bluuebunny/crossref_metadata_2025 huggingface dataset:
Transfection of Streptococcus sanguis by phage deoxyribonucleic acid isolated from Streptococcus mutans
Authors: Higuchi M , Rhee G H , Araya S , Higuchi M
Published: January 2020

Streptococcus sanguis ATCC 10556 cells were infected with free phage DNA of S, mutans strain PK 1. Two transformants were isolated which made colonies with large mucoid forms on mitis-salivarius agar. Both transformants had an increased ability to synthesize insoluble glucan and showed an adhesive nature on glass surfaces. These characteristics of the transformants bear a resemblance to S. mutans. These transformants had many physiological characteristics by which they could be recognized as S. sanguis. However, they resembled S. salivarius in forming a large amount of soluble fructan. Furthermore, the transformant cells did not produce ammonia from arginine, whereas their parent cells did.
Oral toxicities of Clostridium botulinum toxins in response to molecular size
Authors: Ohishi I , Sugii S , Sakaguchi G
Published: January 2020

Clostridium botulinum type A, B, and F toxins of different molecular sizes were fed to mice to compare the oral toxicities. The progenitor toxin, a complex of a toxic and nontoxic component, of any type was higher in oral toxicity to mice than the dissociated toxic component or the derivative toxin. The former may no doubt play a more important role in the pathogenesis of food-borne botulism. The higher oral toxicity possessed by the progenitor toxin, including the exceptionally high one found with type B-L toxin, can be explained solely by the protection afforded by the nontoxic component attached to the toxic component. The possibility of the highest oral toxicity of type B-L toxin to humans is discussed.
Selectivity of the 2-deoxyglucose transport system in human and guinea pig polymorphonuclear leukocytes
Authors: Litchfield W J , Wells W W
Published: January 2020

To determine whether the deleterious action of D-galactose upon phagocyte function could be related to inhibition of glucose uptake, the properties of glucose transport were investigated by following the incorporation of [G-3H]2-deoxyglucose into human and guinea pig polymorphonuclear leukocytes (PMN). Uptake of [G-3H]2-deoxyglucose by guinea pig PMN proceeded in vitro with a Km of 1.8 mM and Vmax of 0.67 nmol/min per 10(6) cells. This system was competitively inhibited by glucose and mannose but was not significantly affected by galactose, fructose, or 3-0-methylglucose. Maximal uptake of 2-deoxyglucose occurred at 41 degrees C, and phosphorylation was necessary for its intracellular concentration. Transport of 2-deoxyglucose, although not altered by uncouplers of oxidative phosphorylation, was sensitive to inhibitors of glycolysis. Preincubation of cells with 2 mM iodoacetate for 30 min significantly reduced the uptake of 2-deoxyglucose and the intracellular levels of adenosine-5'-triphosphate without decreasing cell viability. These results indicated that uptake of 2-deoxyglucose in guinea pig PMN occurred by facilitated diffusion with subsequent phosphorylation. Similar results were obtained with PMN isolated from human peripheral blood.
Structure-activity relationships of an exotoxin of Pseudomonas aeruginosa
Authors: Vasil M L , Kabat D , Iglewski B H
Published: January 2020

The relation of the structure of Pseudomonas aeruginosa exotoxin A (PA toxin) to its enzymatic activity (adenosine 5'-diphosphate-ribosyl transferase) in vitro and to its toxicity in vivo was examined. PA toxin is produced as a single polypeptide chain with a molecular weight of about 71,500. PA toxin is produced by Pseudomonas as a toxic proenzyme that lacks enzymatic activity. Adenosine 5'-diphosphate-ribosyl transferase activity is expressed when the molecule is denatured and reduced or when its is cleaved by Pseudomonas proteases to yield an enzymatically active 27,000-dalton fragment (fragment a). A 45,000-dalton protein is tentatively identified as the enzymatically inactive fragment b of PA toxin. Enzymatically active forms of the toxin lack toxicity for mouse L-cells or mouse lethality. Thus, it is concluded that the native toxin proenzyme is required for toxicity and that a structural rearrangement must precede its intracellular activity.
Effect of zinc on peritoneal macrophages in vitro
Authors: Chvapil M , Stankova L , Bernhard D S , Weldy P L , Carlson E C , Campbell J B
Published: January 2020

Rat peritoneal macrophages incubated in a medium with 10% autologous serum showed 50% inhibition of O2 consumption by 0.4 mM zinc only when activated by yeast. Zinc ions had no effect on resting macrophages. The inhibitory efficiency of zinc depended on the ratio of yeast particles to macrophages; with more activated cells, the inhibition was less. The multiple-shaped intact macrophages changed into rounded cells in the presence of 0.1 and 0.5 mM Zn2+ as shown by photomicrography and scanning electron microscopy. When the incubation medium was replaced by zinc-free medium, cells recovered and became irregularly shaped. The reversibility of zinc effect on cell morphology corresponded with uptake and release of zinc by macrophages. The presence of serum in the medium interfered with the magnitude of zinc uptake by macrophages. We conclude that besides already reported effects of zinc on mast cells, platelets, and granulocytes, zinc ions also inhibit some functions of macrophages.
Antigenic relationships among thiol-activated cytolysins
Authors: Cowell J L , Bernheimer A W
Published: January 2020

Cereolysin, streptolysin O, and perfringolysin O formed precipitin lines that completely fused when reacted with horse antitetanolysin by Ouchterlony immunodiffusion and formed precipitin lines that showed either partial or complete fusion when diffused against horse antistreptolysin O or antiperfringolysin O.
Use of a free viral immunofluorescence assay to detect human reovirus-like agent in human stools
Authors: Yolken R H , Wyatt R G , Kalica A R , Kim H W , Brandt C D , Parrott R H , Kapikian A Z , Chanock R M
Published: January 2020

Human reovirus-like agent (HRVLA) is a major cause of gastroenteritis in infants and young children in many parts of the world. Detection of HRVLA in stools is impractical with the techniques currently available. We describe a rapid immunofluorescence assay for detection of HRVLA in stools. Results with this assay agreed well with results obtained from examination of stool specimens by electron microscopy.
Biochemical and immunological characterization of deoxythymidine kinase of thymidine kinaseless HeLa cells biochemically transformed by herpes simplex virus type
Authors: Cheng Y C , Chadha K C , Hughes R G
Published: January 2020

Thymidine kinase (TK) from herpes simplex virus type 1 (HSV-1) biochemically transformed HeLa cells, purified by affinity chromatography, has been characterized with respect to its electrophoretic mobility, molecular weight, activation energy, substrate specificity, and immunological specificity. TK purified from HSV-1-transformed HeLa cells has the same electrophoretic mobility as TK purified from HeLa cells lytically infected with HSV-1. The sedimentation velocity of purified TK from transformed cells was similar to that previously reported for the lytic enzyme, and its molecular weight was estimated to be 70,000. The activation energy of purified transformed-cell TK was 18.3 kcal/mol. Antiserum prepared against purified HSV-1 TK, although it showed some cross-reactivity, preferentially neutralized homologous TK. The transformed-cell TK antiserum also neutralized the deoxycytidine kinase activity of HSV-1-infected cell extracts but had no effect on deoxycytidine kinase activity of HSV-2-infected cell extract. These results further support the notion that TK acquired by HeLa cells transformed by HSV-1 is of viral and not of cellular origin.
Inhibition of small-intestinal sugar and amino acid transport by the enterotoxin of Shigella dysenteriae I
Authors: Binder H J , Whiting D S
Published: January 2020

The enterotoxin of Shigella dysenteriae I produces fluid and electrolyte secretion in the rabbit ileum. These present studies were designed to evaluate nonelectrolyte transport in rabbit ileal mucosa exposed to Shigella enterotoxin. Both 10 mM galactose and 5 mM L-alanine absorptions were significantly impaired in enterotoxin-exposed ileal mucosa compared with control mucosa. L-Alanine influx was not imparied in two other secretory processes: that induced by cholera enterotoxin and hyperosmolarity. These studies provide evidence that both surgar and amino acid absorptions are diminished in the small intestine by the enterotoxin of S. dysenteriae I.
Chicken Embryo as an Animal Model for Gonorrhea
Authors: Foster R. Scott , Vinson J. William
Published: January 2020

Parameters of infection of the chicken embryo with
Neisseria gonorrhoeae
were defined in order to standardize infectious and lethal doses. Virulent (T1) and avirulent (T3) gonococci from two strains were used to infect 7- to 12-day-old White Leghorn chicken embryos via the yolk sac (YS) or chorioallantoic membrane (CAM) route. Infection of embryos was established following YS inoculation of 1 to 10 viable gonococci. Although 8- to 10-day-old embryos were the most susceptible, an inoculum of less than 100 gonococci was sufficient to kill any age embryo via this route. Embryos were less susceptible to infection via the CAM, where an inoculum of from 10
5
to 10
6
colony-forming units was lethal by 42 h. Strain and morphological type had a variable influence on the ability of the gonococcus to infect and kill the chicken embryo by either route; however, agar-grown and broth-grown organisms produced consistently similar mean lethal dose (LD
50
) and mean infective dose (ID
50
) values. LD
50
and ID
50
differences between T1 and T3 gonococci from strain 72H641 were not apparent after either YS or CAM inoculation of 8- or 10-day chicken embryos, respectively. YS and CAM LD
50
values for strain 72H641 T1 and T3 and CDC 9 T3 were also similar; however, these values were slightly lower for CDC 9 T1. In terms of infectivity or colonization, CDC 9 T1 and T3 had higher ID
50
values via the YS and lower ID
50
values via the CAM than 72H641. CDC 9 T1 was slightly more infective via the YS and less infective via the CAM than its T3 counterpart. Although the gonococcal strain used will influence interpretation of results, infection of both YS and CAM was highly reproducible in terms of gross pathology and of LD
50
and ID
50
data for a particular strain and colony type.
Properties of a Variant of
Streptococcus mutans
Altered in Its Ability to Interact with Glucans
Authors: Janda William M. , Kuramitsu Howard K.
Published: January 2020

After continuous subculture of
Streptococcus mutans
GS-5, the resultant organism, GS-5var, was found to be altered in its ability to undergo dextran- and sucrose-induced cell agglutination and to adhere to smooth surfaces in the presence of sucrose. Both GS-5 and GS-5var cells possessed the serotype
c
polysaccharide antigen, displayed similar growth kinetics, appeared to have similar metabolic and biosynthetic capabilities, and produced similar amounts of cell-associated and extracellular glucosyltransferase activity in chemically defined medium. GS-5 cells which had bound exogenous glucosyltransferase enzymes from either cell type were able to undergo sucrose-dependent adherence to smooth surfaces, whereas GS-5var cells which had bound comparable levels of glucosyltransferase activity were unable to adhere. In contrast to GS-5var cells, GS-5 cells were also able to adhere to preformed glucan deposits. In addition, [
14
C]glucan binding studies demonstrated that GS-5 cells were able to bind fourfold-greater levels of [
14
C]glucan relative to GS-5var cells having similar cell-associated glucosyltransferase activity. Further study of GS-5 cells also suggested the existence of a glucan binding site, distinct from the cell-associated glucosyltransferase activity, which is important in dextran-induced agglutination and sucrose-dependent adherence to smooth surfaces. These results are discussed in terms of the alteration of the GS-5var cells and their possible relationship to the putative receptors for glucosyltransferase enzymes and glucans on the cell surface of
S. mutans.
Bacterial Interference IV. Epidemiological Determinants of the Antagonistic Activity of the Normal Throat Flora Against Group A Streptococci
Authors: Sanders Christine C. , Nelson Gerald E. , Sanders W. Eugene
Published: January 2020

A study was performed to identify epidemiological factors such as age, race, sex, and time of culture that might influence the ability of the normal pharyngeal flora to interfere with growth of group A streptococci. From March 1974 through February 1975, throat swabs were obtained from 952 individuals. Cultures were assayed by an agar overlay procedure for the presence of bacteria capable of inhibiting growth of group A streptococci. The observed inhibition was then determined to be bacteriostatic or bactericidal by use of a broth filtrate technique. Regardless of age, race, or sex, subjects were more likely to harbor interfering flora if cultured during the months of March and April, which coincided with the highest prevalence of group A streptococci in the community. Race and sex of subjects appeared not to influence the inhibitory activity of throat flora either quantitatively or qualitatively. However, among individuals with interfering flora, the prevalence of bactericidal organisms increased and bacteriostatic organisms decreased with advancing age. Since the presence of bactericidal, and not bacteriostatic, organisms has been associated with resistance to colonization of the throat by group A streptococci, this higher prevalence of bactericidal organisms in older individuals suggests that bacterial interference may be one of the mechanisms that account for the greater resistance of adults than children to streptococcal throat infection.
Direct serological assay for the heat-labile enterotoxin of Escherichia coli, using passive immune hemolysis
Authors: Evans D J , Evans D G
Published: January 2020

Sheep erythrocytes sensitized with the heat-labile enterotoxin (LT) of Escherichia coli exhibited passive immune hemolysis (PIH) when exposed to specific antitoxin and complement. Thus, PIH serves as the basis for an in vitro serological assay for LT that is sufficiently specific and sensitive to differentiate LT-positive and LT-negative E. coli isolates. The PIH assay for E. coli LT has been performed with the standard Microtiter system and also by a tube method employing the spectrophotometric determination of hemoglobin release. The spectrophotometric method enhances the sensitivity, accuracy, and objectivity of the PIH assay. The increased sensitivity of the spectrophotometric method also facilitates the identification of LT-positive cultures employing polymyxin "mini-extracts" of whole overnight (18 h) broth cultures of 2.0% Casamino Acid-0.6% yeast extract-salts medium rather than mini-extracts of cells derived from 3.5-h subcultures. Thus, large numbers of E. coli isolates can be individually tested for LT in less than 24 h after broth inoculation by a rapid in vitro assay which requires anti-LT serum as the only specific reagent.
Replica-Plating Virulence Assay for
Agrobacterium tumefaciens
Authors: Matthysse A. G. , Ratliff S. , Salberg J.
Published: January 2020

Replica plating onto wounded tobacco leaves provides a convenient method for screening for avirulent mutants of
Agrobacterium tumefaciens.
Bacteriocins as Factors in the In Vitro Interaction Between Oral Streptococci in Plaque
Authors: Weerkamp A. , Bongaerts-Larik L. , Vogels G. D.
Published: January 2020

The effect of bacteriocins on the composition of dental plaque flora was studied in vitro with bacterial plaque formed by oral streptococci on glass rods suspended in broth medium. Cell-free preparations containing mutacin SW31, a bacteriocin produced by
Streptococcus mutans
, killed sensitive cells present in the plaque selectively, but did not affect resistant cells. Similar preparations from a non-bacteriocinogenic mutant exerted only a slight effect. Mixed growth of bacteriocin-producing
S. mutans
SW31 with the sensitive
S. sanguis
Ny101 resulted in a nearly single-strain plaque of the former. Mutacin could be detected in the plaque substance as well as in the surrounding medium. A non-bacteriocinogenic mutant, which was shown not to be altered in functions affecting growth in plaque, allowed substantial growth of
S. sanguis
Ny101. Sequential inoculation of the bacteriocinogenic plaque former
S. sanguis
P3A3 and the sensitive
S. mutans
OMZ61 showed that the cells of the latter are killed rapidly in established plaques when inoculated with the bacteriocinogenic strain. A trypsin-sensitive antagonistic substance could be detected in the plaque, but not in the surrounding medium. The results indicate that bacteriocins can be active in plaque in vitro and suggest that bacteriocins could play a role in determining the composition of plaque in vivo.
Effect of anti-mu-chain-specific immunosuppression on Chikungunya virus encephalitis of mice
Authors: Giovarelli M , Viano I , Zucca M , Valbonesi R , Dianzani F
Published: January 2020

Mice neonatally immunosuppressed with anti-mu antiserum failed to produce circulating antibodies to sheep erythrocytes and showed a marked decrease in circulating immunoglobulins. However, when they were intracerebrally infected with Chikungunya virus (a group A togavirus), they showed a mortality rate consistently lower than non-immunosuppressed control mice. Several possible explanations for this finding are discussed.
Cellular basis of persistent lymphocytosis in cattle infected with bovine leukemia virus
Authors: Kenyon S J , Piper C E
Published: January 2020

Peripheral blood lymphocytes from 14 cattle infected with the bovine leukemia virus (BLV) and 14 BLV-free cattle were examined by the membrane immunofluorescent antibody technique to detect surface immunoglobulin (S-Ig) and by the erythrocyte-antibody-complement (EAC) rosette test for the detection of complement receptors. Direct comparisons of the percentages of S-Ig-bearing cells and EAC rosette-forming cells in both infected and BLV-free animals showed no evidence for the presence of a substantial population bearing one surface marker but not the other. The data showed that cells with surface markers characteristic of B lymphocytes are responsible for most of the increase in peripheral blood lymphocytes which may accompany BLV infection. The release of infectious BLV and the spontaneous uptake of thymidine by short-term cultured peripheral blood lymphocytes from BLV-infected cattle were also studied. The results indicate that both of these activities are function of B lymphocytes.
Properties of density gradient-fractionated peripheral blood leukocytes from cattle infected with bovine leukemia virus
Authors: Kenyon S J , Piper C E
Published: January 2020

Discontinuous bovine serum albumin gradients were used to fractionate peripheral blood leukocytes from bovine leukemia virus (BLV)-free and BLV-infected cows. The release of infectious BLV and spontaneous incorporation of [3H]thymidine were not properties of density gradient-fractionated leukocytes from a BLV-free cow. When leukocytes from BLV-infected cattle were fractionated, B lymphocytes which spontaneously incorporated [3H]thymidine could be separated as a distinct subpopulation from B lymphocytes which replicated infectious BLV. Density gradient fractionation of leukocytes from a cow with lymphosarcoma is also reported. A fall in lymphocyte count at the time of tumor development is attributed to the loss of B lymphocytes which spontaneously incorporate [3H]thymidine.
Transmission of hepatitis B to chimpanzees by hepatitis B surface antigen-positive saliva and semen
Authors: Alter H J , Purcell R H , Gerin J L , London W T , Kaplan P M , McAuliffe V J , Wagner J , Holland P V
Published: January 2020

To assess the infectivity of hepatitis B surface antigen (HBsAg)-containing body fluids other than blood, chimpanzees were inoculated intravenously with saliva and semen obtained from HBsAg-positive individuals implicated in non-percutaneous transmission of hepatitis B. Saliva and semen samples were negative for occult blood. The titer of HBsAg in saliva was on the average only 1/3,000 that of the corresponding serum. One chimpanzee, inoculated sequentially with saliva from three individuals, developed HBsAg at 9 weeks and serum glutamic pyruvic transaminase elevation at 13 weeks after injection. HBsAg persisted for 15 weeks. This animal also developed e antigen, anti-core antibody, and anti-surface antibody. Liver biopsies showed acute hepatitis that subsequently resolved. A second chimpanzee, inoculated with HBsAg-positive semen, developed HBsAg and elevated serum glutamic pyruvic transaminase 4 weeks after inoculation and then died suddenly without explanation. HBsAg was positive in two consecutive samples and was confirmed by specific neutralization. Autopsy did not reveal evidence of hepatitis. This study demonstrates that HBsAg-positive saliva and, probably, semen contain infectious virus and suggests that saliva and/or semen may serve as important mechanisms in the transmission of type B hepatitis.
Patterns of loss of enterotoxigenicity by Escherichia coli isolated from adults with diarrhea: suggestive evidence for an interrelationship with serotype
Authors: Evans D J , Evans D G , DuPont H L , Orskov F , Orskov I
Published: January 2020

Enterotoxigenic Escherichia coli isolates obtained in Mexico from adult subjects with diarrhea and from healthy controls were examined for the production of heat-stable enterotoxin (ST) and heat-labile enterotoxin (LT) after serial passage in the laboratory. Isolates were found to be either stable for the production of ST and LT or unstable with respect to ST, LT, or both. Unilateral loss of either ST or LT production allowed classification of E. coli isolates into four groups according to stability/instability of enterotoxin production. Fewer serotypes, with more representative isolates, were in group I (stable) than in group IV (completely unstable). Isolates from Dacca, Bangladesh, could be similarly classified into stability groups. There is an apparent relationship between serotype, stability of enterotoxin production, particularly LT, and isolation from diarrhea cases as opposed to isolation from healthy controls.
Chemiluminescence by human alveolar macrophages: stimulation with heat-killed bacteria or phorobol myristate acetate
Authors: Beall G D , Repine J E , Hoidal J R , Rasp F L
Published: January 2020

Chemiluminescence of human alveolar macrophages (AM) was evaluated in vitro. Unstimulated AM generated chemiluminescence that remained constant during incubation. Addition of heat-killed Staphylococcus aureus 502A (HKB) or a chemical agent, phorbol myristate acetate, produced high rates of chemiluminescence that were significantly (P less than 0.05) increased over unstimulated AM. Phorbol myristate acetate-and HKB-stimulated increases in AM chemiluminescence were completely blocked by the enzyme superoxide dismutase. In comparison with unstimulated polymorphonuclear leukocytes, unstimulated AM had significantly (P less than 0.005) greater levels of chemiluminescence. However, after stimulation by phorbol myristate acetate or HKB, AM showed less chemiluminescence than similarly treated polymorphonuclear leukocytes.
Production of extracellular material by streptococci associated with subacute bacterial endocarditis
Authors: Straus D C , Mattingly S J , Milligan T W
Published: January 2020

Six strains of viridans streptococci isolated from confirmed cases of subacute bacterial endocarditis were studied for production of extracellular material. All six strains, when grown to the exponential phase, produced exoproducts that had similar elution profiles on a G-100 Sephadex column. Since essential nutrients, such as amino acids, may be periodically growth limiting to streptococci in the fibrin-covered lesions on heart valves, the potential to elaborate extracellular protein and other material by streptococci that were deprived of essential amino acids was studied. Examination of supernatant fluids from cultures of Streptococcus MG intermedius deprived of glutamate and cystine revealed the presence of a complex mixture of extracellular materials in amounts comparable to those produced by normallly growing cells, Although only a slight (21 to 24%) increase in total protein occurred during amino acid deprivation of 12 h, the extracellular material contained numerous protein components, several of which demonstrated proteolytic activity. On a cell dry weight basis, the amino acid-deprived cells produced four-to eightfold more protease(s) than did exponential cells grown in complete medium. These results demonstrate that viridans streptococci are capable of elaborating potentially damaging compounds even when their multiplication has been arrested by nutritional deprivation.
Parasitism by Virulent
Treponema pallidum
of Host Cell Surfaces
Authors: Hayes N. S. , Muse K. E. , Collier A. M. , Baseman J. B.
Published: January 2020

The interaction between virulent
Treponema pallidum
extracted from infected rabbit testes and animal cells in culture was examined. The extent of treponemal attachment to monolayers of normal rabbit testicular and HEp-2 cells was dependent upon the incubation temperature and retained motility of the spirochetes. The specific orientation of treponemes to host cell surfaces was demonstrated by dark-field microscopic examination of wet-mount preparations and scanning and transmission electron microscopy. Once attached,
T. pallidum
organisms remained actively motile yet anchored in place by their terminal tapered structures. After several hours of co-incubation, maximal attachment was attained, and the degree of parasitism seemed regulated not only by available surface sites on individual host cells but also by the proposed membrane response of parasitized cells to continued exposure to treponemes. The avirulent strain,
Treponema phagedenis
biotype Reiter, did not adhere to monolayer cultures. Characterization of host cell determinants that permitted surface colonization by
T. pallidum
was attempted. Also, properties of virulent treponemes that enabled surface parasitism were monitored by measuring the effects of enzymes, detergents, and metabolic inhibitors on the host-parasite interaction. Results reinforced the specific nature of the treponemal attachment mechanism. Furthermore, the ability of convalescent rabbit sera to reduce attachment of treponemes to host cells suggested that surface structures on
T. pallidum
could be masked or inactivated by host components, thus providing a potentially effective research approach for investigating the pathogenesis of syphilis and screening appropriate vaccine candidates.
Effects of stimulation and suppression of cell-mediated immunity on experimental cryptococcosis
Authors: Diamond R D
Published: January 2020

A model of cryptococcosis was developed using intraperitoneal infections of guinea pigs. This model shared characteristics with cryptococcosis in humans and was used to study the effects of immunosuppression and immunostimulation on cryptococcosis. Female guniea pigs survived longer than males; perphaps this was related to a greater capacity of their monocytes to kill cryptococci. A brief course of cortisone shortened survival of females and resulted in depressed immune and inflammatory responses, which persisted long after cortisone was stopped. Stimulation of the immune response by treatment with cryptococci in Freund complete adjuvant improved survival in males. Preliminary studies indicated the usefulness of this model for the study of other potential immunostimulants, including immune lymphocytes, transfer factor prepared from immune lymphocytes, and levamisole. Overall, long-term survivors appeared to clear disseminated cryptococci from extraperitoneal sites including brain, rather than prevent dissemination of cryptococci from the peritoneal cavity. The quantity of the inflammatory response in infectious foci, rather than the ability of individual leukocytes to kill crytococci, may have determined the outcome of most infections.
Survey of the extrachromosomal gene pool of Streptococcus mutans
Authors: Macrina F L , Reider J L , Virgili S S , Kopecko D J
Published: January 2020

Fifty strains of Streptococcus mutans independently isolated from human dental plaque were examined for the presence of covalently closed circular plasmid deoxyribonucleic acid (DNA). Cesium chloride-ethidium bromide centrifugation of [3H]thymidine-labeled, Sarkosyl-lysed cells revealed that 2 of the 50 strains contained plasmid DNA. The plasmid DNA from these strains was characterized by velocity and equilibrium centrifugation and by electron microscopy. The plasmids in these strains were virtually identical in size, with molecular weights of 3.6 X 10(6) and 3.7 X 10(6), Both were present to the extent of approximately 20 molecules per genome equivalent. Interlocked catenated dimeric molecules of each plasmid were readily detected by velocity sedimentation and electron microscopy. These plasmid-containing strains were compared with representative plasmid-free S. mutans strains by using such criteria as bacteriocin production, antibiotic susceptibility, and hemolysis of mammalian erythrocytes. Although no correlation of phenotype to plasmid content could be made, production of bacteriocin-like activity differed significantly between the two plasmid-containing S. mutans isolates. Thus, although the plasmids in these two isolates appeared identical by the criteria of molecular weight, presence of dimers, and copy number, they appeared to be harbored by two distinct S. mutans strains.
Effect of oil composition on both adjuvant-induced arthritis and delayed hypersensitivity to purified protein derivative and peptidoglycans in various rat strains
Authors: Kohashi O , Pearson M , Beck F J , Alexander M
Published: January 2020

We confirmed that, when immunized with a conventional complete Freund adjuvant (water in oil), Lewis rats were highly susceptible to adjuvant arthritis, Fisher rats were less susceptible, and Buffalo rats were much less susceptible. However, mycobacterial delipidated cells in squalane (squalane-type adjuvant) produced severe arthritis with almost 100% incidence even in the less susceptible rat strains except for Buffalo rats. With regard to an immune response, Freund complete adjuvant induced strong delayed hypersensitivity to purified protein derivative (PPD) and peptidoglycan (PG) in all rat strains used, Whereas the squalane-type adjuvant induced these hypersensitivities only in Lewis and Buffalo rats, but not in Fisher and Brown Norway rats. No correlation was found between development of arthritis and delayed hypersensitivity to either PPD or PG, or both. It seems that PPD hypersensitivity may be inherited differently from PG hypersensitivity.
Effect of silica on the pathogenic distinction between herpes simplex virus type 1 and 2 hepatitis in mice
Authors: Mogensen S C , Andersen H K
Published: January 2020

The role of macrophages in the difference in liver pathogenicity between herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) in mice was investigated by selectively blocking the macrophage function of the mice by silica. Intravenous administration of 3 mg of silica 2 h before virus inoculation partially abolished the difference between the two virus types, as judged by macroscopic and microscopic examination of the livers and by virus isolation studies. Intraperitoneal inoculation of 50 mg of silical before virus seemed more effective in suppressing the macrophage function, since this treatment almost completely eliminated the difference in hepatotropism between HSV-1 and HSV-2 as assessed by the number and size of the lesions appearing in the liver. The final outcome of the infection, death from encephalitis, was, however, not influenced by macrophage blockade.
Infection of HeLa cells with Salmonella typhimurium 395 MS and MR10 bacteria
Authors: Kihlström E
Published: January 2020

After interaction with HeLa cells cultured in vitro, the fraction of adhering extracellular and that of internalized smooth Salmonella typhimurium 395 MS and rough 395 MR10 have been determined by two different techniques. (i) By using the indirect fluorescent-antibody technique on unfixed and acetone-fixed HeLa cell preparations, intracellular bacteria were considered to become stained only after acetone fixation. (ii) Based on the assumption that gentamicin affects only extracellular bacteria, disintegration of the infected HeLa cells and viable count allowed the determination of internalized bacteria. Both techniques showed that MS as well as MR10 bacteria gained intracellular access, the fraction of MR10 cells doing so being much greater. The net increase in the intracellular bacterial population was small within 3 h of incubation.
Congenital abnormalities in newborn calves after inoculation of pregnant cows with Akabane virus
Authors: Kurogi H , Inaba Y , Takahashi E , Sato K , Satoda K
Published: January 2020

A fresh isolate of Akabane virus was inoculated intravenously into 11 seronegative pregnant cows at 62 to 96 days of gestation. Two of the cows were slaughtered 18 days post-inoculation, and the fetuses were examined; the remaining cows were allowed to give birth. All the inoculated cows developed viremia and neutralizing antibody for the virus, indicating that the cows were actually infected with the virus, although fever or any other clinical abnormalities were not noted. The virus further infected the fetuses. This was proved by virus isolation in one of the two fetuses from the slaughtered cows, and polymyositis was noted in both fetuses. Six of seven calves born alive had anti-Akabane antibody in their precolostral sera, indicating that in utero infection with the virus took place in these calves. Some of the in utero-infected calves demonstrated congenital abnormalities such as cerebral defect, hydranencephaly, and arthrogryposis. These findings provide additional evidence that Akabane virus is the etiological agent of epizootic abortion and congenital arthrogryposis-hydranencephaly syndrome in cattle.
Evaluation of vascular clearance as a marker for virulence of alphaviruses: disassociation of rapid clearance with low virulence of venezuelan encephalitis virus strains in guinea pigs
Authors: Jahrling P B , Heisey G B , Hesse R A
Published: January 2020

The concept that relates low virulence of certain alphaviruses to low viremia and efficient vascular clearance of virus was tested in guinea pigs. Previously published studies with hamsters suggested that virulent strains maintain high viremias primarily because they are cleared inefficiently from the blood. In the present study, with guinea pigs, six of six virulent strains of Venezuelan encephalitis virus were cleared inefficiently, whereas three of six nonlethal or benign virus strains were cleared rapidly. However, three other guinea pig-benign Venezuelan encephalitis virus strains cleared slowly, to produce a high viremia was correlated with inefficient growth in primary viral replication sites. Thus, the potential of some alphaviruses to produce destructive lesions may be restricted by efficient clearance of virus from the blood, whereas the growth of other benign alphavirus strains may be restricted after the virus is presented to target cells.
Ultrastructural Localization of Sucrases in
Streptococcus mutans
GS-5 and an Extracellular Polysaccharide Mutant: a Comparative Cytochemical and Immunocytochemical Study
Authors: Bozzola J. J. , Johnson M. C. , Shechmeister I. L.
Published: January 2020

Electron microscopy and cytochemical and immunocytochemical procedures were used to study the ultrastructural distribution of sucrase enzymes in two strains of
Streptococcus mutans
. In a strongly adherent and virulent parent strain, GS-5, most of the invertase and fructosyltransferase activities were demonstrated extracellularly or bound to the cell surfaces. Intracellularly, enzymatic sites were detected near the plasma membrane on the periphery of the nucleoid and central mesosome. In GS-511, a mutant of diminished virulence and adherence, most of the enzymatic activity was not located on the cell surfaces, but was found away from the cell walls and associated with extracellular polysaccharides. Intracellularly, GS-511 manifested the same distribution of invertase and fructosyltransferase as did GS-5; however, the close association of these enzymes with the plasma membrane was not shown in GS-511. In both strains, extracellular areas near regions associated with cross wall formation appeared to show localized concentrations of these sucrases. Antibodies against partially purified glucosyltransferase (GTF) enzymes from GS-5 were used to localize GTF by immunocytochemical techniques. Indirect ferritin localization procedures showed that the extracellular and cell-bound GTF enzymes were distributed in similar locations as the fructosyltransferase and invertase enzymes. By absorption of the antiserum with whole GS-511 cells, the location of extracellular GTF and surface antigens unique to GS-5 was demonstrated. The dramatically reduced levels of cell-bound sucrase activity in GS-511 indicates the significant role of these enzymes in adherence and cariogenicity.
Effect of warfarin on the induction and course of experimental Staphylococcus epidermidis endocarditis
Authors: Thörig L , Thompson J , Eulderink F
Published: January 2020

The effect of warfarin treatment on an experimental Staphylococcus epidermidis endocarditis was studied. Warfarin was found to affect both the induction and course of the infection of catheter-induced endocardial vegetations. In warfarin-treated rabbits, larger bacterial inocula were needed to induce an infection, and the degree of infection of the vegetations was also significantly lower, eventually resulting in the total elimination of the bacteria from the vegetations. Thus, warfarin treatment seems to have an inhibitory effect on the induction and development of an S. epidermidis infection of the endocardium. The results differ from previous findings in studies done with Streptococcus anguis, where warfarin was found to have no effect on the induction or course of the infection of endocardial vegetations, which suggests that different mechanisms are involved in the pathogenesis of endocarditis caused by these two species of bacteria.
Chemiluminescence Response of Human Leukocytes: Influence of Medium Components on Light Production
Authors: Nelson Robert D. , Herron Michael J. , Schmidtke Jon R. , Simmons Richard L.
Published: January 2020

Light-producing reactions have been reported to occur after phagocytosis of opsonized particles by human polymorphonuclear neutrophils, eosinophils, and monocytes. Such chemiluminescence appears to be related to the generation of singlet oxygen, superoxide, and hydroxyl radicals, which have also been implicated as microbicidal agents. In examining the influences of various medium components on leukocyte chemiluminescence, we have observed that the amount of light measured is increased by addition of soluble protein, the amino acids tyrosine and tryptophane, or excess zymosan to the reaction medium. These agents appear to produce their effect not by increasing the rate of phagocytosis, but by providing substrate for secondary light-producing reactions. Polystyrene particles do not provide a suitable substrate for such secondary light-producing reactions. This is evidenced by the failure of ingested latex to stimulate high levels of chemiluminescence in the cellular system and their failure to augment light production in two noncellular chemiluminescent reactions. Some of the light generated in the cellular chemiluminescence response may derive from secondary reactions, which occur outside of the phagocyte. Support for this phenomenon is provided by two experiments. In one, addition of supplementary, nonopsonized zymosan to the reaction, after phagocytosis of opsonized zymosan is complete, resulted in an increased level of chemiluminescence. In another, addition of nonopsonized zymosan, together with latex particles, resulted in a significant increase in chemiluminescence. The results of the latter experiment also support our hypothesis that latex does not provide an appropriate substrate for secondary light-producing reactions. These observations suggest that leukocytes activated by phagocytosis generate electronically activated radicals which act intra- and extracellularly and that the amino acids tyrosine and trytophane may provide one substrate through which these agents act.
Inability of spleen cells from chancre-immune rabbits to confer immunity to challenge with Treponema pallidum
Authors: Baughn R E , Musher D M , Simmons C B
Published: January 2020

Although several lines of evidence suggest that cellular immune mechanisms play a role in controlling infection due to Treponema pallidum, recent studies have shown that induction of acquired cellular resistance by antigenically unrelated organisms fails to protect rabbits against syphilitic infection, thereby casting doubt on this hypothesis. In the present paper we describe attempts to transfer immunity to syphilis by using spleen cells from chancre-immune rabbits. Intravenous infusion of 2 X 10(8) spleen lymphocytes was capable of transferring acquired cellular resistance to Listeria and delayed hypersensitivity to tuberculin. However, in eight separate experiments using outbred or inbred rabbits, 2 X 10(8) spleen cells from syphilis-immune animals failed to confer resistance to T. pallidum whether by intravenous or intradermal challenge. Mixing immune lymphocytes with treponemes immediately before intradermal inoculation also failed to confer resistance. Despite the fact that syphilitic infection stimulates cellular immune mechanisms and induces acquired cellular resistance to antigenically unrelated organisms, cellular immunity may not play an important role in immunity to syphilis.
Assessment of Typhoid Vaccines by Using the Intraperitoneal Route of Challenge
Authors: Carter Philip B. , Collins Frank M.
Published: January 2020

Present laboratory tests for human typhoid vaccines use an intraperitoneal route of challenge given 7 days after injection of increasing doses of standard and test vaccines by the same route. In studies reported here, groups of B6D2 mice were vaccinated intraperitoneally with 2 × 10
8
acetone-killed
Salmonella typhi
Ty2, with the Vi antigen-free variant O-901, or with
Yersinia enterocolitica
and
Serratia marcescens
suspensions. Other groups of mice received 200 μg of purified
S. typhi
or
S. marcescens
endotoxin, or their corresponding purified lipid A components. All of the vaccinated mice (except for saline- or thioglycolate-injected controls) exhibited increased protection against the lethal intraperitoneal challenge with
S. typhi
Ty2. Serial quantitative bacterial counts carried out on peritoneal washouts and on homogenates of the draining mediastinal lymph nodes indicated the development of an antibacterial response by the vaccinated host which was not observed in the control animals. Mice receiving purified endotoxin (lipopolysaccharide) exhibited varying degrees of protection, both in terms of increased host survival and the amount of inactivation of the challenge population in vivo. The response seen when the antigenically unrelated
S. marcescens
lipopolysaccharide was injected was little different from that seen when the acetone-killed
S. typhi
Ty2 whole-cell vaccine was used. This suggests that nonspecific inactivation of the intraperitoneal challenge contributes substantially to the immune response seen in mice vaccinated intraperitoneally with specific typhoid antigens.
Cell-mediated immunity to Nocardia asteroides induced by its ribonucleic acid protein fraction
Authors: Sundararaj T , Agarwal S C
Published: January 2020

Guinea pigs immunized with ribonucleic acid protein fraction from Nocardia asteroides developed high cell-mediated immunity within 2 weeks, as shown by increased macrophage microbicidal activity and macrophage migration inhibition. This immunity protected against intravenous and subcutaneous challenge with N. asteroides and persisted for at least 70 days.
Virus-Induced Specific Cell Surface Antigen(s) on Mouse Adenovirus-Infected Cells
Authors: Inada Toshiki , Uetake Hisao
Published: January 2020

A virus-specific cell surface antigen(s) was detected on mouse adenovirus-infected cells by the immunofluorescent antibody technique. It was demonstrated in infected cells regardless of the mouse strain or animal species used. It became detectable on the cell surface about 6 h postinfection and was demonstrated in 90% of infected cells at 24 to 36 h postinfection. On the other hand, intracellular capsid antigens became detectable by the immunofluorescent antibody technique at about 24 h postinfection. Since it was also detected on virus-infected cells treated with 5′-fluorodeoxyuridine to block viral deoxyribonucleic acid synthesis, it was synthesized at the early stage of infection and may not be a virus structural component. The relationship between this serologically detectable cell surface antigen(s) and cell-mediated immune response to virus infections is discussed.
Effect of Heat on Antigenicity and Immunogenicity of the Antigenic Determinant Shared by
Haemophilus influenzae
Type b and
Escherichia coli
K100
Authors: Whang H. Y. , Goldhar J. , Neter E.
Published: January 2020

Escherichia coli
K100 produces an antigenic determinant similar to, or identical with, the capsular antigen of
Haemophilus influenzae
type b. Studies of the effects of heat on the immunogenicity, erythrocyte-modifying capacity, and antigenicity of this cross-reacting antigen (CRA) revealed the following findings. Immunization of rabbits with viable or formaldehyde-killed suspensions of
E. coli
K100, producing CRA, engendered CRA antibodies in significant titers, as demonstrated by hemagglutination of erythrocytes modified by
H. influenzae
type b antigen. Heating of the suspensions for 1 h at 56 or 100°C destroyed the immunogenicity of CRA, and the heated suspensions did not prime for a secondary antibody response. Supernatants of heated suspensions also were non-immunogenic. Repeated freezing and thawing of heated suspensions of
E. coli
K100 or their supernatants did not restore immunogenicity. Heat also abolished the immunogenicity of
H. influenzae
type b. The loss of immunogenicity of CRA of
E. coli
K100 by heat was not due to alteration of the antigenic determinant, since heated suspensions and supernatants thereof modified erythrocytes for agglutination by
H. influenzae
type b antiserum. The latter supernatants also inhibited hemagglutination by
H. influenzae
type b antibodies and absorbed the latter. We conclude that striking differences exist in the effects of heat on CRA on the one hand and of enterobacterial common antigen and lipopolysaccharide O antigen of enteric bacteria on the other. Heating of the latter two antigens does not abolish their priming effect, and repeated freezing and thawing restores the immunogenicity of heated antigens.