val Asn Pro Ile Asp Pro Trp Ile Ile Asn Asn Phe Val Gln


             50                  55                  60



GCC CCC CAA GGT GAA TTT ACT ATT TCC CCA AAT AAT ACC CCC GGT GAT
5579


Ala Pro Gln Gly Glu Phe Thr Ile Ser Pro Asn Asn Thr Pro Gly Asp


         65                  70                  75



GTT TTG TTT GAT TTG AGT TTG GGT CCC CAT CTT AAT CCT TTC TTG CTC
5627


Val Leu Phe Asp Leu Ser Leu Gly Pro His Leu Asn Pro Phe Leu Leu


     80                  85                  90



CAT CTA TCA CAA ATG TAT AAT GGT TGG GTT GGT AAC ATG AGA GTC AGG
5675


His Leu Ser Gln Met Tyr Asn Gly Trp Val Gly Asn Met Arg Val Arg


 95                 100                 105                 110



ATT ATG CTA GCT GGT AAT CCC TTT ACT GCG GGG AAG ATA ATA GTT TCC
5723


Ile Met Leu Ala Gly Asn Ala Phe Thr Ala Gly Lys Ile Ile Val Ser


                115                 120                 125



TGC ATA CCC CCT GGT TTT GGT TCA CAT AAT CTT ACT ATA GCA CAA GCA
5771


Cys Ile Pro Pro Gly Phe Gly Ser His Asn Leu Thr Ile Ala Gln Ala


            130                 135                 140



ACT CTC TTT CCA CAT GTG ATT GCT GAT GTT AGG ACT CTA GAC CCC ATT
5819


Thr Leu Phe Pro His Val Ile Ala Asp Val Arg Thr Leu Asp Pro Ile


        145                 150                 155



GAG GTG CCT TTG GAA GAT GTT AGG AAT GTT CTC TTT CAT AAT AAT GAT
5867


Glu Val Pro Leu Glu Asp Val Arg Asn Val Leu Phe His Asn Asn Asp


    160                 165                 170



AGA AAT CAA CAA ACC ATG CGC CTT GTG TGC ATG CTG TAC ACC CCC CTC
5915


Arg Asn Gln Gln Thr Met Arg Leu Val Cys Met Leu Tyr Thr Pro Leu


175                 180                 185                 190



CGC ACT GGT GGT GGT ACT GGT GAT TGT TTT GTA GTT GCA GGG CGA GTT
5963


Arg Thr Gly Gly Gly Thr Gly Asp Ser Phe Val Val Ala Gly Arg Val


                195                 200                 205



ATG ACT TGC CCC AGT CCT GAT TTT AAT TTC TTG TTT TTA GTC CGT CCT
6011


Met Thr Cys Pro Ser Pro Asp Phe Asn Phe Leu Phe Leu Val Pro Pro


            210                 215                 220



ACG GTG GAG CAG AAA ACC AGG CCC TTC ACA CTC CCA AAT CTG CCA TTG
6059


Thr Val Glu Gln Lys Thr Arg Pro Phe Thr Leu Pro Asn Leu Pro Leu


        225                 230                 235



AGT TCT CTG TCT AAC TCA CGT GCC CCT CTC CCA ATC AGT AGT ATG GGC
6107


Ser Ser Leu Ser Asn Ser Arg Ala Pro Leu Pro Ile Ser Ser Met Gly


    240                 245                 250



ATT TCC CCA GAC AAT GTC CAG AGT GTG CAG TTC CAA AAT GGT CGG TGT
6155


Ile Ser Pro Asp Asn Val Gln Ser Val Gln Phe Gln Asn Gly Arg Cys


255                 260                 265                 270



ACT CTG GAT GGC CGC CTG GTT GGC ACC ACC CCA GTT TCA TTG TCA CAT
6203


Thr Leu Asp Gly Arg Leu Val Gly Thr Thr Pro Val Ser Leu Ser His


                275                 280                 285



GTT GCC AAG ATA AGA GGG ACC TCC AAT GGC ACT GTA ATC AAC CTT ACT
6251


Val Ala Lys Ile Arg Gly Thr Ser Asn Gly Thr Val Ile Asn Leu Thr


            290                 295                 300



GAA TTG GAT GGC ACA CCC TTT CAC CCT TTT GAG GGC CCT GCC CCC ATT
6299


Glu Leu Asp Gly Thr Pro Phe His Pro Phe Glu Gly Pro Ala Pro Ile


        305                 310                 315



GGG TTT CCA GAC CTC GGT GGT TGT GAT TGG CAT ATC AAT ATG ACA CAG
6347


Gly Phe Pro Asp Leu Gly Gly Cys Asp Trp His Ile Asn Met Thr Gln


    320                 325                 330



TTT GGC CAT TCT AGC CAG ACC CAG TAT GAT GTA GAC ACC ACC CCT GAC
6395


Phe Gly His Ser Ser Gln Thr Gln Tyr Asp Val Asp Thr Thr Pro Asp


335                 340                 345                 350



ACT TTT GTC CCC CAT CTT GGT TCA ATT CAG GCA AAT GGC ATT GGC AGT
6443


Thr Phe Val Pro His Leu Gly Ser Ile Gln Ala Asn Gly Ile Gly Ser


                355                 360                 365



GGT AAT TAT GTT GGT GTT GTT AGC TGG ATT TCC CCC CCA TCA CAC CCG
6491


Gly Asn Tyr Val Gly Val Leu Ser Trp Ile Ser Pro Pro Ser His Pro


            370                 375                 380



TCT GGC TCC CAA GTT GAC CTT TGG AAG ATC CCC AAT TAT GGG TCA AGT
6539


Ser Gly Ser Gln Val Asp Leu Trp Lys Ile Pro Asn Tyr Gly Ser Ser


        385                 390                 395



ATT ACG GAG GCA ACA CAT CTA GCC CCT TCT GTA TAC CCC CGT GGT TTC
6587


Ile Thr Glu Ala Thr His Leu Ala Pro Ser Val Tyr Pro Pro Gly Phe


    400                 405                 410



GGA GAG GTA TTG GTC TTT TTC ATG TCA AAA ATG CCA GGT CCT GGT GCT
6635


Gly Glu Val Leu Val Phe Phe Met Ser Lys Met Pro Gly Pro Gly Ala


415                 420                 425                 430



TAT AAT TTG CCC TGT CTA TTA CCA CAA GAG TAC ATT TCA CAT CTT GCT
6683


Tyr Asn Leu Pro Cys Leu Leu Pro Gln Glu Tyr Ile Ser His Leu Ala


                435                 440                 445



AGT GAA CAA GCC CCT ACT GTA GGT GAG GCT GCC CTG CTC CAC TAT GTT
6731


Ser Glu Gln Ala Pro Thr Val Gly Glu Ala Ala Leu Leu His Tyr Val


            450                 455                 460



GAC CCT GAT ACC GGT CGG AAT CTT GGG GAA TTC AAA GCA TAC CCT GAT
6779


Asp Pro Asp Thr Gly Arg Asn Leu Gly Glu Phe Lys Ala Tyr Pro Asp


        465                 470                 475



GGT TTC CTC ACT TGT GTC CCC AAT GGG GCT AGC TCG GGT CCA CAA CAG
6827


Gly Phe Leu Thr Cys Val Pro Asn Gly Ala Ser Ser Gly Pro Gln Gln


    480                 485                 490



CTG CCG ATC AAT GGG GTC TTT GTC TTT GTT TCA TGG GTG TCC AGA TTT
6875


Leu Pro Ile Asn Gly Val Phe Val Phe Val Ser Trp Val Ser Arg Phe


495                 500                 505                 510



TAT CAA TTA AAG CCT GTG GGA ACT GCC AGC TCG GCA AGA GGT AGG CTT
6923


Tyr Gln Leu Lys Pro Val Gly Thr Ala Ser Ser Ala Arg Gly Arg Leu


                515                 520                 525



GGT CTG CGC CGA TAATGGCCCA AGCCATAATT GGTGCAATTG CTGCTTCCAC
6975


Gly Leu Arg Arg


            530

















TABLE 4





The amino acid sequence deduced from nucleotides 6938 through



7573 of the Norwalk virus genome shown in Table 1.

















CCAGCTCGGC AAGAGGTAGG CTTGGTCTGC GCCGATA ATG GCC CAA GCC ATA ATT
6955



                                         Met Ala Gln Ala Ile Ile


                                           1               5


GGT GCA ATT GCT GCT TCC ACA GCA GGT AGT GCT CTG GGA GCG GGC ATA
7003


Gly Ala Ile Ala Ala Ser Thr Ala Gly Ser Ala Leu Gly Ala Gly Ile



             10                  15                  20


CAG GTT GGT GGC GAA GCG GCC CTC CAA AGC CAA AGG TAT CAA CAA AAT
7051


Gln Val Gly Gly Glu Ala Ala Leu Gln Ser Gln Arg Tyr Gln Gln Asn


         25                  30                  35


TTG CAA CTG CAA GAA AAT TCT TTT AAA CAT GAC AGG GAA ATG ATT GGG
7099


Leu Gln Leu Gln Glu Asn Ser Phe Lys His Asp Arg Glu Met Ile Gly


     40                  45                  50


TAT CAG GTT GAA GCT TCA AAT CAA TTA TTG GCT AAA AAT TTG GCA ACT
7147


Tyr Gln Val Glu Ala Ser Asn Gln Leu Leu Ala Lys Asn Leu Ala Thr


55                   60                  65                  70


AGA TAT TCA CTC CTC CGT GCT GGG GGT TTG ACC AGT GCT CAT GCA GCA
7195


Arg Tyr Ser Leu Leu Arg Ala Gly Gly Leu Thr Ser Ala Asp Ala Ala


                 75                  80                  85


AGA TCT GTG GCA GGA GCT CCA GTC ACC CGC ATT GTA GAT TGG AAT GGC
7243


Arg Ser Val Ala Gly Ala Pro Val Thr Arg Ile Val Asp Trp Asn Gly


             90                  95                 100


GTG AGA GTG TCT GCT CCC GAG TCC TCT GCT ACC ACA TTG AGA TCC GGT
7291


Val Arg Val Ser Ala Pro Glu Ser Ser Ala Thr Thr Leu Arg Ser Gly


        105                 110                 115


GGC TTC ATG TCA GTT CCC ATA CCA TTT GCC TCT AAG CAA AAA CAG GTT
7339


Gly Phe Met Ser Val Pro Ile Pro Phe Ala Ser Lys Gln Lys Gln Val


    120                 125                 130


CAA TCA TCT GGT ATT ACT AAT CCA AAT TAT TCC CCT TCA TCC ATT TCT
7387


Gln Ser Ser Gly Ile Ser Asn Pro Asn Tyr Ser Pro Ser Ser Ile Ser


135                 140                 145                 150


CGA ACC ACT AGT TGG GTC GAG TCA CAA AAC TCA TCG AGA TTT GGA AAT
7435


Arg Thr Thr Ser Trp Val Glu Ser Gln Asn Ser Ser Arg Phe Gly Asn


                155                 160                 165


CTT TCT CCA TAC CAC GCG GAG GCT CTC AAT ACA GTG TGG TTG ACT CCA
7483


Leu Ser Pro Tyr His Ala Glu Ala Leu Asn Thr Val Trp Leu Thr Pro


            170                 175                 180


CCC GGT TCA ACA GCC TCT TCT ACA CTG TCT TCT GTG CCA CGT GGT TAT
7531


Pro Gly Ser Thr Ala Ser Ser Thr Leu Ser Ser Val Pro Arg Gly Tyr


        185                 190                 195


TTC AAT ACA GAC AGG TTG CCA TTA TTC GCA AAT AAT AGG CGA
7573


Phe Asn Thr Asp Arg Leu Pro Leu Phe Ala Asn Asn Arg Arg


    200                 205                 210

## Claims

1. A method of inducing an immune response against Norwalk virus in an animal comprising the step of administering to the animal an effective amount of a composition having a purified Norwalk virus immunogen that forms a stable virus-like particle lacking nucleic acids, wherein the immunogen is produced in an expression system using the nucleotide sequence of SEQ. ID. NO.1.

2. The method of claim 1, wherein the immunogen is produced in an expression system using nucleotides 5337 through 7724 of SEQ. ID. NO.1.

3. The method of claim 1, wherein the composition is administered orally.

4. The method of claim 1, wherein the composition is administered parenterally.

5. The method of claim 1, wherein the virus-like particle is non-infectious.

6. The method of claim 3, wherein the composition is administered subsequent to oral administration of sodium bicarbonate.

7. The method of claim 3, wherein the composition is administered prior to oral administration of sodium bicarbonate.

8. The method of claim 3, wherein sodium bicarbonate is administered orally following administration of the composition.