SEARCH · PubMed Health

Results for “Cross Protection”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,081 records · Page 60Linked to original sources

PubMed1992

Scattering of the rRNA genes on the physical map of the circular chromosome of Leptospira interrogans serovar icterohaemorrhagiae.

Leptospira interrogans is a pathogenic bacterium with a low G+C content (34 to 39%). The restriction enzymes NotI, AscI, and SrfI cut the chromosome of L. interrogans serovar icterohaemorrhagiae into 13, 3, and 5 fragments separable by one- and two-dimensional pulsed-field gel electrophoresis (PFGE). The genome is composed of a circular 4.6-Mbp chromosome and a 0.35-Mbp extrachromosomal element. A physical map of the chromosome was constructed for NotI, AscI, and SrfI by using single and double digests, or partial NotI digests obtained at random or by cross-protection of NotI sites by FnuDII methylase, and linking clones. rRNA genes were found to be widely scattered on the chromosome.

Base Sequence↗

PubMed1997

Heat shock regulation of sigmaS turnover: a role for DnaK and relationship between stress responses mediated by sigmaS and sigma32 in Escherichia coli.

The cellular level of the rpoS-encoded sigmaS subunit of RNA polymerase increases in response to various stress situations that include starvation, high osmolarity, and shift to acid pH, and these different stress signals differentially affect rpoS translation and/or sigmaS stability. Here we demonstrate that sigmaS is also induced by heat shock and that this induction is exclusively due to an interference with sigmaS turnover. Some sigmaS-dependent genes exhibit similar heat shock induction, whereas others are not induced probably because they need additional regulatory factors that might not be present under conditions of heat shock or exponential growth. Despite its induction, sigmaS does not seem to contribute to heat adaptation but may induce cross-protection against different stresses. While sigmaS is not involved in the regulation of the heat shock sigma factor sigma32, the heat shock protein DnaK has a positive role in the posttranscriptional control of sigmaS. The present evidence suggests that DnaK is involved in the transduction of two of the signals that result in reduced sigmaS turnover, i.e., heat shock and carbon starvation. Heat shock induction of sigmaS also clearly indicates that a cessation of growth or even a reduction of the growth rate is not a prerequisite for the induction of sigmaS and sigmaS-dependent genes and underscores the importance of sigmaS as a general stress sigma factor.

Bacterial Proteins↗

PubMed1997

Adaptation to nutrient starvation in Rhizobium leguminosarum bv. phaseoli: analysis of survival, stress resistance, and changes in macromolecular synthesis during entry to and exit from stationary phase.

The nitrogen-fixing bacterium Rhizobium leguminosarum bv. phaseoli often has to survive long periods of starvation in the soil, when not in a useful symbiotic relationship with leguminous plants. We report that it can survive carbon, nitrogen, and phosphorus starvation for at least 2 months with little loss of viability. Upon carbon starvation, R. leguminosarum cells were found to undergo reductive cell division. During this period, they acquired the potential for long-term starvation-survival, levels of protein, DNA, and RNA synthesis were decreased to base levels, and pool mRNA was stabilized. The starved cells are ready to rapidly restart growth when nutrients become available. Upon addition of fresh nutrients, there is an immediate increase in the levels of macromolecular synthesis, pool mRNA destabilizes, and the cultures enter exponential growth within 5 to 8 h. The starved cells were cross-protected against pH, heat, osmotic, and oxidative shock. These results provide evidence for a general starvation response in R. leguminosarum similar to that previously found in other bacteria such as Escherichia coli and Vibrio sp.

Bacterial Proteins↗

PubMed1998

Cloning, sequencing, and phenotypic characterization of the rpoS gene from Pseudomonas putida KT2440.

A gene homologous to the rpoS gene of Escherichia coli was cloned from a Pseudomonas putida KT2440 gene bank by complementation of the rpoS-deficient strain E. coli ZK918. The rpoS gene of P. putida complemented the acid sensitivity and catalase deficiency of the rpoS mutant of E. coli and stimulated expression of the RpoS-controlled promoter, bolAp1. The gene was sequenced and found to be highly similar to the rpoS genes of other gram-negative bacteria. Like in other gram-negative bacteria, a homolog of the nlpD gene was found upstream to the rpoS gene. A transcriptional fusion of the promoter of the P. putida rpoS gene to the luxAB genes from Vibrio harveyi was constructed and used as an inactivated allele of rpoS for gene replacement of the wild-type copy in the chromosome of P. putida. The resultant rpoS mutant of P.putida, C1R1, showed reduced survival of carbon starvation and reduced cross-protection against other types of stress in cells starved for carbon, in particular after a challenge with ethanol. Survival in soil amended with m-methylbenzoate was also reduced in the mutant strain P. putida C1R1. The RpoS protein of P. putida controls the expression of more than 50 peptides, which are normally expressed in cells after a short period of carbon starvation.

Amino Acid Sequence↗

PubMed1998

Extracellular signal molecule(s) involved in the carbon starvation response of marine Vibrio sp. strain S14.

The role of exogenous metabolites as putative signal molecules mediating and/or regulating the carbon starvation adaptation program in Vibrio sp. strain S14 was investigated. Addition of the stationary-phase supernatant extract (SSE) of Vibrio sp. strain S14 to logarithmic-phase cells resulted in a significant number of carbon starvation-induced proteins being up-regulated. Halogenated furanones, putative antagonists of acylated homoserine lactones (AHLs), inhibited the synthesis of proteins specifically induced upon carbon starvation. The effect of the furanone was the opposite of that caused by SSE with respect to the up- and down-regulation of protein expression, indicating that both the furanone and the putative signalling molecules were acting on the same regulatory pathway. Culturability was rapidly lost when Vibrio sp. strain S14 was starved in the presence of the furanone at a low concentration. The furanone also had a negative effect on the ability of carbon-starved cells to mount resistance against UV irradiation and hydrogen peroxide exposure. The SSE of Vibrio sp. strain S14 had the ability to provide cross-protection against the loss in viability caused by the furanone. We have further demonstrated that the SSE taken from low- as well as high-cell-density cultures of Vibrio sp. strain S14 induced luminescence in Vibrio harveyi. Taken together, the results in this report provide evidence that Vibrio sp. strain S14 produces extracellular signalling metabolites during carbon and energy starvation and that these molecules play an important role in the expression of proteins crucial to the development of starvation- and stress-resistant phenotypes.

Bacterial Proteins↗

PubMed2004

Ribosomal protein S1 specifically binds to the 5' untranslated region of the Pseudomonas aeruginosa stationary-phase sigma factor rpoS mRNA in the logarithmic phase of growth.

The rpoS gene encodes the stationary-phase sigma factor (RpoS or sigma(s)), which was identified in several gram-negative bacteria as a central regulator controlling the expression of genes involved in cell survival in response to cessation of growth (stationary phase) and providing cross-protection against various stresses. In Pseudomonas aeruginosa, the levels of sigma(s) increase dramatically at the onset of the stationary phase and are regulated at the transcriptional and posttranscriptional levels. The P. aeruginosa rpoS gene is transcribed as a monocistronic rpoS mRNA transcript comprised of an unusually long 373-bp 5' untranslated region (5' UTR). In this study, the 5' UTR and total protein extracts from P. aeruginosa logarithmic and stationary phases of growth were used in order to investigate the protein-RNA interactions that may modulate the translational process. It was observed that a 69-kDa protein, which corresponded to ribosomal protein S1, preferentially binds the 5' UTR of the rpoS mRNA in the logarithmic phase and not in the stationary phase. This is the first report of a protein-rpoS mRNA 5' UTR interaction in P. aeruginosa, and the possible involvement of protein S1 in translation regulation of rpoS is discussed.

5' Untranslated Regions↗

PubMed1961

Subclinical infection of dogs by canine-adapted measles virus evidenced by their subsequent immunity to canine distemper virus.

Moura, Roberto A. (Chas. Pfizer and Company, Inc., Terre Haute, Ind.) and Joel Warren. Subclinical infection of dogs by canine-adapted measles virus evidenced by their subsequent immunity to canine distemper virus. J. Bacteriol. 82:702-705. 1961.-Young dogs were inoculated with virulent measles virus which had been adapted to canine kidney or human amnion cell culture. None of the animals showed any clinical symptoms nor could virus be isolated from the blood, although measles-neutralizing and complement-fixing antibodies developed during convalescence. All dogs failed to develop antibody to canine distemper. However, when these and normal control animals were subsequently inoculated intracerebrally with virulent distemper virus, each of the controls succumbed to typical symptoms, whereas all of the measles-immune dogs survived. These results suggest that the cross-protection conferred by measles against canine distemper virus infection involves factors other than humoral antibody. The immunity persists for a considerable length of time.

Animals↗

PubMed1984

Isolation and serotyping of porcine rotaviruses and antigenic comparison with other rotaviruses.

Seven rotavirus strains were isolated in cell cultures from the intestinal contents of piglets with diarrhea. MA104 cells with pancreatin in the cell culture medium was the host system of choice for virus isolation and replication. A cell culture immunofluorescence test in which MA104 cells were used in microtiter plates was very effective for detecting and assaying rotaviruses. A plaque reduction neutralization test, cross-protection studies in gnotobiotic pigs, and electrophoresis of rotaviral double-stranded RNA were used for comparing viruses. Three strains produced plaques on initial isolation attempts, replicated well in cell cultures, and were antigenically very similar. We suggest that these three strains be considered porcine rotavirus serotype 1, with The Ohio State University (OSU) strain serving as the prototype. The OSU strain was distinct from bovine, simian, canine, and human (Wa and M) rotaviruses by plaque reduction neutralization. Four strains did not produce plaques on initial isolation attempts, were difficult to adapt to cell cultures, and were related to each other but were distinct from the serotype 1 strains. We suggest that the Gottfried (G) strain be tentatively considered as a prototype for porcine rotavirus serotype 2. The G strain was antigenically closely related to canine and simian rotaviruses and less so to human M rotavirus (human rotavirus serotype 3). Canine, simian, and human M rotaviruses were closely related. All seven porcine rotavirus strains caused diarrhea in gnotobiotic pigs. Cell-cultured vaccines of the OSU and G strains caused only mild or no diarrhea in gnotobiotic pigs, and protection occurred when such pigs were challenged with homologous, bur not heterologous, virulent viruses. A survey indicated that 94% of 274 porcine serum samples and 100% of 75 herds were serologically positive to the porcine OSU rotavirus.

Animals↗

PubMed1984

Bovine rotavirus serotypes and their significance for immunization.

Neutralization assays on calf fecal rotavirus with antisera to two previously described bovine rotavirus serotypes allowed the isolation of four rotaviruses belonging to a distinct third serotype. In a survey of 85 calf isolates, 80 rotaviruses belonged to serotype 1 (91%), 1 belonged to serotype 2 (1%), and 4 belonged to serotype 3 (5%). Serotypes 1 and 2 were shown to not cross-protect in a passive immunization experiment in gnotobiotic lambs. Ingestion of specific antiserum protected against infection with the homologous, but not heterologous, serotype. Rabbits with no previous exposure to rotavirus responded to sequential vaccination with bovine and human rotavirus serotypes with antibody specific to those serotypes, and the response did not broaden to include serotypes to which they had not been exposed. These factors suggested the need for multivalent rotavirus vaccines. By contrast, 47 adult cows on 11 farms had neutralizing antibodies to two bovine and three human rotavirus serotypes. After vaccination with one bovine rotavirus serotype, these cows produced a significant increase in antibody titers to these same five serotypes but not to two other serotypes to which they had no preexisting antibody. These results were interpreted to indicate that cows will respond heterotypically after monovalent vaccination to all rotavirus serotypes with which they have had experience and, therefore, that single serotype vaccination may be sufficient. This conclusion has practical importance for rotavirus immunization procedures.

Animals↗

PubMed1994

Distribution of serotypes and antimicrobial resistance of Streptococcus pneumoniae strains isolated in Brazil from 1988 to 1992.

Forty-two serotypes were identified among 288 Streptococcus pneumoniae strains isolated from patients living in Brazil. Serotyping was determined by the capsular typing test (Quellung reaction). Types 14 (10.4%), 6B (9.8%), 23F (8.0%), 5 (7.3%), 19F (6.9%), 6A (6.0%), and 1 and 4 (4.6%) were the most commonly identified strains. Two hundred twenty (76.4%) of the strains were of serotypes that are included in the 23-valent pneumococcal polysaccharide vaccine. If vaccine-related serotypes are also considered, the proportions of coverage in the vaccine are 82.3% (if type 6B alone is added) and 85.7% (if all the vaccine-related types are considered to be cross-protecting). Decreased susceptibility to penicillin, which was identified by using the 1-microgram oxacillin disk method as a screening test, was detected in 70 (26.7%) strains. The MICs of nine antimicrobial agents were determined by using the procedures recommended by the National Committee for Clinical Laboratory Standards. Seventy (35.9%) of the strains were resistant to tetracycline, 57 (29.2%) were resistant to sulfamethoxazole-trimethoprim, 3 (1.5%) were resistant to rifampin, 2 (0.80%) were resistant to penicillin, and 1 (0.5%) was resistant to chloramphenicol. The two penicillin-resistant strains were also resistant to or had decreased susceptibilities to cephalosporins. Forty-seven (17.9%) of the strains were intermediately resistant to penicillin, 17 (8.7%) were intermediately resistant to tetracycline, 13 (6.7%) were intermediately resistant to chloramphenicol, 12 (6.1%) were intermediately resistant to erythromycin, and 6 (3.1%) were intermediately resistant to rifampin.

Brazil↗

PubMed1999

Genetic diversity of the 28-kilodalton outer membrane protein gene in human isolates of Ehrlichia chaffeensis.

The Ehrlichia chaffeensis 28-kDa outer membrane protein (p28) gene was sequenced completely by genomic walking with adapter PCR. The DNA sequence of the p28 gene was nearly identical to the previously reported sequence (N. Ohashi, N. Zhi, Y. Zhang, and Y. Rikihisa, Infect. Immun. 66:132-139, 1998), but analysis of a further 75 bp on the 5' end of the gene revealed DNA that encoded a 25-amino-acid signal sequence. The leader sequence was removed from the N terminus of a 30-kDa precursor to generate the mature p28 protein. A monoclonal antibody (MAb), 1A9, recognizing four outer membrane proteins of E. chaffeensis (Arkansas strain) including the 25-, 26-, 27-, and 29-kDa proteins (X.-J. Yu, P. Brouqui, J. S. Dumler, and D. Raoult, J. Clin. Microbiol. 31:3284-3288, 1993) reacted with the recombinant p28 protein. This result indicated that the four proteins recognized by MAb 1A9 were encoded by the multiple genes of the 28-kDa protein family. DNA sequence alignment analysis revealed divergence of p28 among all five human isolates of E. chaffeensis. The E. chaffeensis strains could be divided into three genetic groups on the basis of the p28 gene. The first group consisted of the Sapulpa and St. Vincent strains. They had predicted amino acid sequences identical to each other. The second group contained strain 91HE17 and strain Jax, which only showed 0.4% divergence from each other. The third group contained the Arkansas strain only. The amino acid sequences of p28 differed by 11% between the first two groups, by 13.3% between the first and third groups, and by 13.1% between the second and third groups. The presence of antigenic variants of p28 among the strains of E. chaffeensis and the presence of multiple copies of heterogeneous genes suggest a possible mechanism by which E. chaffeensis might evade the host immune defenses. Whether or not immunization with the p28 of one strain of E. chaffeensis would confer cross-protection against other strains needs to be investigated.

Amino Acid Sequence↗

PubMed2001

Characterization of newly emerging Newcastle disease virus isolates from the People's Republic of China and Taiwan.

Seven Newcastle disease (ND) virus (NDV) isolates which were recovered from ND outbreaks in chicken and pigeon flocks in China and Taiwan between 1996 and 2000 were genotypically and pathotypically characterized. By phylogenetic analysis of the fusion protein genes, isolates Ch-A7/96, Ch/98-3, Ch/99, Ch/2000, and TW/2000 were placed into two novel subgenotypes, VIIc and VIId. Isolate Ch/98-1 was grouped into subgenotype VIb, while Ch-W6/96 was proven to be a mixture of isolates Ch-A7/96 and Ch/98-1. These isolates were pathotyped as viscerotropic velogenic for Ch/98-3, Ch/99, Ch/2000, and TW/2000; neurotropic velogenic for Ch-A7/96; and mesogenic for Ch/98-1. Three separate, comparative, genetic analyses of the F genes, including genetic distance measurement, phylogenetic tree analysis, and residue substitution analysis, were performed with our isolates and selected NDV strains from GenBank. Results showed that the close genetic similarity provided evidence for the epidemiological linkage between the outbreaks in China and Taiwan and that the 1990s outbreaks in Asia, the Middle East, Africa, and Europe constituted the fourth panzootic of ND. In combination with epidemiological analysis, an evolutionary model of the NDV strains, representative of the direction of transmission within the NDV strains, was proposed, and epidemiology of NDV transmission was evaluated with emphasis on molecular aspects. Finally, a cross-protective experiment indicated that at least one strain (Ch-A7/96) among our NDV isolates was an antigenic variant, responsible for recent outbreaks of ND in vaccinated chicken flocks.

Animals↗

PubMed2002

Genotypic characteristics of two serotypes of Bartonella henselae.

The study of 16S rRNA gene sequences of all isolates of Bartonella henselae obtained in our laboratory and others from human patients or cats has revealed two genotypes according to the sequence of the 16S rRNA gene. Two isolates of these genotypes have previously been related to two different serotypes, and lack of cross-protection of the two serotypes has been demonstrated in cats. We investigated the grouping of eight strains of B. henselae on the basis of 16S ribosomal DNA, 35-kDa protein, Pap 31 protein, and internal transcribed spacer (ITS) gene sequencing; sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) profiles; and monoclonal antibody reactivity studies. Houston-1, 90-615, and SA2 strains showed the same patterns in SDS-PAGE, but they differed from the patterns of B. henselae isolates URBHLLY8, URBHLIE9, Cat6, Fizz, and CAL-1. Nine monoclonal antibodies derived from BALB/c mice immunized with B. henselae Houston-1 strain reacted only with strains Houston-1, 90-615, and SA2, and not with any other Bartonella strains. The two serogroups corresponded with two genotypes based on differences in the sequences of the genes encoding 16S rRNA, 35-kDa protein, and Pap 31 protein. Sequences of ITS genes were highly divergent among strains, as each had a unique sequence and the subdivision was not supported by DNA-DNA relatedness study. Study of 22 additional strains of B. henselae isolated from French bacteremic cats demonstrated that they all belong to one or the other of the proposed serotype or genotype.

Angiomatosis, Bacillary↗

PubMed2005

Clonal association between Streptococcus pneumoniae serotype 23A, circulating within the United States, and an internationally dispersed clone of serotype 23F.

Streptococcus pneumoniae is an important pathogen in the United States and is associated with significant morbidity and mortality. Since the introduction of the seven-valent conjugate vaccine, a significant decline in pneumococcal disease has been reported. However, surveillance for pneumococcal disease remains essential, as the extent of cross protection against vaccine-related serotypes is still unclear. Further, any increase in non-vaccine-related serotypes also needs monitoring. We report on a new clonal association between a vaccine-related serotype, serotype 23A, obtained as part of the Active Bacterial Core surveillance, with an established internationally dispersed Pneumococcal Molecular Epidemiology Network (PMEN) clone, clone Colombia(23F)-26. Sixty-two isolates of serotype 23A collected from sterile sites during a 2-year period (2002 and 2003) were characterized. Twenty-one (34%) isolates were penicillin nonsusceptible, although none were fully resistant. Pulsed-field gel electrophoresis and multilocus sequence typing analysis showed that 24 (39%) of the serotype 23A isolates shared either genetic identity or high genetic relatedness with PMEN clone Colombia(23F)-26. Extensive variability was noted within the sequenced region of pbp2b in two penicillin-nonsusceptible isolates as well as in PMEN clone Colombia(23F)-26, suggesting that these isolates probably acquired penicillin resistance independently. The emergence of such new serotype and genotype associations highlights the dynamic nature of the pneumococcal population, necessitating continuous monitoring in the post-vaccine era.

Adolescent↗

PubMed2006

Vaccination of pigs against swine influenza viruses by using an NS1-truncated modified live-virus vaccine.

Swine influenza viruses (SIV) naturally infect pigs and can be transmitted to humans. In the pig, genetic reassortment to create novel influenza subtypes by mixing avian, human, and swine influenza viruses is possible. An SIV vaccine inducing cross-protective immunity between different subtypes and strains circulating in pigs is highly desirable. Previously, we have shown that an H3N2 SIV (A/swine/Texas/4199-2/98 [TX98]) containing a deleted NS1 gene expressing a truncated NS1 protein of 126 amino acids, NS1black triangle126, was attenuated in swine. In this study, 4-week-old pigs were vaccinated with the TX98 NS1black triangle126 modified live virus (MLV). Ten days after boosting, pigs were challenged with wild-type homologous H3N2 or heterosubtypic H1N1 SIV and sacrificed 5 days later. The MLV was highly attenuated and completely protected against challenge with the homologous virus. Vaccinated pigs challenged with the heterosubtypic H1N1 virus demonstrated macroscopic lung lesions similar to those of the unvaccinated H1N1 control pigs. Remarkably, vaccinated pigs challenged with the H1N1 SIV had significantly lower microscopic lung lesions and less virus shedding from the respiratory tract than did unvaccinated, H1N1-challenged pigs. All vaccinated pigs developed significant levels of hemagglutination inhibition and enzyme-linked immunosorbent assay titers in serum and mucosal immunoglobulin A antibodies against H3N2 SIV antigens. Vaccinated pigs were seronegative for NS1, indicating the potential use of the TX98 NS1black triangle126 MLV as a vaccine to differentiate infected from vaccinated animals.

Animals↗

PubMed1978

Comparison of the genomic organization of Kirsten and Harvey sarcoma viruses.

Current studies were undertaken to compare the genomes of Kirsten murine sarcoma virus (Ki-MuSV), Harvey murine sarcoma virus (Ha-MuSV), and the replication-defective endogenous rat virus to understand the function of these viral RNAs. Genome organization and sequence homology were studied by fingerprinting large RNase T1-resistant oligonucleotides and by cross-protecting homologous oligonucleotides against RNase A and T1 digestion with complementary DNA prepared from each of the other viral RNA. Ki-MuSV and Ha-MuSV were found to share an extensive series of rat-derived oligonucleotides begining ca. 1 kilobase (kb) from the 3' end and extending to within 1.5 kb of the 5'end of Ki-MuSV RNA. The total map distance covered in ca. 5.5 kb. The eight oligonucleotides covering the 1.5 kb at the 5' end of Ki-MuSV RNA were not found in Ha-MuSV RNA. Five out of these eight oligonucleotides, however, could be designated with certainty to be of rat virus origin. Since Ha-MuSV is 6.5 kb in size and Ki-MuSV is 8 kb in size, the major difference between them is the 1.5 kb from the replication-defective endogenous rat virus sequences at the 5' end of Ki-MuSV not present in Ha-MuSV. Consistent with the difference in the genome structure, these two sarcoma viral RNA'S yielded distinct major translation products in cell-free systems, I.E., A 50,000-dalton polypeptide (P50) from Ki-MuSV and a 22,000-dalton polypeptide (p22) from Ha-MuSV. These polypeptides may provide the necessary protein makers for identifying in vivo virus-coded proteins.

Base Sequence↗

PubMed1987

Genomic heterogeneity among human and nonhuman strains of hepatitis A virus.

Cloned cDNA probes derived from the P1 and P2 regions of the genome of HM175 virus, a reference strain of human hepatitis A virus (HAV), failed to hybridize under standard stringency criteria with RNA from PA21 and PA33 viruses, two epizootiologically related HAV strains recovered from naturally infected New World owl monkeys. Hybridization of these probes to PA21 RNA was only evident under reduced stringency conditions. However, cDNA representing the 5' nontranslated region of the HM175 genome hybridized equally to HM175 and PA21 RNA under standard stringency conditions, while a probe derived from the 3' 1,400 bases of the genome yielded a reduced hybridization signal with PA21 RNA. In contrast, no differences could be discerned between HM175 virus and three other HAV strains of human origin (GR8, LV374, and MS1) in any region of the genome, unless increased stringency conditions were used. These results suggest that PA21 and PA33 are unique among HAV isolates and may represent a virus native to the owl monkey. Despite extremely poor homology within the P1 region, which encodes capsid polypeptides, monoclonal antibody analysis confirmed that the immunodominant neutralization epitopes of HAV were highly conserved between HM175 and PA21 viruses. Furthermore, experimental challenge of the owl monkey with successive PA33 and HM175 inocula confirmed a high but incomplete degree of cross-protection. Only one of six monkeys previously infected with PA33 developed recurrent hepatitis 28 days after intravenous HM175 challenge, while none of six monkeys previously infected with HM175 had demonstrable hepatitis following PA33 challenge. These data provide molecular evidence for the existence of HAV strains unique to nonhuman primate species and indicate that strict conservation of antigenic function may accompany substantial genetic divergence in HAV.

Animals↗

PubMed1988

Reduced yield of infectious pseudorabies virus and herpes simplex virus from cell lines producing viral glycoprotein gp50.

Pseudorabies virus (PRV) glycoprotein gp50 is the homolog of herpes simplex virus (HSV) glycoprotein D. Several cell lines that constitutively synthesize gp50 were constructed. Vero cells, HeLa cells, and pig kidney (MVPK) cells that produce gp50 all gave reduced yields of PRV and HSV progeny viruses when compared with the parent cell line or the same cell line transfected to produce a different protein. The reduction in virus yield was greatest at low multiplicities of infection. The Vero and HeLa cells that produce gp50 showed an even greater reduction in HSV yield than in PRV yield. This phenomenon may be an example in a herpesvirus of the interference observed in retroviruses or cross-protection in plant virus systems.

Animals↗