bluuebunny/crossref_metadata_2025 huggingface dataset:
Chlamydia psittaci elementary body envelopes: ingestion and inhibition of phagolysosome fusion
Authors: Eissenberg L G , Wyrick P B , Davis C H , Rumpp J W
Published: January 2020

The cell surface of Chlamydia psittaci seems important for establishing infection since (i) UV-treated elementary bodies (EB) attach to and are ingested by L cells and (ii) heat or antibody treatment decreases attachment to L cells and promotes the fusion of chlamydiae-containing phagosomes with lysosomes in macrophages. In the studies reported here, [3H]uridine-labeled UV-treated EB also persisted in mouse resident peritoneal macrophages and L cells, suggesting that phagosome-lysosome fusion is inhibited. We therefore chose to investigate the ingestion and internal fate of isolated purified EB envelopes in both nonprofessional and professional phagocytic cells. EB envelopes are internalized by target host cells as efficiently as are whole EB. Transmission electron microscopy of macrophages whose lysosomes were marked with ferritin revealed the persistence of individual envelopes in phagosomes devoid of ferritin for the 3-h observation period. In contrast, EB envelopes heated to 56 degrees C for 15 min were consistently found in ferritin-labeled phagolysosomes as early as 30 min. As another index of persistence, isolated EB envelopes were radioisotopically labeled with a Bolton-Hunter analog, [3H]N-succinimidyl propionate, and their fate as trichloroacetic acid-precipitable material was followed. A third probe, employed to detect the persistence of non-biodegradable antigen, was indirect immunofluorescence. Fluorescein-positive antigens were brightly visible for 7 days in both macrophages and L cells when they were inoculated with untreated EB or EB maintained in penicillin. But L cells inoculated with EB envelopes or EB treated with UV or chloramphenicol, all of which prevent the conversion of infectious EB into the metabolically active reticulate bodies, displayed reduced internal fluorescence by 2 days and the appearance of fluorescent material on the cell surface. This release of EB envelope material occurred in the absence of phagolysosome fusion. The data add credence to the belief that the spontaneous breakdown or autolytic enzyme release of EB envelope components must occur preparatory to the conversion of EB to reticulate bodies.
Comparison of proteins synthesized by two different isolates of Anaplasma marginale
Authors: Barbet A F , Anderson L W , Palmer G H , McGuire T C
Published: January 2020

We present results on the initial definition of proteins synthesized by two isolates of Anaplasma marginale. Bovine erythrocytes infected with A. marginale were radioactively labeled with [35S]methionine or a 3H-amino acid mixture during short-term in vitro culture. The labeled proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This technique revealed protein bands of various apparent molecular weights from less than 14,000 to greater than 200,000. The bands observed represented A. marginale proteins because (i) uninfected erythrocytes from the same animal did not incorporate radioisotope during identical culture conditions, and (ii) the incorporation of radioisotope into proteins during culture of infected erythrocytes was inhibited by tetracycline but not by cycloheximide. The radioactive protein profiles of two different isolates of A. marginale, from Washington and Florida, were compared by two-dimensional gel electrophoresis. About 200 proteins were resolved in each case. Several proteins differed in position when the two-dimensional gel maps were compared, indicating variations in protein structure between the two A. marginale isolates.
Secretory immunological response after intranasal inactivated influenza A virus vaccinations: evidence for immunoglobulin A memory
Authors: Wright P F , Murphy B R , Kervina M , Lawrence E M , Phelan M A , Karzon D T
Published: January 2020

An intranasal, inactivated trivalent influenza A vaccine containing 7 micrograms of A/Bangkok/1/79 (H3N2) hemagglutinin was administered to 20 children aged 1 to 6 years to assess the local and systemic immune responses to antigen delivered to the respiratory tract. Six children without prior influenza virus infection exhibited no local immune response and manifested only a minimal systemic response to the intranasal vaccine. In contrast, five individuals who were previously infected with a live attenuated influenza A H3N2 virus vaccine, although having no residual secretory antibody at the time of challenge, promptly developed a local antibody response to intranasal, inactivated antigen. Therefore, the live influenza A virus vaccine had induced memory in the local immunoglobulin A (IgA) immune system. The third group of nine children had previously been infected with wild-type H3N2 influenza virus. A majority of these children had residual local and systemic antibody at the time of challenge but they demonstrated some boosting of local IgA antibody with administration of intranasal inactivated vaccine. The competence of the secretory IgA immune system in young children in mounting primary and secondary responses to influenza antigens has important implications for approaches to prevention of influenzal illness.
Protoplast formation and localization of enzymes in Streptococcus mitis
Authors: Linder L , Andersson C , Sund M L , Shockman G D
Published: January 2020

Cells of Streptococcus mitis ATCC 903 were converted to stable protoplasts by the cell wall-degrading M-1 enzyme of the mutanolysin complex isolated from Streptomyces globisporus. Over 90% of total glucokinase (EC 2.7.1.2), aminopeptidase (EC 3.4.11.1), and dextranglucosidase (EC 3.2.1.70) was recovered in the cytoplasmic fraction, whereas over 20% of total invertase (beta-fructofuranosidase: EC 3.2.1.26) was released during protoplast formation. ATPase (EC 3.6.1.3). chymotrypsin-like protease (EC 3.4.21.1), arginine aminopeptidase (EC 3.4.11.6), and lactate dehydrogenase (EC 1.1.1.27) were detected in Triton X-100 extracts of the cytoplasmic membrane fraction by crossed immunoelectrophoresis in combination with enzyme-staining procedures. By these methods, NADH dehydrogenase (EC 1.6.99.3), aminopeptidase, and lactate dehydrogenase were detected in the cytoplasmic fraction. Aminopeptidases in the cytoplasmic fraction differed from this activity in the membrane fractions in electrophoretic mobility and substrate specificity.
Serotypes of bovine rotaviruses distinguished by serum neutralization
Authors: Murakami Y , Nishioka N , Hashiguchi Y , Kuniyasu C
Published: January 2020

Fourteen cytopathic bovine rotaviruses isolated from naturally affected calves were characterized serologically by serum neutralization. Antisera were prepared in guinea pigs against the three isolates and the Lincoln strain of bovine rotavirus. These four rotaviruses were segregated into at least two distinct serotypes (designated types 1 and 2) by serum neutralization. The remaining 11 isolates were also placed into two groups according to neutralization specificity by using the antisera against types 1 and 2 bovine rotavirus. When colostrum-deprived calves were experimentally inoculated with type 1 or 2 bovine rotavirus, respectively, the calves produced neutralizing antibodies against the inoculated serotype but not against the other serotype. Calf sera obtained from six herds with naturally occurring rotavirus infections possessed neutralizing antibodies against type 1 or 2 or both. Thus, distinct serotypes of bovine rotavirus were demonstrated by serum neutralization. The possible role of serotypes in the epidemiology of rotavirus infection among bovine species is discussed.
Natural killer activity in mice infected with Trypanosoma musculi
Authors: Albright J W , Huang K Y , Albright J F
Published: January 2020

Trypanosoma musculi infection affected natural killer (NK) activity in mice. In the spleen, an increase of two to three times normal was displayed on days 2 to 4 after inoculation of parasites, followed by rapid decline to a subnormal level of activity that persisted for more than 3 weeks and included the phase of rapid parasite elimination. NK activity increased dramatically in peritoneal exudate and marrow early in infection, but the subsequent decline was more moderate than in the spleen. The subnormal splenic activity was not elevated by treating infected mice with an interferon inducer, polyinosinic acid-polycytidylic acid. Serum interferon levels were elevated early in infection, but by day 4 postinoculation, they had returned to undetectable. Injection of mice with antiserum to murine interferon-beta did not inhibit the early rise in NK activity or alter the course of trypanosome infection; in fact, the antiserum treatment enhanced splenic NK activity in infected mice. The early rise and subsequent decline of NK activity did not correlate with the course of T. musculi infection and subsequent cure. The cause of the dramatic decline in splenic NK activity is under investigation; it could result, for example, from arousal of suppressor cells, inhibition by prostaglandins, or inhibition by trypanosome-derived substances. Thus, NK cells may be prevented from fulfilling their potential of attacking the extracellular trypanosomes by the effects of inhibitory substances.
Inbred mouse strains differ in resistance to lethal Coccidioides immitis infection
Authors: Kirkland T N , Fierer J
Published: January 2020

Inbred strains of mice were infected intraperitoneally with Coccidioides immitis, and the mean lethal dose was determined after 28 days. DBA/2N mice had a mean lethal dose of greater than 10(5) arthroconidia, whereas BALB/cAnN, C57BL/6N, and C57L/J mice had a mean lethal dose of less than or equal to 10(3). Since both BALB/c and DBA/2 mice are the H-2d haplotype, resistance is not primarily determined by the major histocompatibility locus. Resistance was the dominant phenotype. The pattern of C. immitis-resistant strains does not correspond to the strain distribution of the lsh gene or to the pattern of resistance to Blastomyces dermatitidis or Cryptococcus neoformans. Both resistant and susceptible mice, however, could be successfully immunized with a killed spherule vaccine, and susceptible BALB/cAnN mice were protected from an otherwise lethal infection by prior immunization with an attenuated mutant of C. immitis. Despite the evidence that BALB/cAnN mice could respond to immunization, nonimmune mice did not control the later phase of intraabdominal infection as well as DBA/2N mice. Dissemination of C. immitis to the lung occurred frequently in BALB/cAnN but not in DBA/2N mice. This suggests that BALB/cAnN mice cannot mount an effective immune response to C. immitis during the course of infection.
Dextran-induced aggregation in a mutant of Streptococcus sobrinus 6715-13
Authors: Freedman M L , Guggenheim B
Published: January 2020

A mutant of wild-type Streptococcus sobrinus 6715-13 has been isolated which resists aggregation by exogenous dextran. This variant is able to form adherent plaque deposits in vitro when cultured in the presence of sucrose and has dextranase activity. In these respects it is the complement of previously described isolates which are plaque formation defective but aggregation normal. Measurements of the incorporation of glucose from glucosyl-labeled sucrose into glucan by cell-associated glucosyltransferase enzyme activity and the thermal labilities of catalytic and receptor functions, as well as the binding of labeled dextrans to the cells, provide evidence that neither dextranase nor glucosyltransferase is the receptor involved in dextran-induced aggregation. Blockage of such bacterial aggregation by anti-glucosyltransferase or anti-dextranase sera suggests cross-reactivity between the antigenic determinants of proteins which recognize alpha(1-6) glucan linkages. A model is proposed, consistent with these and previous findings, in which enzymatic function precedes dextran receptor activity in emergence from the cell. It is also proposed that dextran receptor components of the multireactive glucosyltransferase enzyme(s) and dextranase(s) are spatially separate from, although functionally and antigenically related to, the receptors on the bacterial surface involved in dextran-induced aggregation.
Candida albicans-induced agglutinin and immunoglobulin E responses in mice
Authors: Winterrowd G E , Cutler J E
Published: January 2020

Mice varied in their ability to make detectable antibody responses to cell surface determinants of Candida albicans depending upon the antigen preparation and the immunization schedule used. Immunoglobulin M (IgM) appeared to be the major class of antibody responsible for the C. albicans-agglutinating activity of the immune sera. Various inbred strains of mice injected with a ribosomal fraction from C. albicans produced a low titer (average, 4 to 8) of yeast cell agglutinins and a higher titer (64 to 512) of IgE antibodies detected by passive cutaneous anaphylaxis (PCA) in rats. The two kinds of antibodies appeared to be specific for different antigens because the agglutinin, but not IgE, could be removed by absorbing the serum with a polysaccharide from the cell wall of C. albicans, but the polysaccharide did not provoke the PCA reaction. C. albicans-specific IgE antibodies showed cross-reactivity (PCA) with ribosomal antigens from a strain of C. albicans and C. tropicalis, but PCA reactions could not be elicited with similar antigen preparations from other yeast species. IgE responses were also detected in over 20% of the mice infected intravenously or intraperitoneally with live C. albicans.
Evidence that a new enterotoxin of Escherichia coli which activates adenylate cyclase in eucaryotic target cells is not plasmid mediated
Authors: Green B A , Neill R J , Ruyechan W T , Holmes R K
Published: January 2020

Escherichia coli SA53 produces a new enterotoxin that has a biological activity similar to that of E. coli heat-labile enterotoxin (LT) but is not neutralized by antiserum against LT or cholera enterotoxin. Strain SA53 contained two plasmids, pRB1 (69.2 +/- 4.3 megadaltons) and pRB2 (57.6 +/- 5.3 megadaltons). Studies were undertaken to determine whether either plasmid was required for production of the LT-like toxin. We isolated a derivative of SA53 lacking both plasmids and confirmed that radioactively labeled pRB1 and pRB2 DNAs failed to hybridize to total DNA digests of the cured strain. The new enterotoxin was still produced by the cured strain, demonstrating that the gene(s) encoding the toxin was not located on pRB1 or pRB2 and was most likely on the bacterial chromosome. Although sonic extracts from SA53 contained no detectable LT antigen, plasmid pRB1 DNA did contain sequences with partial homology to the LT-A and LT-B genes. No sequence homology with LT genes was detected with pRB2 DNA. When the enterotoxin plasmid pCG86 was introduced into a rifampin-resistant derivative of SA53, LT was produced. Thus, plasmid-coded LT could be produced in the E. coli SA53 host, and the sequences homologous to LT in pRB1 were cryptic.
Danish children in Greenland have high Epstein-Barr virus titers
Authors: Ebbesen P , Melbye M , Levine P H , Andersen H K
Published: January 2020

Danish children brought to Greenland have somewhat higher mean titers of antibodies to Epstein-Barr virus than do Danish children in Denmark, although their titers are lower than those found in Eskimo children. This study presents the first evidence of increases in Epstein-Barr virus titers in migrant children.
Cloning and analysis of the K1 capsule biosynthesis genes of Escherichia coli: lack of homology with Neisseria meningitidis group B DNA sequences
Authors: Echarti C , Hirschel B , Boulnois G J , Varley J M , Waldvogel F , Timmis K N
Published: January 2020

Genes coding for production of the K1 polysaccharide capsule of Escherichia coli have been cloned. Complementation, insertion, and deletion analyses were used to localize the K1 genes and demonstrated that a minimum of 9 kilobases of DNA split into at least two gene blocks is involved in synthesis and assembly of the capsule. One of the gene blocks is responsible for biosynthesis of the polysaccharide, and the other is responsible for extracellular appearance of capsular material. Using cloned K1 genes as probes in Southern blot experiments, we detected homology to DNA from strains of E. coli capsular types K92, K7, and K100. In contrast, no homology was apparent between K1 genes and DNA from meningococcus group B, although the K1 and group B capsules are chemically and immunologically identical.
Effect of dilution rate on lipopolysaccharide and serum resistance of Neisseria gonorrhoeae grown in continuous culture
Authors: Morse S A , Mintz C S , Sarafian S K , Bartenstein L , Bertram M , Apicella M A
Published: January 2020

Growth of Neisseria gonorrhoeae strain FA171 in continuous culture under glucose-limiting conditions resulted in a growth-rate-dependent change in the lipopolysaccharide (LPS). The evidence for this change is an alteration in the mobility of purified alkali-treated LPS on sodium dodecyl sulfate-polyacrylamide gels and a quantitative difference in the amount of the LPS serotype antigen. The LPS from cells grown at a low dilution rate (0.12 h-1) contained ca. eightfold less serotype antigen than the LPS from cells grown at a high dilution rate (0.56 h-1). The decrease in LPS serotype antigen was associated with an increase in sensitivity to the bactericidal activity of normal human serum and an increase in cell surface hydrophobicity. An increase in the amount of serotype antigen was associated with a reduction in the accessibility of a monoclonal antibody to a core LPS determinant, an increase in resistance to normal human serum, and a decrease in cell surface hydrophobicity. The microheterogeneity of gonococcal LPS with respect to the content of serotype antigen may result from an alteration in the metabolism of glucose.
Characterization of Chlamydia DNA by restriction endonuclease cleavage
Authors: Peterson E M , de la Maza L M
Published: January 2020

The DNA from six serovars of Chlamydia trachomatis, lymphogranuloma venereum (LGV) I, LGV II, LGV III, B, C, and D, and from Chlamydia psittaci was extracted, treated with restriction endonuclease enzymes, and run on agarose gels. By using this technique, the DNA of C. trachomatis could be clearly differentiated from C. psittaci DNA. A comparison of the DNA from the different serovars of C. trachomatis revealed similar patterns with and without detectable differences. LGV I, LGV II, LGV III, B, and C revealed no differences when treated with BamHI, HaeIII, XbaI, and XhoI. LGV III DNA, when cleaved with EcoRI and HhaI, had a major band migrating faster than the other two LGV serovars. Serovar D had a different pattern from all other strains tested when cleaved with BamHI, EcoRI, HhaI, HincI, and XhoI. When treated with SacI and HgaI, LGV II displayed a unique band not seen in the other LGV serovars. Differences in strains could be attributed to both chromosomal and plasmid DNA.
Comparison of major protein antigens and protein profiles of Treponema pallidum and Treponema pertenue
Authors: Thornburg R W , Baseman J B
Published: January 2020

The protein profiles of Treponema pallidum and Treponema pertenue, the causative agents of syphilis and yaws, respectively, were compared by one- and two-dimensional gel electrophoresis. One-dimensional gels showed essentially no differences in the protein patterns of these treponemes. On two-dimensional gels most radiolabeled protein species were shared; however, variations were noticed in several minor protein species. Antigenic comparison by radioimmunoprecipitation and Western blotting also demonstrated similarities between these spirochetes. However, lactoperoxidase-catalyzed iodination of T. pallidum and T. pertenue suggested differences in their surface proteins.
Enhancement of experimental ulcerative colitis by immunization with Bacteroides vulgatus
Authors: Onderdonk A B , Cisneros R L , Bronson R T
Published: January 2020

Previous studies with the guinea pig model for ulcerative colitis have shown that the inducing agent, carrageenan, does not provoke ulcerations in germfree guinea pigs, but animals monoassociated with Bacteroides vulgatus develop cecal ulcerations when fed carrageenan. In an effort to define the role of B. vulgatus in this model system, conventional guinea pigs were immunized with B. vulgatus before carrageenan treatment. Immunized animals developed both circulating antibody and positive skin tests for the homologous antigen. A comparison of B. vulgatus-immune and nonimmune carrageenan recipients after 30 days of carrageenan treatment revealed ulcerations of the ceca and large intestine in both groups, but the immune group developed more severe lesions than the nonimmune group. The most severe intestinal lesions were detected in B. vulgatus-immune animals fed both carrageenan and daily doses of viable B. vulgatus. Immune recipients of B. vulgatus alone did not develop ulcerations, but showed histological evidence of intestinal inflammation. Lesions observed in B. vulgatus-immune animals were most severe in the colon and rectum, in contrast to more severe cecal lesions detected in nonimmune carrageenan recipients. Similar experiments with Bacteroides fragilis as an antigen for immunization showed no difference between immune and nonimmune groups. These results suggest that immunization with B. vulgatus enhances the severity of carrageenan-induced colitis.
Cutaneous inflammatory reactions to group A streptococcal cell wall fragments in Fisher and Lewis inbred rats
Authors: Allen J B , Calandra G B , Wilder R L
Published: January 2020

Systemic administration of an aqueous suspension of group A streptococcal cell wall fragments induces severe, chronic erosive polyarthritis in LEW/N female rats, but rarely in F344/N female rats. In the present study, we attempted to exclude unresponsiveness to the cell walls as a mechanism for arthritis resistance in F344/N females. Cutaneous inflammatory reactions were assessed in both strains at various time points after direct injection of cell wall fragments of three different average molecular weights. Fragments of all sizes induced an acute inflammatory reaction, with infiltration of polymorphonuclear leukocytes and a few mononuclear cells. Small fragments (approximately 5 megadaltons) induced a transient response which resolved by day 14. Large fragments (approximately 500 megadaltons) induced severe inflammation characterized by prominent mononuclear leukocyte infiltration, whereas the intermediate-sized fragments (approximately 50 megadaltons) induced inflammation of intermediate intensity and duration. The intensity and severity of the lesions paralleled the persistence of cell wall antigens at the site of deposition. F344/N female rats responded acutely to the cell walls, with an intensity equal to or greater than that of LEW/N female rats, but the lesions tended to resolve more rapidly. These findings indicate that severity and chronicity of streptococcal cell wall-induced inflammation are dependent on the size of the fragment and provide evidence that arthritis resistance in F344/N female rats does not result from a completely unresponsive state to the proinflammatory effects of the cell walls.
Cell surface hydrophobicity of dental plaque microorganisms in situ
Authors: Rosenberg M , Judes H , Weiss E
Published: January 2020

The cell surface hydrophobicity of bacteria obtained directly from human tooth surfaces was assayed by measuring their adherence to liquid hydrocarbons. Fresh samples of supragingival dental plaque were washed and dispersed in buffer. Adherence of the plaque microorganisms to hexadecane, octane, and xylene was tested turbidimetrically and by direct microscopic observation. The results clearly show that the vast majority of bacteria comprising dental plaque exhibit pronounced cell surface hydrophobicity. These data support the hypothesis that hydrophobic interactions play a major role in mediating bacterial adherence on tooth surfaces.
Immunological properties of purified Klebsiella pneumoniae heat-stable enterotoxin
Authors: Klipstein F A , Engert R F , Houghten R A
Published: January 2020

Klebsiella pneumoniae heat-stable enterotoxin was purified to apparent homogenicity by the same techniques used to purify Escherichia coli heat-stable enterotoxin. The two toxins had the same potency in the suckling mouse assay and showed immunological cross-reactivity in enzyme-linked immunosorbent assay, neutralization of secretory activity by specific hyperimmune antisera, and protection against active challenge in rats immunized with a vaccine containing synthetically produced E. coli heat-stable enterotoxin.
Trypanosomiasis in mice with naturally occurring immunodeficiencies
Authors: Jones J F , Hancock G E
Published: January 2020

By using mice with naturally occurring defects, we have shown that an intact macrophage system is crucial to survival with the pathogenic protozoan Trypanosoma rhodesiense, since a defect in these cells decreased survival by half. Deficiencies in natural killer cell function or complement levels had no effect on survival. However, the capacity to survive trypanosomiasis was not related to the levels of parasitemia achieved during infection.
Effects of growth temperature, 47-megadalton plasmid, and calcium deficiency on the outer membrane protein porin and lipopolysaccharide composition of Yersinia pestis EV76
Authors: Darveau R P , Charnetzky W T , Hurlbert R F , Hancock R E
Published: January 2020

The expression of several virulence determinants of Yersinia pestis is known to be dependent on the in vitro growth temperature. One of these, calcium dependence, is associated with the presence of a 47-megadalton plasmid. We have examined the effects of incubation temperature, calcium in the growth medium, the presence of the 47-megadalton plasmid on the outer membrane protein, and the lipopolysaccharide composition of Y. pestis EV76. When cells were grown at 37 degrees C as opposed to 26 degrees C, a change in lipopolysaccharide composition and a decrease in the amount of an outer membrane protein (protein E) were observed. The lipopolysaccharide obtained from cells incubated at 37 degrees C had a lower proportion of 2 keto-3-deoxyoctanate, a lower phosphate to 2-keto-3-deoxyoctanate ratio, and an increased gel mobility upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis when compared with lipopolysaccharide obtained from cells grown at 26 degrees C. Because of its growth temperature-related abundance, we investigated the nature of protein E. This protein had physical properties similar to those of other enterobacterial porins, including apparent formation of an oligomer on sodium dodecyl sulfate-polyacrylamide gels when solubilized at low temperature, acidic isoelectric point, and strong noncovalent association with the peptidoglycan. Protein E was purified and shown to form an aqueous channel in planar lipid membranes with a conductance of 1.1 nS in 1 M KCl. In addition to growth temperature-related alterations in the lipopolysaccharide and porin components of the outer membrane, the amount of three spots in two-dimensional polyacrylamide gels was shown to be related to the temperature or the presence of calcium during growth. One of these spots was shown to contain residual unmodified portions of two major heat-modifiable proteins which failed to shift to their heat-modified positions on gels, despite solubilization at 100 degrees C for 10 min before electrophoresis. The other two spots were the heat-modified and unmodified forms of another outer membrane protein (J) which did not appear in the isoelectric focusing gel of cells grown at 37 degrees C. It is proposed that the appearance of these spots in two-dimensional analyses is related to the lipopolysaccharide composition of the cells from which the outer membrane is derived and reflects lipopolysaccharide-protein interactions or calcium-protein interactions.
Effect of Clostridium perfringens epsilon toxin on the cardiovascular system of rats
Authors: Sakurai J , Nagahama M , Fujii Y
Published: January 2020

Pressor activity was demonstrated by the intravenous injection of purified epsilon toxin of Clostridium perfringens type D but not by that of epsilon prototoxin. The activity was completely abolished by C. perfringens type B or D antiserum, but not by type A, C, or E antiserum. The rise in blood pressure caused by the toxin was accompanied by a decrease in the blood flow in skin without any change of heart rate and electrocardiogram readings. These results indicate that epsilon toxin possesses pressor activity as well as lethal and dermonecrotic activities.
Characterization of monoclonal antibodies that react with unique and cross-reacting determinants of cholera enterotoxin and its subunits
Authors: Holmes R K , Twiddy E M
Published: January 2020

Seventeen selected hybridoma cell lines that produced monoclonal antibodies against cholera enterotoxin (CT) were isolated and characterized. All of the monoclonal antibodies contained the kappa light chain; 14 were of the immunoglobulin G1 (IgG1) isotype and 3 were IgG2a. The 17 monoclonal antibodies were divided into a minimum of seven different specificity groups based on their abilities to bind to the following purified test antigens in solid-phase radioimmunoassays: CT, the A and B polypeptides of CT (CT-A and CT-B, respectively), and the heat-labile enterotoxins designated LTh and LTp from Escherichia coli. The binding of these antibodies to the following subunits and fragments of CT was also determined in Western blots: pentameric CT-B, monomeric CT-B, intact CT-A, and the A1 fragment of CT-A. Each of the monoclonal antibodies was tested for neutralization of CT and for precipitation with CT in immunodiffusion tests. Antigenic determinants were identified on CT that were not present either on CT-A or CT-B. One class was unique for CT and another was shared with LTh and LTp. Antibodies directed against these holotoxin-specific determinants had no neutralizing activity. Most of the monoclonal antibodies that reacted strongly with CT-A or CT-B also reacted strongly with CT holotoxin; however, one class of antibody reacted strongly with CT-A but weakly with CT. Among the monoclonal antibodies against CT-A or CT-B, some were specific for CT and others cross-reacted with LTh and LTp or with LTh only. The most potent neutralizing antibodies were against CT-B, and all of our monoclonal antibodies against CT-B had some neutralizing activity. In contrast, only some of the monoclonal antibodies against CT-A had neutralizing activity, and their specific activities were low. We found no direct correlation between the ability of monoclonal antibodies to neutralize CT and to cross-react with LTh or LTp. None of the epitopes recognized by our monoclonal anti-CT antibodies was present on CT-A and CT-B.
Effect of ibuprofen on fever and metabolic changes induced by continuous infusion of leukocytic pyrogen (interleukin 1) or endotoxin
Authors: Sobrado J , Moldawer L L , Bistrian B R , Dinarello C A , Blackburn G L
Published: January 2020

Many of the metabolic sequelae to infection and inflammation, such as fever, trace mineral redistribution, skeletal muscle catabolism, and the acute-phase protein response, are mediated by leukocytic pyrogen (interleukin 1). In the anterior hypothalamus and in skeletal muscles leukocytic pyrogen appears to induce the synthesis of prostaglandin E2 which mediates fever and skeletal protein catabolism. It is unclear whether any additional metabolic responses to leukocytic pyrogen result from prostaglandin production. This study was undertaken to investigate the ability of ibuprofen, a specific cyclooxygenase inhibitor, to alter protein and trace metal responses to leukocytic pyrogen or endotoxin when given in quantities sufficient to block the febrile response. In guinea pigs given continuous infusions of leukocytic pyrogen or endotoxin, a 0.6 to 0.8 degrees C fever was observed within 4 h, and zinc and iron concentrations in serum fell by 63 to 78% (P less than 0.01). Rates of whole body amino acid appearance, oxidation, and incorporation into protein were all significantly increased by leukocytic pyrogen and endotoxin treatment, (P less than 0.05) as were the fractional hepatic and seromucoid protein synthesis rates in leukocytic pyrogen-treated animals (P less than 0.01). Muscle protein synthesis was unchanged. Although pretreatment with infusions of ibuprofen completely ablated the febrile response to leukocytic pyrogen and endotoxin, decreases in zinc and iron concentrations in serum and leukocytosis were unaffected. Overall increases in whole body amino acid kinetics induced by leukocytic pyrogen or endotoxin were only minimally affected by ibuprofen. We concluded that treatment with prostaglandin synthesis inhibitor ibuprofen did not affect whole body trace metal, hematological, or hepatic acute-phase-induced responses to leukocytic pyrogen or endotoxin, either because these responses are prostanoid independent or because they are only partially mediated by eicosanoid products.
Susceptibility of inbred mice to rickettsiae of the spotted fever group
Authors: Eisemann C S , Nypaver M J , Osterman J V
Published: January 2020

A mouse strain susceptible to lethal infection with Rickettsia conorii was required for testing vaccine efficacy and for studying the immunology and pathogenesis of infection. Among 20 strains of inbred mice inoculated intraperitoneally with the Malish strain of R. conorii, the C3H/HeJ mouse strain was the most susceptible, with a 50% lethal dose of approximately 10 PFU. Infection of all mouse strains resulted in a measurable antibody response; the highest titers correlated with the greatest degree of rickettsial replication as measured by plaque assay of infected spleen homogenates. Inoculation of C3H/HeJ mice with 5.0 log10 organisms of strain Malish by the subcutaneous route did not result in lethal infection. The Casablanca and Moroccan strains of R. conorii were not lethal for C3H/HeJ mice and, in addition, produced plaques in L-929 cells morphologically distinct from those produced by the Malish strain. The only other spotted fever group rickettsia tested which produced a lethal infection in C3H/HeJ mice was Rickettsia sibirica. Sublethal infection with any of the spotted fever rickettsiae tested protected against lethal infection with R. conorii. These data established a lethal challenge system for examining the protective efficacy of spotted fever immunogens and presented evidence of biological variation among strains of R. conorii.
Temperature-dependent expression of virulence genes in Shigella species
Authors: Maurelli A T , Blackmon B , Curtiss R
Published: January 2020

The pathogenicity of Shigella spp. involves the ability of the bacteria to penetrate and replicate within the epithelial cells of the large intestine. Model systems for examining the virulence of shigellae employ Henle intestinal epithelial cells in tissue culture and an in vivo assay for virulence in guinea pig eyes (Sereny test). Using these systems, we studied the genetic and physiological bases for the ability of shigellae to invade epithelial cells. We found that expression of virulence in Shigella spp. is dependent on the temperature at which the bacteria are grown. When grown at 37 degrees C, strains of Shigella flexneri 2a, Shigella sonnei, and Shigella dysenteriae 1 were fully virulent and invaded Henle cells. They also produced keratoconjunctivitis in guinea pigs. When grown at 30 degrees C, the bacteria neither penetrated Henle cells nor produced conjunctivitis in the Sereny test and were phenotypically avirulent. Strains grown at 33 degrees C were only partially invasive in the Henle assay, whereas strains grown at 35 degrees C were as invasive as strains grown at 37 degrees C. Using the Henle cell assay, we determined that the loss of ability to penetrate epithelial cells was completely reversed by shifting the growth temperature from 30 to 37 degrees C. The percentage of Henle cells invaded by bacteria increased with increasing time of growth at 37 degrees C. Restoration of invasiveness after growth at 30 degrees C required protein synthesis. When shigellae were grown at 30 degrees C and shifted to 37 degrees C for 2 h in the presence of chloramphenicol, the bacteria remained noninvasive. Similarly treated bacteria grown at 37 degrees C were still invasive. These results suggested that expression of one or more genes required for virulence of Shigella spp. are subject to regulation by growth temperature.
Correlation of elastase production by some strains of Aspergillus fumigatus with ability to cause pulmonary invasive aspergillosis in mice
Authors: Kothary M H , Chase T , Macmillan J D
Published: January 2020

Seventy-five strains of Aspergillus fumigatus were screened for production of elastase in liquid and agar media containing elastin in yeast carbon base buffered with 0.05 M borate, pH 7.6. Of 71 strains which cleared elastin in agar plates, 33 produced elastase in liquid medium, as measured spectrophotometrically with elastin-Congo red. Six strains producing elastase and four nonproducers were tested for ability to cause invasive aspergillosis in immunocompromised mice (six mice per strain). All 36 mice exposed to elastase-producing strains died within 48 to 96 h. Lung tissue from dead mice showed hyphae and necrosis of the alveoli. Lungs of mice exposed to spores of strains not producing elastase showed few germinated spores and no destruction of alveoli. These results indicate that elastase may be significant in the invasion process.
Characteristics of Rickettsia mooseri infection of normal and immune mice
Authors: Crist A E , Wisseman C L , Murphy J R
Published: January 2020

Rickettsia mooseri infection initiated by subcutaneous injection has been studied in BALB/c mice with the objective of developing a model for the study of immune mechanisms. Characterization of infection included the following: measurement of the replication, dissemination, and clearance of rickettsiae; measurement of correlates of the immune response, including humoral antibody, hypersensitivity to subcutaneously inoculated rickettsial antigen, and activation of nonspecific macrophage microbicidal capacity; and measurement of resistance to a second homologous challenge. Local infection at the site of subcutaneous injection progressed through day 5 and was controlled by day 7. Systemic infection as determined by the presence of rickettsiae in spleen was first detected on day 7 and progressed through day 14; however, rickettsiae persisted in this organ at reduced numbers through at least day 28. Control of the local infection at the site of subcutaneous injection occurred at about the time humoral antibodies and hypersensitivity reactions to subcutaneously injected rickettsial antigens became demonstrable and was paralleled by a capacity to resist homologous subcutaneous challenge at a site distant from that of the primary infection. Systemic infection progressed in spite of this acquired immune capacity and was controlled in the spleen in parallel with the development of enhanced macrophage microbicidal capacity in the liver. The results show that an acquired immunity is capable of restricting rickettsial growth at subcutaneous sites at a time when rickettsiae are increasing in titer in deep organs.
Antibodies to laminin in American cutaneous leishmaniasis
Authors: Avila J L , Rojas M , Rieber M
Published: January 2020

We found that serum samples from patients with different clinical forms of American cutaneous leishmaniasis (ACL) contained immunoglobulin G and immunoglobulin M antibodies which reacted with laminin but not with various other purified connective tissue components, such as collagen types I, III, IV, and V and fibronectin. Eighty-one percent of ACL patients had high antilaminin antibody levels, with a relationship existing between ACL ulcers and antibody levels. This was not, however, the case with patients having treated and healed ACL ulcers; only 34% of these patients had elevated antilaminin antibodies. Eighty-four percent of chronic Chagas' disease patients were also found to contain antilaminin antibodies that were limited to the immunoglobulin G class, but these were not detected in patients suffering from any of 11 other infectious diseases.
Respiratory syncytial virus infection in mice
Authors: Taylor G , Stott E J , Hughes M , Collins A P
Published: January 2020

The A2 strain of human respiratory syncytial virus replicated in the nose and lung of BALB/c mice, with virus growing to higher titers in older animals than in younger animals. Virus was recovered from the nose between days 2 and 7 with peak titers on days 3 and 4, and from the lungs between days 2 and 9, with peak titers on days 4 through 6. Serum antibody developed 2 weeks after infection. Viral antigen was demonstrated in the alveolar cells of the lung by immunofluorescence. Histopathological changes included infiltration by mononuclear cells of the peribronchiolar and perivascular tissue, some interstitial thickening, and formation of multinucleated giant cells. Virus could not be recovered from the respiratory tract of mice inoculated with bovine strains of respiratory syncytial virus. Growth of the A2 strain of human respiratory syncytial virus in different cell lines affected its infectivity for mice. Infection of BALB/c mice with respiratory syncytial virus provides a highly reproducible model for the study of the pathogenesis of and mechanisms of immunity to this virus.
Killing of human malaria parasites by macrophage secretory products
Authors: Wozencraft A O , Dockrell H M , Taverne J , Targett G A , Playfair J H
Published: January 2020

The susceptibility of the human malaria parasite, Plasmodium falciparum, to killing in vitro by macrophage secretory products was investigated. The effect of O2 radicals and tumor necrosis factor on parasite viability was assessed both morphologically and by following the uptake of [3H]hypoxanthine. H2O2 produced by the interaction of glucose and glucose oxidase was found to reduce viability; this effect was reversed by the addition of exogenous catalase. Further studies indicated that the catalase level within the erythrocyte was not altered upon parasite invasion. O2 radicals produced during the xanthine-xanthine oxidase interaction also killed P. falciparum. The addition of various O2 radical scavengers (including catalase) did not reverse this effect; therefore, it was not possible to determine which of the O2 radicals were involved in the killing process. Samples from three different sources containing tumor necrosis factor, a nonspecific soluble mediator derived from Mycobacterium bovis BCG-activated macrophages treated with endotoxin, also killed the parasite. There was no evidence that tumor necrosis factor or the products of the xanthine-xanthine oxidase interaction caused damage to the erythrocyte membrane that could be implicated as an important aspect of the killing process. These findings all strongly suggest that such macrophage products play an important role in immunity to malaria.
Coccidiosis: rapid depletion of circulating lymphocytes after challenge of immune chickens with parasite antigens
Authors: Rose M E , Hesketh P , Rennie M
Published: January 2020

Characteristic changes in the numbers of peripheral blood leukocytes occurred after specific challenge of chickens immunized by infection with the intracellular intestinal coccidian parasite Eimeria maxima. Within minutes of enteric or intravenous challenge with viable parasites or with soluble parasite antigen, the numbers of circulating lymphocytes and, to a lesser extent, of heterophils were reduced. This was followed by a period of leukocytosis, the main cellular constituents of which were heterophils and lymphocytes. Indirect fluorescent staining with antisera to T- or B-lymphocytes showed the depletion in lymphocytes to be accounted for mainly by a reduction in the number of T-cells. The leukopenia after oral challenge, found in immunized birds, could be transferred to normal birds by the intravenous injection of serum, plasma, extracts of leukocytes, or suspensions of viable spleen cells.
Intracellular growth of Legionella pneumophila within Acanthamoeba castellanii Neff
Authors: Holden E P , Winkler H H , Wood D O , Leinbach E D
Published: January 2020

Acanthamoeba castellanii Neff supports the intracellular growth of Legionella pneumophila. When acanthamoebae were exposed to L. pneumophila for 1 h and then washed free of unassociated bacteria and placed in liquid culture, levels of viable amoeba-associated legionellae and legionellae free in the culture medium increased by three to four orders of magnitude in 48 to 72 h. However, most of the legionellae remained amoeba-associated and could be cultured only after disruption of the amoebae. Furthermore, legionella viability declined rapidly in amoeba culture medium alone or when bacteria and amoebae were separated by a microporous membrane. Therefore, direct amoeba-legionella contact is required for this growth. Infected acanthamoebae treated with cold acetone to permeabilize them to fluorescent-labeled anti-L. pneumophila antibody appeared to contain far more legionellae than amoebae fixed with glutaraldehyde so as to prevent antibody penetration. Electron micrographs of infected A. castellanii showed numerous bacteria, including some dividing forms, within vacuoles in the cytoplasm. These results together show that A. castellanii is able to provide an intracellular niche for the growth of L. pneumophila.
Variation in a major surface protein of Lyme disease spirochetes
Authors: Barbour A G , Tessier S L , Hayes S F
Published: January 2020

Two monoclonal antibodies (H6831 and H5TS) differed in their indirect immunofluorescence reactivity when tested against 14 strains of Lyme disease spirochetes. Strains were bound by both antibodies, by H6831 or H5TS alone, or by neither. Western blot and immunoprecipitation studies revealed that the determinants of both antibodies were associated with abundant proteins with apparent subunit molecular weights of ca. 34,000 (34K-range proteins). The following results indicated that the 34K-range proteins were exposed on the surface of the spirochetes. (i) Antibody H6831 agglutinated the spirochetes; (ii) immune electron microscopy showed that the H6831 determinant was associated with the outer membrane; (iii) radiolabeled H6831 bound to live organisms; and (iv) proteases effectively removed the 34K-range proteins from intact cells. With their demonstrated variability and exposure on the surface, the 34K-range proteins may contribute to the serotype specificity of Lyme disease spirochetes.
Role of heme compounds and haptoglobin in Vibrio vulnificus pathogenicity
Authors: Helms S D , Oliver J D , Travis J C
Published: January 2020

An induced peritonitis model was employed in mice to determine whether heme-containing molecules enhance the lethality of infections by Vibrio vulnificus. The lethality of intraperitoneal (ip) inocula of the bacteria was increased by concurrent injections (ip) of hemoglobin, methemoglobin, or hematin, but not by myoglobin. Similar results were obtained in mice with phenylhydrazine-induced hemoglobinemia, in which after ip injections of V. vulnificus, a direct correlation between lethality and levels of plasma hemoglobin was observed. In vitro studies indicated that the growth of V. vulnificus, which was limited in an iron-poor medium, was enhanced by the addition of hemoglobin in a manner similar to an inorganic iron source, ferric ammonium citrate. These results suggest that V. vulnificus is capable of extracting iron from hemoglobin for use as a nutrilite, thereby promoting growth and increased lethality in the in vivo models. Further studies with human serum cultures demonstrated that the growth of V. vulnificus was not decreased when hemoglobin added to the serum was completely complexed with haptoglobin; these results are in opposition to those with cultures of Escherichia coli. These results are discussed relative to the capacity of V. vulnificus to produce fatal human infections.