bluuebunny/crossref_metadata_2025 huggingface dataset:
Infectious agents in immunodeficient murine models: pathogenicity of Actinomyces israelii serotype I in congenitally athymic (nude) mice
Authors: Beaman B L , Gershwin M E , Maslan S
Published: January 2020

Nude (Nu/Nu) and heterozygous (NU/+) mice were infected with Actinomyces israelii serotype I by either intranasal instillation or intravenous injection. Lung clearance data and 50% lethal dose values indicated that T-lymphocytes were not necessary for pulmonary clearance or prevention of systemic actinomycosis. However, T-lymphocyte deficiency may play a role in the localized cervicofacial form of actinomycosis.
Microtechnique for studies on the role of monocytes in the stimulation of lymphocytes
Authors: Tärnvik A
Published: January 2020

A microtiter technique was used to measure lymphocyte stimulation by antigen-pulsed monocytes. Monocytes from human blood were isolated on polyester film disks. The disks were exposed to antigen and incubated together with lymphocytes in the wells of a microtiter plate. The method was technically simple and required no expensive materials.
Properties of extracellular neuraminidase produced by group A streptococcus
Authors: Davis L , Baig M M , Ayoub E M
Published: January 2020

Extracellular neuraminidase production by group A streptococci was examined in 92 strains. Fourteen of these strains produced appreciable amounts of enzyme; 12 of the neuraminidase-producing strains belonged to T types 1, 4, and 12. Production of the enzyme paralleled bacterial growth in culture and was maximal in medium containing 0.2% glucose. The enzyme produced by one of these strains was partially purified by ammonium sulfate fractionation and filtration on G-200 Sephadex. Its molecular weight was estimated at 90,000. Activity was optimal at pH 5.7 and in the presence of 0.01 to 0.03 M calcium and magnesium cations. The enzyme was stable at temperatures of 4 and 37 degrees C for at least 24 h but was inactivated within 10 min at temperatures of 50 and 65 degrees C. The enzyme hydrolyzed 40% of the sialic acid in bovine submaxillary mucin, but was inactive on sialyl-lactose, porcine submaxillary mucin, oligosaccharides derived from porcine mucin, or human orosomucoid. The Km value for this enzyme with bovine submaxillary mucin as substrate was in the order of 3.6 x 10(-4) M.
Heat-labile enterotoxin production in isolates from a shipboard outbreak of human diarrheal illness
Authors: Wachsmuth K , Wells J , Shipley P , Ryder R
Published: January 2020

As reported elsewhere, an enterotoxigenic strain of Escherichia coli serotype O25:K98:NM was epidemiologically incriminated as the etiological agent in a shipboard outbreak of diarrheal illness. This enterotoxigenic E. coli strain and possibly other enteric isolates were found to produce heat-labile toxin and not heat-stable toxin. Since previous genetic analyses of enterotoxigenic E. coli strains producing heat-labile and heat-stable toxins have shown a plasmid location for both toxin determinants and since in this outbreak more than one bacterial strain appeared to produce only heat-labile toxin, the possibility of an extrachromosomal heat-labile toxin determinant was investigated. Results of endonuclease cleavage and hybridization experiments, as well as apparent heat-labile toxin phenotypic instability, strongly suggest a plasmid mediation of toxin production. Additionally, the stability of this heat-labile toxin production was evaluated after several traditional methods of bacterial cell preservation.
Correlation between genetic regulation of antibody responsiveness and protective immunity induced by Plasmodium berghei vaccination
Authors: Heumann A M , Stiffel C , Monjour L , Bucci A , Biozzi G
Published: January 2020

High (H) and low (L) antibody responder lines of mice were produced by two independent bidirectional selective breedings for quantitative antibody responsiveness to heterologous erythrocytes (selection I and selection II). In both selections the antibody response to P. berghei antigens was 8- to 10-fold higher in H than in L lines. The character "high response" presents an incomplete dominance o- 18% in selection I and 67% in selection II. In selection II the variance analysis indicates that at least three independent loci intervene in the regulation of responsiveness to P. berghei antigens. The innate resistance and the protective efficacy of vaccination against P. berghei infection induced by parasitized erythrocytes was measured in H and L lines and in the interline hybrids F1, BcH, and BcL of selections I and II. No very significant difference was observed in the innate resistance to P. berghei infection between H and L mice of both selections. Vaccination induced a very efficient protection in the two H lines (94 and 95% survival), whereas only a weak protection was induced in the two L lines (16 and 31% survival); the degree of protection is intermediate in interline hybrids F1, BcH, and BcL. In both selections a good linear correlation was demonstrated between the level of vaccination-induced antibody and the degree of resistance measured as percentage of survival. The present results indicate that the vaccination-induced P. berghei immunity is essentially due to the antibody response, whereas the bactericidal activity of macrophages and the cell-mediated immunity do not play a determinant role.
Chlorpromazine Reverses Diarrhea in Piglets Caused by Enterotoxigenic
Escherichia coli
Authors: Lönnroth Ivar , Andrén Birgitta , Lange Stefan , Martinsson Kjell , Holmgren Jan
Published: January 2020

The effect of chlorpromazine (CPZ) on diarrhea caused by enterotoxigenic
Escherichia coli
was tested in piglets since CPZ has been shown to be a potent antagonist to enterotoxins in vitro in a cell system and in vivo in a mouse model. Experimental diarrhea was induced in three litters of newborn piglets which were infected by mouth with 2 × 10
9
E. coli
bacteria, which produce heat-labile (LT) and heat-stable (ST) enterotoxins. Treatment with CPZ given intramuscularly 1 h after the onset of diarrhea reversed fluid secretion in small intestine as well as dehydration, as judged by clinical criteria. A dose of 5 mg of CPZ per kg of body weight completely normalized the intestinal-fluid content measured 4 h after diarrhea developed, whereas 1 to 2 mg of CPZ per kg of body weight was somewhat less effective but still caused significant reduction of fluid (
P
< 0.001). Studies with radioactive [
35
S]CPZ showed preferential and dose-dependent uptake of
35
S in the intestinal mucosa, the radioactivity being evenly distributed in the membranes of both crypt and villus cells. The enzyme adenylate cyclase, which probably mediates the cellular effects of LT, was shown to have two- to threefold higher activity in the infected than in the uninfected animals. This activation was reduced about 50% by the CPZ treatment (2 mg/kg of body weight). In a preliminary field trial the effect of CPZ was tested in a spontaneous outbreak of diarrhea in piglets due to enterotoxinogenic
E. coli.
The animals were treated either with oral electrolyte solution and standard antimicrobial agents only (controls) or with 1 mg of CPZ per kg of body weight intramuscularly in addition to this treatment. The mean duration of diarrhea in CPZ-treated animals was significantly shorter, 4.1 h (
n
= 23), than that in controls, 7.2 h (
P
< 0.05).
Antibody to Rickettsia mooseri erythrocyte-sensitizing substance
Authors: Murphy J R , Fiset P , Snyder L B , Wisseman C L
Published: January 2020

Erythrocyte-sensitizing antigens from Rickettsia mooseri (R. typhi) were found to bind to rabbit erythrocytes. Upon reintroduction into the donor, such antigen-sensitized cells caused the production of antibodies of restricted serological reactivity.
Interaction of Mycoplasma pneumoniae with alveolar macrophages: viability of adherent and ingested mycoplasmas
Authors: Erb P , Bredt W
Published: January 2020

Guinea pig peritoneal or alveolar macrophages were inoculated with Mycoplasma pneumoniae cells. Extracellular mycoplasms were killed by complement treatment, and the effect of macrophage action on the number of the remaining viable mycoplasmas was observed. The complement killing was to some extent inhibited by the presence of the macrophages, but the mechanism of this protection remains unknown. Opsonized mycoplasmas were ingested, and approximately 98% were killed within 4 h. The killing rate was somewhat lower than comparable data for bacteria, but lack of cell wall and high lipid content of the membrane apparently do not cause a significant delay in intracellular destruction.
Inability of immune cells treated with anti-thymocyte serum to confer on hamsters resistance to cutaneous infection with Treponema pertenue
Authors: Chan J K , Schell R F , LeFrock J L
Published: January 2020

The mechanism by which hamsters acquire resistance to yaws or frambesia is poorly understood. This investigation has shown that immune lymphoid cells (spleen and lymph node) could confer on hamsters resistance to infection with Treponema pertenue. Treatment of these immune cells with a specific antithymocyte serum (ATS) inhibited the transfer of resistance. Twenty-one days after infection, recipients of immune cells treated with ATS had cutaneous lesions, in contrast to recipients of immune cells treated with normal rabbit serum. Treatment of immune cells with ATS, however, did not completely abolish resistance to treponemal infection. The weight and number of treponemes in the lymph nodes of recipients were significantly lower than those infused with normal cells treated with ATS or normal rabbit serum. The specificity of the ATS was demonstrated by its failure to inhibit functional antibody-producing cells and its high cytotoxic activity for thymocytes. These results present direct evidence that ATS-sensitive cells are involved in resistance to frambesial infection.
Immune responses to Schistosoma mansoni in rhesus monkeys with multiple chronic and early primary infections
Authors: Maddison S E , Slemenda S B , Hillyer G V , Chandler F W , Kagan I G
Published: January 2020

Immunological reactivity in 10 rhesus monkeys was monitored over a 22-week period. Cellular and humoral responses of three animals were studied after primary infection with Schistosoma mansoni. Two uninfected animals served as controls. Increased lymphocyte proliferative responsiveness to mitogens and adult worm antigen was evident during the prepatent period of the infection. Marked suppression of these responses occurred during the acute phase of the disease, but by weeks 9 and 11 the animals were again responsive to mitogens and antigen, respectively, and remained so throughout the remainder of the observation period. No antibody response to various cercarial, adult worm, and egg antigens could be detected until weeks 5 to 7, after which these responses also persisted. Comparison of the immunological reactivities of these animals with primary infection and those of five chronically infected immune animals indicated possible correlations between protective immunity and (i) strong Cercarienhüllenreaktion reactivity, and (ii) lymphocyte proliferative responsiveness to adult worm antigen.
Intestinal and serum antibody responses in mice after oral immunization with Salmonella, Escherichia coli, and Salmonella-Escherichia coli hybrid strains
Authors: Hohmann A , Schmidt G , Rowley D
Published: January 2020

After oral feeding of mice with avirulent Salmonella, Escherichia coli, or hybrid strains, only certain bacterial strains were able to multiply and persist within the small intestinal Peyer's patches. After oral vaccination alone, or oral priming and subsequent parenteral boosting, antibody class and titers were detected, using a radioimmunoassay on serum and intestinal fluid or a plaque-forming cell assay on spleens. Only those strains that persisted in the Peyer's patches stimulated the production of serum and intestinal immunoglobulin A antibodies against their respective O antigens. Nonpersistent strains were weakly immunogenic, and antibodies, when present, were largely non-immunoglobulin A and confined to the serum.
Efficacy of antimicrobial therapy in experimental rat pneumonia: antibiotic treatment schedules in rats with impaired phagocytosis
Authors: Bakker-Woudenberg I A , van Gerwen A L , Michel M F
Published: January 2020

Pneumococcal pneumonia in rats with intact host defense mechanisms could be successfully cured by penicillin. The efficacy of this antibiotic therapy was lost in cobra venom factor-treated rats which had selectively impaired phagocytic functions. In these animals the effect of penicillin therapy was improved by increasing the daily dose and the frequency of injections and by earlier initiation of the therapy. The efficacy of penicillin in the cobra venom facttor-treated rats was restored either by markedly increasing the daily dose of penicillin or by increasing the daily dose in combination with a reduced interval of the penicillin injections.
Experimental gram-negative bacterial sepsis: prevention of mortality not preventable by antibiotics alone
Authors: Greisman S E , DuBuy J B , Woodward C L
Published: January 2020

Outbred Swiss mice were inoculated intraperitoneally or intravenously with one 90 to 100% lethal dose of Escherichia coli O:18, Proteus mirabilis, or Klebsiella pneumoniae. After carefully timed intervals, aminoglycoside antibiotics were begun at dosages nnd intervals predetermined to constitute optimal therapy. With progressive increases in delay of antibiotic therapy, mortality rates increased progressively from 0% to 90 to 100%. Standardized models of infection were developed by selecting delay periods before initiating antibiotic therapy such that 50 to 70% mortalities resulted. Utilizing these models, agents with reputed anti-endotoxin activity were administered concomitantly with the delayed antibiotic therapy to determine if any could prevent gram-negative septic mortality no longer preventable by the antibiotics alone. The following were observed: (i) adrenal corticosteroids prevented mortality that was no longer preventable by optimal aminoglycoside antibiotics alone. The following were preventable by optimal aminoglycoside antibiotic therapy alone; (ii) specific antisera also did so, provided anaphylaxis was circumvented; (iii) in one model (P. mirabilis), such protection by adrenal corticosteroids and specific antiserum could be additive; (iv) adrenal corticosteroids and specific antiserum acted synergistically with the aminoglycoside antibiotics--no protection was achieved by delayed administration of the steroids or antiserum alone; (v) timing was crucial--the synergistic protective activity of adrenal corticosteroids and of specific antiserum with aminoglycosides declined rapidly as infection progressed; (vi) cyclophosphamide pretreatment markedly impaired the synergistic protective activity of specific antiserum and of adrenal corticosteroids with aminoglycosides; (vii) no reputed anti-endotoxin agents other than adrenal corticosteroids and specific antiserum proved capable of preventing mortality not preventable by aminoglycoside antibiotics alone. These included antisera to rough mutant Enterobacteriaceae of Rc, Rd, and Re chemotypes, anticoagulants (heparin), ascorbic acid, antiproteolytic agents (aprotinin), alpha adrenergic blockers (phenoxybenzamine), prostaglandin synthetase inhibitors (acetylsalicylic acid, sodium salicylate, indomethacin), nicotinamide, glucose, and insulin-glucose-potassium mixtures.
Depression of bovine monocyte chemotactic responses by bovine viral diarrhea virus
Authors: Ketelsen A T , Johnson D W , Muscoplat C C
Published: January 2020

Incubation of bovine peripheral blood monocytes with bovine viral diarrhea virus (either Singer or NY-1 strain) caused a consistent, statistically significant decrease in their random locomotion (no chemoattractant) and chemotaxis towards a chemotactic lymphokine. Chemotaxis was determined by a modification of the Boyden method. Incubation of bovine viral diarrhea virus with mononuclear cells depressed chemotaxis by a mean of 56% (P less than 0.0005). Heat-killed virus had no effect on monocyte motility. Data suggest that bovine viral diarrhea virus can rapidly suppress monocyte functions in vitro, but by unknown mechanisms, not by killing cells.
Role of Escherichia coli K capsular antigens during complement activation, C3 fixation, and opsonization
Authors: Van Dijk W C , Verbrugh H A , van der Tol M E , Peters R , Verhoef J
Published: January 2020

Escherichia coli strains with K capsular polysaccharides are relatively resistant to phagocytosis by polymorphonuclear leukocytes, in contrast to E. coli strains without K antigens. This inhibition of phagocytosis is related to an impaired recognition of the K+ strains by the phagocytes due to ineffective opsonization. All five strains without K antigens were readily phagocytized after opsonization in 5% normal serum, compared with no uptake of the K+ strains. Evidence is presented that the decreased opsonization of the K+ strains in normal serum is caused by a low rate of complement activation of the strains, with subsequent absence of C3b fixation or C3d fixation or both to the cell wall of the bacteria. After removal of the K+ antigens by heating of a K+ E. coli strain, the strain was able to activate complement, to bind C3b or C3d or both, and to become opsonized. Complement was then activated via the classical and alternative pathways, which was comparable to the complement consumption by K- E. coli.
Systemic and gastrointestinal candidiasis of infant mice after intragastric challenge
Authors: Pope L M , Cole G T , Guentzel M N , Berry L J
Published: January 2020

Systemic and gastrointestinal infection can be established in infant mice after intragastric challenge with Candida albicans. Differences in virulence of the six strains tested were noted. As early as 3 h after infection, some but not all livers, spleens, and kidneys contained C. albicans, but the peak number of colony-forming units in these organs was seen at 6 h. The early colonization of the organs could not be attributed to aspiration of the inoculum since about 90% of lungs and livers tested yielded no colony-forming units at 10 to 15 min postinfection. In animals with systemic infections, lungs, livers, kidneys, and spleens showed similar numbers of colony-forming units within the organs during the first 6 h postinfection- and then the number declined progressively up to 72 h. The gastrointestinal tract was colonized throughout a 20-day period of study. Counts made at intervals beyond day 1 yielded between 10(5) and 10(6) colony-forming units in the stomach, ileum, and cecum. Preparatory techniques for scanning electron microscopy preserved the yeast, intestinal mucus layer, and epithelial surface and made it possible to visualize the association between the pathogen and host tissues within the digestive tract.
Evidence for pili-mediated adherence of Klebsiella pneumoniae to rat bladder epithelial cells in vitro
Authors: Fader R C , Avots-Avotins A E , Davis C P
Published: January 2020

The possible role of pili in the pathogenesis of urinary tract infections caused by Klebsiella pneumoniae was studied in an in vitro mixture of a phosphate-buffered saline suspension of rat bladder epithelial cells and phosphate-buffered saline-washed K. pneumoniae. Nonpiliated and piliated populations derived from a single K. pneumoniae strain were obtained by controlling the total time of growth in broth medium. The piliated phase demonstrated a significant increase in adherence when compared to the nonpiliated phase. Incubation of the bacteria and epithelial cell mixture at 4 and 37 degrees C resulted in no differences in adherence; optimal adherence occurred at pH 5. Pretreatment of the bacteria with enzymes to destroy the pili resulted in a decrease in adherence, as did killing the bacteria by various means before adherence testing. Pretreatment of the epithelial cells with certain saccharides inhibited bacterial adherence. Finally, a 96% decrease in adherence was observed after coincubation of bacteria and epithelial cells with papain-treated antipili antibodies. Thus, it appears that pili on the surface of K. pneumoniae mediate attachment of the bacteria to rat bladder epithelial cells.
Genetics of staphylococcal enterotoxin B in methicillin-resistant isolates of Staphylococcus aureus
Authors: Shafer W M , Iandolo J J
Published: January 2020

Biophysical and genetic analysis of staphylococcal enterotoxin B (SEB) synthesis in 16 methicillin-resistant (Mecr) Staphylococcus aureus isolates demonstrated that the toxin gene (entB) can occupy either a plasmid or chromosomal locus. Biophysical analysis of the plasmid deoxyribonucleic acid content of these strains by agarose gel electrophoresis revealed the presence of a 1.15-megadalton plasmid in six isolates that appears to contain the entB gene. Genetic manipulation of SEB synthesis by transduction and elimination procedures demonstrated that this plasmid is critical for enterotoxigenesis. Nevertheless, the majority of the Mecr SEB+ isolates (62.5%) analyzed in this investigation were found to lack the 1.15-megadalton plasmid. In at least two of these strains (COL and 57-dk), transduction and elimination procedures showed that entB was chromosomal. Genetic studies involving strains harboring either a plasmid or chromosomal entB gene demonstrated that toxin synthesis was coeliminated with mec. However, analysis of the entB and mec loci by transformation or transduction showed that the genes are not closely linked. On the other hand, transduction of entB, regardless of the donor, was observed when both mec and the Tcr plasmid were jointly cotransduced. This finding suggests that, during transduction, a transient association between entB, mec, and the Tcr plasmid may exist.
Wheat germ agglutinin blockage of chlamydial attachment sites: antagonism by N-acetyl-D-glucosamine
Authors: Levy N J
Published: January 2020

Addition of 2 to 10 micrograms of wheat germ agglutinin (WGA), a lectin from Triticum vulgaris specific for N-acetyl-D-glucosamine, per ml to suspensions of mouse fibroblasts (L cells) blocked the attachment of 14C-labeled Chlamydia psittaci 6BC to the L-cell surface. WGA and strain 6BC competed for similar sites on L cells, but once bound, one was not replaced by the other. N-Acetyl-D-glucosamine, but not other monosaccharides of related structure, antagonized the blocking action of WGA. Lectins with specificities other than that of WGA prevented chlamydial attachment only at much higher concentrations or not at all. Exposure of L cells to trypsin and to high multiplicities of strain 6BC decreased the amount of subsequently added 3H-labeled WGA that was bound by these cells. WGA also blocked the attachment of strain 6BC to other established cell lines of murine, simian, and human origin. A lymphogranuloma venereum strain (440L) of C. trachomatis was just as sensitive to the blocking action of WGA as was strain 6BC. It appears that the attachment of both C. psittaci and C. trachomatis to host cells of diverse origin involves an N-acetyl-D-glucosamine-containing entity that binds WGA with high affinity.
Immunochemical cross-reactions between type III group B Streptococcus and type 14 Streptococcus pneumoniae
Authors: Crumrine M H , Fischer G W , Balk M W
Published: January 2020

Serological cross-reactions between certain streptococci and some serotypes of Streptococcus pneumoniae have been reported. These studies detail the serological cross-reactivity observed between hot HCl-extracted group b streptococcus type III (GBS III) antigens and S. pneumoniae type 14 (Pn 14) polysaccharide. Similar electrophoretic migration patterns of GBS III and Pn 14 were observed when either type-specific BGS III antisera or pneumococcal omniserum was utilized to precipitate these antigens. Both the GBS III antigen and the Pn 14 polysaccharide migrated toward the cathode, whereas all other pneumococcal polysaccharides migrated toward the anode. No cross-reactions were observed between GBS III antisera and the 11 other types of pneumococcal polysaccharides. Lines of identity were observed between type-specific GBS III antisera and monospecific Pn 14 antiserum with either GBS III antigens or purified Pn 14 polysaccharide. The cross-reacting antigens of GBS III and Pn 14 appear to be identical by immunodiffusion and immunoelectrophoresis.
Macrophage Dysfunction After Burn Injury
Authors: Loose Leland D. , Turinsky Jiri
Published: January 2020

The phagocytic and microbicidal activities of alveolar and peritoneal macrophages were evaluated 4 and 24 h after a full-thickness scald burn of 26 to 28% body surface area in anesthetized rats. The contribution of serum factors to the macrophage functions was studied concurrently. The phagocytic activity of alveolar macrophages obtained 4 or 24 postburn was reduced approximately 65% below control values when they were incubated in media containing autologous serum and approximately 45% (below controls) when they were incubated in media containing normal (control) serum. A similar, although not as marked, decrease in the phagocytic activity of peritoneal macrophages was also demonstrated. Serum obtained from rats 4 or 24 h postburn had a significant suppressive effect on the phagocytic activity of control alveolar, but not peritoneal, macrophages. The intracellular microbicidal activity of peritoneal macrophages obtained at the postburn intervals and incubated in media containing either autologous or control serum was unaltered from control values. However, alveolar macrophages obtained 24 h, but not 4 h, postburn had a significant (approximately 80%) increase, above control values, in their microbicidal activity. Serum obtained 24 h, but not 4 h, postburn stimulated control alveolar macrophage killing ability. These data indicate that thermal injury induces a defect in the phagocytic activity rather than the microbicidal activity of macrophages. This phagocytic alteration is mediated, in part, by serum.
Complement activation in acne vulgaris: consumption of complement by comedones
Authors: Webster G F , Leyden J J , Nilsson U R
Published: January 2020

Comedones, the contents of acne lesions, were shown to consume scomplement hemolytic activity in normal serum. This consumption was stimulated by the addition of serum from patients with inflammatory acne. Absorption of acne serum with Propionibacterium acnes cells removed all stimulating activity. Immunoelectrophoretic analysis of serum incubated with comedones revealed the conversion of C3 and factor B in normal serum. The addition of acne serum resulted in cleavage of C4. In serum treated with ethylene glycol-bis(beta-aminoethyl ether)-N,N'-tetraacetic acid, only C3 and factor B were converted. This indicates that comedones may activate complement by either the classical or the alternative pathway. It is suggested that P. acnes cells in comedonal material are responsible for the complement activation.
Behavior of Vaccine Revertants of Temperature-Sensitive Mutants of Influenza Virus in Ferret Tracheal Organ Culture
Authors: Mostow Steven R. , Hopkins Janet A. , Wright Peter F.
Published: January 2020

A live attenuated influenza vaccine candidate was not genetically stable when administered to some children who lacked antibody to surface proteins of the virus. To obtain additional biological information about these revertants, the vaccine strain, the wild-type parental strain, and isolates recovered from inoculated children during a vaccine trial were evaluated in ferret tracheal organ culture for effects on the ciliated epithelium and replication at both permissive and restrictive temperatures. The studies revealed that the vaccine strain destroyed cilia and replicated to high titer at its permissive temperature (33°) but caused minimal damage and replicated to very low titer at its restrictive temperature (37°C). The wild-type parent destroyed cilia at both 33 and 37°C. Isolates which were no longer temperature sensitive (ts
+
) destroyed cilia at both restrictive and permissive temperatures and grew to high titer. Isolates which retained the
ts
phenotype behaved as the vaccine strain in this system. The ts
+
virus recovered from volunteers behaved like the wild-type parent, which suggests that these viruses had not merely lost their
ts
phenotype, but had undergone reversion to wild type. Important information about the genetic stability of temperature-sensitive influenza vaccine strains recovered from volunteers can be obtained by evaluating them in ferret tracheal organ culture.
Depression of contact sensitivity by Pseudomonas aeruginosa-induced suppressor cells which affect the induction phase of immune response
Authors: Garzelli C , Colizzi V , Campa M , Bozzi L , Falcone G
Published: January 2020

The cellular basis of depression of contact sensitivity to oxazolone in mice injected with Pseudomonas aeruginosa was studied. Cells from draining lymph nodes of mice sensitized with oxazolone 18 h previously were able to induce contact sensitivity to normal mice when administered in their footpads. In contrast, cells from draining lymph nodes of P. aeruginosa-injected and oxazolone-sensitized donors failed to induce contact sensitivity when injected in the footpad of normal mice and were capable of actively blocking the immunizing process brought about by lymph node cells from sensitized mice when injected together in the footpad of normal recipients. The P. aeruginosa-induced suppressor cells required antigenic stimulation, had precursors sensitive to cyclophosphamide, and did not affect the effector mechanisms of contact sensitivity. Thus, the results suggest that P. aeurginosa depresses contact sensitivity to oxazolone by enhancing the activity of suppressor cells which normally arise during the sensitization process and which affect the afferent limb of the immune response, probably by inhibiting the normal recruitment of T lymphocytes in the draining lymph nodes.
Ability of enriched immune T cells to confer resistance in hamsters to infection with Treponema pertenue
Authors: Chan J K , Schell R F , LeFrock J L
Published: January 2020

This investigation presents the first direct evidence that T cells are involved in resistance to challenge with Treponema pertenue. Enriched T cells from immune hamsters were obtained by sequential filtration through glass and nylon-wool columns. This procedure removed the majority of functional antibody-producing and immunoglobulin-bearing cells. The fractionated cell suspensions were less responsive to stimulation by phytohemagglutinin, lipopolysaccharide, and dextran sulfate, but they were enriched with antithymocyte-sensitive cells and were more responsive to stimulation with concanavalin A. Hamsters receiving fractionated or unfractionated immune cells had no cutaneous lesions 21 days after infection and had significantly lower lymph node weights and fewer treponemes per node than hamsters that received fractionated or unfractionated normal cells. Resistance was transferred with immune cell suspension enriched in T cells despite an absence of anamnestic antibody response to specific treponemal antigens.
Intoxication of cells from different-aged embryos by diphtheria toxin
Authors: Iglewski W J , Taylor A , Hodges R , Tolle J
Published: January 2020

Different methods were used to assay diphtheria toxin sensitivity of fibroblast and heart cell cultures from chicken embryos of various ages. As defined by inhibition of protein synthesis, fibroblasts from 18-day and younger embryos respond more rapidly to toxin than fibroblasts from older embryos. The response of heart cells cultures is independent of the age of the embryos and is similar to the response of fibroblasts from 18-day embryos. Since the EF-2 content is 10-fold less in fibroblasts from 21-day-old embryos, the different responses of protein synthesis to intoxication appear to reside at the membrane level. Cytotoxicity assays in cell culture and in vivo toxin sensitivity assays show that cells from both young and old embryos, as well as whole embryos, are equally sensitive to toxin. Thus, short-term (5-h) measurements of inhibition of protein synthesis are insufficient for determining the relative sensitivity of cells to intoxication as defined by cell death.
Longitudinal investigation of the role of Streptococcus mutans in human fissure decay
Authors: Loesche W J , Straffon L H
Published: January 2020

A prospective study was initiated in order to detect changes in the levels and proportions of Streptococcus mutans, S. sanguis, and lactobacilli before and at the time of caries development on occlusal fissures. The bacteriological analysis was performed on 195 teeth that received four examinations at approximately 6-month intervals. The data obtained from 42 carious fissures and 153 caries-free fissures strongly indicated an etiological role for S. mutans in most of the diagnosed fissure lesions. This was demonstrated by the longitudinal analysis, which showed the proportions of S. mutans to increase significantly at the time of caries diagnosis, and by cross-sectional comparisons, which showed that the proportions of S. mutans in the carious fissures were significantly higher than in caries-free fissures. Three subjects who had a low caries expereince developed five new carious lesions. Lactobacilli were prominent members of the caries-associated flora in these subjects greatly outnumbering S. mutans. The levels and proportions of S. sanguis tended to be higher in the caries-free fissures. Altho1gh the results are striking in that they implicate S. mutans in fissure decay, they show that clinical decay can occur in a few instances in the absence of detectable S. mutans, as was observed in the fissures high in lactobacilli.
Experimental vaginal colonization and mother-infant transmission of group B streptococci in rats
Authors: Ancona R J , Ferrieri P
Published: January 2020

An animal model for group B streptococcal vaginal colonization and neonatal acquisition was developed with albino rats. Intravaginal inoculation of genital isolates of group B streptococci of serotypes Ia, II, and III either once or on 3 successive days resulted in carriage of the organisms for 7 days or longer in 26% of the virgin animals and 43% of the pregnant animals. Throat and perianal cultures of the offspring of pregnant rats revealed that 51% of the rat pups acquired the organisms at some time. Litter exchange studies were done to explore the contributions of environmental and intralitter spread. Significantly more infants born to mothers with positive vaginal cultures acquired the organisms than infants of culture-negative mothers who were suckled by positive adoptive mothers. However, 13% of the offsprinital cultures acquired group B streptococci. This model may be valuable in understanding the dynamics of vaginal carriage and mother-infant transmission of group B streptococci.
Effects of a Single Hit from the Alpha Hemolysin Produced by
Escherichia coli
on the Morphology of Sheep Erythrocytes
Authors: Jorgensen Sally E. , Hammer Robert F. , Wu Grace K.
Published: January 2020

Scanning electron micrographs of sheep erythrocytes showed that attachment of the alpha hemolysin produced by
Escherichia coli
resulted in the formation of spherocytes, with 10 to 20 small projections spaced relatively evenly over the surface of the erythrocyte membrane. This shape change was induced within 5 min after treatment. If the hemolysin concentration was reduced to a level which would lyse only a fraction of the total erythrocytes, the affected cells were easily identified against a background of normal, unaffected cells. Unlike sodium lauryl sulfate and other amphipathic agents which enter cell membranes and increase their flexibility, low concentrations of hemolysin did not provide protection against hypotonic hemolysis. These findings indicate that the surface projections were not the result of membrane expansion caused by incorporation of hemolysin into the outer portion of the lipid bilayer. The ability of a given amount of hemolysin to release a constant amount of hemoglobin in the presence of increasing concentrations of red cells confirmed that a single hit is sufficient for lysis. These results suggest that a single hemolysin molecule can bind to a sheep erythrocyte and trigger internal reactions which result in the derangement of membrane integrity at multiple sites on the surface. Confirmation of one-hit kinetics indicates that measurement of
E. coli
hemolysin activity should be carried out at low ratios of hemolysin to erythrocyte to decrease the possibility of multiple hits on a single cell.
Host defenses in experimental rickettsialpox: genetics of natural resistance to infection
Authors: Anderson G W , Osterman J V
Published: January 2020

The genetic basis for natural resistance to lethal infection with Rickettsia akari was studied in over 25 inbred strains, inbred hybrids, and outbred stocks of mice. Inbred mice infected intraperitoneally with the Kaplan strain of R. akari demonstrated three levels of response, susceptible (C3H/HeJ), intermediate (A/HeJ, A/J, A/WySn, BALB/cDub, BALB/cJ, and SJL/J), and resistant (AKR/J, AL/N, BALB/cAnN, BALB/cNCr1BR, C3H/HeN, C57BL/6J, C57L/J, CBA/J, DBA/2J, and SWR/J). No correlation was evident between the six H-2 haplo-types tested and susceptibility to Kaplan infection. Four outbred mouse stocks, Dub: (ICR), Wrc:(ICR), Caw:(CF1), and Mai:(S) were all resistant. The F1 inbred hybrids of resistant X resistant (AKD2F1/J), resistant X intermediate (CB6F1/U), intermediate X intermediate (CAF1/J), and resistant X susceptible (C3D2F1/J) parents were all resistant. The F2 and parental backcross generations of C3H/HeJ and DBA/2J hybrids yielded ratios of resistant to susceptible mice that suggested resistance was under multigeneic control. Susceptible mice (C3H/HeJ) were capable of mounting an immune response, since prior infection with the avirulent Hartford strain of R. akari rendered them resistant to subsequent lethal challenge with the Kaplan strains.
Arabinosylthymine: suppressor of hamster immunoglobulin M formation during primary immune response
Authors: Barnett J M , McGowan J J , Gentry G A
Published: January 2020

The effect of 1-beta-D-arabinofuranosylthymine (araT) and thymidine (TdR) on the primary and secondary humoral immune responses to Brucella abortus and sheep erythrocytes was investigated. The data indicate that both agents suppress the primary humoral response without significantly altering the secondary response. In addition, the mercaptoethanol-sensitive immunoglobulin component of the total antibody titer was lowered to a much greater extent than was the mercaptoethanol-resistant immunoglobulin component by treatment with ara-T or TdR. Further, the response to B. abortus (a T-independent antigen) seemed to be suppressed more than the response to sheep erythrocytes, a T-dependent antigen. This suggests that subpopulations of lymphocytes may express different sensitivities to araT and TdR.
Comparative Antigenicity and Immunogenicity of A/USSR/77 Influenza Vaccines in Normal and Primed Mice
Authors: McLaren Colin , Grubbs George E. , Staton Eldridge , Barthlow William , Quinnan Gerald , Ennis Francis A.
Published: January 2020

In response to the threat of wide-spread epidemics of influenza in the United States due to the A/USSR/77 strain of virus, vaccines containing A/USSR/77 virus were prepared by four manufacturers. The vaccines were standardized by immunological measurements of viral hemagglutinin and were tested for their ability to induce serum hemagglutination-inhibiting antibodies in mice and to protect the animals against challenge infection with A/USSR/77 virus. Whole-virus and subunit virus vaccines were found to be equally efficacious, in contrast to our previous findings with vaccines prepared from other influenza virus strains. The effect of priming animals by infection with representative viruses of earlier eras on their response to A/USSR/77 vaccines was also studied. Enhanced responses were noted to both subunit and whole-virus A/USSR/77 vaccines in animals primed with viruses prevalent before 1957; higher antibody titers were induced with the subunit vaccine. A high degree of heterologous protection to A/USSR/77 challenge infection was found in mice primed with virus strains having hemagglutinin antigens unlike those of A/USSR/77 virus. Comparison of the responses of mice with those of humans inoculated with the same vaccines showed a similarity in many instances, with higher responses in those individuals primed with H0N1 and H1N1 viruses than in younger vaccinees.
Biochemical and morphological characterization of the killing of human monocytes by a leukotoxin derived from Actinobacillus actinomycetemcomitans
Authors: Taichman N S , Dean R T , Sanderson C J
Published: January 2020

A potent, heat-labile leukotoxic material was extracted from Actinobacillus actinomycetemcomitans (strain Y4), an anaerobic gram-negative microorganism originally isolated from subgingival plaque in a patient with juvenile periodontitis. The cytopathic effects of Y4 toxin on purified monocytes were studied by the extracellular release of radioactive cytoplasmic markers and cell enzymes and by time-lapse microcinematography. Y4 toxin rapidly bound to the cells, producing dose- and time-dependent alterations culminating in cell death and release of intracellular constituents into the culture medium. The evidence to be presented suggests that the cell membrane of the monocyte may be the primary target in the development of these phenomena. Previous studies have shown that Y4 toxin also kills human polymorphonuclear leukocytes but not other cell types. It is conceivable that disruption of polymorphonuclear leukocytes and monocytes by Y4 toxin in the gingival crevice area may be relevant in the pathogenesis of juvenile periodontitis.
Selective suppression of granuloma formation and delayed hypersensitivity in rabbits
Authors: Schroff R W , Heise E R , Myrvik Q N , Shannon B T
Published: January 2020

The relationship between dermal delayed hypersensitivity (DH) and granulomatous hypersensitivity was studied in rabbits sensitized with killed mycobacteria. Specific antigen challenge of sensitized animals resulted in extensive pulmonary granulomatous inflammation and induced suppression of both dermal DH and dermal granuloma formation. Whereas suppression of DH was concomitant with pulmonary granuloma formation, as is the case in a number of granulomatous diseases, a causal relationship between the two did not exist. Both DH and dermal granulomatous hypersensitivity were significantly suppressed whether or not the antigen challenge was of a granulomagenic (particulate) or nongranulomagenic (soluble) form. The data presented indicate that granulomatous hypersensitivity and DH are selectively suppressed with regard to different anatomical sites.
Development of resistance with host age to adhesion of K99+ Escherichia coli to isolated intestinal epithelial cells
Authors: Runnels P L , Moon H W , Schneider R A
Published: January 2020

When isolated intestinal epithelial cells from neonatal and older pigs, calves, and mice were tested for adhesion by K99+ enterotoxigenic Escherichia coli, cells from older animals were resistant to adhesion.
Conservation of cell wall peptidoglycan by strains of Streptococcus mutans and Streptococcus sanguis
Authors: Mychajlonka M , McDowell T D , Shockman G D
Published: January 2020

Turnover of the cell wall peptidoglycan fraction of six different strains of Streptococcus mutans and eight different strains of Streptococcus sanguis was examined. Cells were grown in the presence of [3H]lysine and [14C]leucine for at least eight generations and then chased in growth medium lacking the two labels. At intervals during the chase, samples of cultures were removed, and the amounts of the two labeled precursors remaining in the peptidoglycan and protein fractions were quantitated. Similar experiments were done in which the pulse-labeling technique was used. In addition, cells were labeled in the presence of tetracycline or penicillin, chased with growth medium containing no inhibitor, and assayed at intervals during the chase for the amount of [3H]lysine present in peptidoglycan fractions. Studies of cultures of S. mutans strains FA-1, OMZ-61, OMZ-176, 6715, GS-5, and Ingbritt and of S. sanguis strains 10558, M-5, Wicky, DL-101, DL-1, 71X26, and 71X48 maintained in the exponential phase of growth in a chemically defined medium failed to show evidence of loss of insoluble peptidoglycan via turnover. Similarly, for the strains of S. mutans, insoluble peptidoglycan assembled during 2 h of benzylpenicillin or tetracycline treatment was also conserved during recovery from growth inhibition.
Resistance to highly virulent mouse hepatitis virus acquired by mice after low-virulence infection: enhanced antiviral activity of macrophages
Authors: Taguchi F , Yamada A , Fujiwara K
Published: January 2020

As early as 1 to 2 days after intranasal inoculation with a mouse hepatitis virus of low virulence, MHV-S, susceptible DDD mice became fully resistant to a normally lethal challenge with a highly virulent MHV-2. The resistance of MHV-S-pretreated mice was correlated with significantly decreased MHV-2 multiplication in the liver, spleen, and brain. Infection with MHV-S did not induce a high level of interferon in DDD mice, and no neutralizing antibody against MHV-2 was detected in the sera of mice until day 6 of MHV-S infection. The multiplication of MHV-2 was suppressed in peritoneal cells (PC) in vivo and peritoneal adherent cells (PAC) in vitro of MHV-S-pretreated mice was compared with those of normal mice. This suppression of virus multiplication was demonstrated in PAC collected during days 1 to 3 of infection but not in PAC collected from day 5 on. PC from MHV-S-pretreated mice were also suppressive to MHV-2 growth in DK cells as compared with PC from normal mice. By treatment of MHV-S-pretreated mice with silica, suppression of virus growth in the liver was partially diminished. These findings suggest that increased suppression of MHV-2 growth in PAC (mostly macrophages) of MHV-S-pretreated mice is responsible for resistance.
Chemical and Immunological Study of Colicins E
1
, K, A, and Q
Authors: Dandeu Jean-Pierre
Published: January 2020

Colicins are proteins and, regardless of their origin, can exist in one of two forms, free or bound. When bound, the other constituent is a polysaccharide, but the ratio of the bound form to the free form is dependent on whether the colicin is extracted from an induced or a noninduced strain. Even after extensive purification, traces of polysaccharides persist, and this may be responsible for the partial resistance of colicins to denaturation. The different colicins examined showed differences in their electrophoretic mobility as well as in their amino acid content. However, similarities do exist as has been shown by the demonstration of a common antigen site “L” to colicins E
1
, Q, and H.
Effect of route of Mycobacterium bovis BCG administration on induction of suppression of sporozoite immunity in rodent malaria
Authors: Smrkovski L L
Published: January 2020

Intravenous immunization of mice with 16,000, 60Co--gamma-irradiated, attenuated sporozoites produced solid immunity to sporozoite-induced malaria when the mice were challenged 21 days after immunization. In contrast, mice injected by various routes with 10(7) viable units of Mycobacterium bovis (BCG) before immunization with irradiated sporozoites were not completely immune to challenge. The extent of reduced protection against viable sporozoites demonstrated with these animals was dependent upon the injection route mycobacteria. The intravenous administration of BCG induced the greatest degree of suppression, followed by the intraperitoneal and subcutaneous routes. BCG injected intramuscularly before sporozoite immunization did not suppress development of immunity. In contrast, mice injected with BCG after immunization with attenuated sporozoites exhibited a lesser degree of suppression. In these animals, only the intravenous injection of mycobacteria reduced immunity.