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Biomedical subjects

R G Webster

Publications and source records attributed to R G Webster.

At least 307 records · Page 17Linked to original sources
PubMed1983

Sequence of the hemagglutinin gene from influenza virus A/Seal/Mass/1/80.

A double-strand DNA copy of the influenza virus A/Seal/Mass/1/80 (H7N7) [seal] hemagglutinin (HA) gene was cloned into the plasmid pAT153/PvuII/8 and sequenced to deduce the primary amino acid sequence. The gene is 1731 nucleotides long and codes for a protein of 560 amino acids with a nonglycosylated molecular weight of 62098 Da. The deduced amino acid sequence displays similarities to all other sequenced hemagglutinins by retaining six of seven potential glycosylation sites, showing conversation in the number and position of cysteine residues, conservation in the fusion and anchor peptides, and conservation in the putative receptor site of the molecule. However, three features of the primary amino acid sequence could be distinguished from the H7 amino acid sequence of A/fowl plague/Rostock/34 (FPV), another avian H7 influenza virus which does not produce disease in mammals. First, the seal HA sequence has three fewer amino acids in the connecting peptide region of the HA than FPV. This lack of multiple basic amino acids in the connecting peptide is similar to that found in avirulent H7 avian strains and to mammalian serotypes H1, H2, and H3. Second, the seal HA has gained four additional proline residues, all in HA1, as compared to FPV. These residues may alter the tertiary structure of the HA and ultimately contribute to the biological features of this virus. Third, the seal HA has lost a potential carbohydrate attachment site at residue 149 which lies at the tip of the HA structure. The loss of this carbohydrate could alter the seal HAs interaction with host cell receptors.

Amino Acid Sequence↗
PubMed1983

Localization, synthesis, and activity of an antigenic site on influenza virus hemagglutinin.

This paper reports the antigenicity of the fusion region of the influenza virus hemagglutinin (HA). Two peptides, comprising the fusion region (residues 1-11 of the HA2 part of HA) of strain A and strain B influenza virus, were synthesized and their abilities to bind rabbit, goat, and human anti-influenza antibodies were determined. In addition, 30 anti-HA monoclonal antibodies were examined for their ability to bind the synthetic peptides. In quantitative immunoadsorbent titrations, the two peptides bound considerable amounts of antibodies in rabbit and goat antisera against virus or HA of the A or B strain as well as in several human sera from patients recovering from influenza A. Of the 30 anti-HA monoclonal antibodies, 5 bound completely and 4 bound partially to the peptides. Antibodies were raised in rabbits against the peptides by immunizing with peptide-bovine serum albumin conjugates or with the free peptides. Anti-peptide antibodies were bound by HA and by the intact virus of the respective strain. However, these antisera failed to exhibit significant virus neutralizing activity. In contrast, the monoclonal antibodies that reacted with these peptides inhibited viral infectivity. The results clearly show that residues 1-11 of HA2 represent an important antigenic site on influenza virus.

Animals↗
PubMed1983

Antigenic and biochemical analysis of field isolates of influenza B virus: evidence for intra- and inter-epidemic variation.

Detailed antigenic analysis using a panel of monoclonal antibodies was carried out on the haemagglutinin antigen of 53 influenza B viruses isolated from an epidemic in a single school. Thirteen distinguishable antigenic groupings of influenza B viruses could be detected but 26 of the viruses were in two groups (III and IV) which co-existed during the entire epidemic. Antigenically distinguishable influenza B viruses were isolated from an epidemic in a second nearby school. Influenza B viruses isolated from the two schools could be further distinguished by different electrophoretic mobilities of NS1 polypeptides and of genes 1, 2, 3 and 6, whereas viruses from a single school epidemic were very closely related as regards these biochemical characteristics. The findings are consistent with the hypothesis that the outbreak was initiated by a single individual who excreted antigenic mutants of which predominantly two spread and co-existed during the epidemic, although the additional occurrence of random mutations during the evolution of the epidemic cannot be excluded.

Antibodies, Monoclonal↗
PubMed1983

Antigenic characteristics and genome composition of a naturally occurring recombinant influenza virus isolated from a pig in Japan.

We performed antigenic analysis of the haemagglutinin and neuraminidase subunits of a recombinant virus (A/swine/Kanagawa/2/78) isolated from a pig in Japan in 1978, using a series of monoclonal antibodies to H1 (Hsw1) haemagglutinin and N2 neuraminidases of H2N2 and H3N2 viruses. Results obtained in haemagglutination inhibition tests with five monoclonal antibodies to the haemagglutinin of A/NJ/8/76 (H1N1) revealed that the haemagglutinin of three H1N1 and the recombinant viruses were indistinguishable from that of A/NJ/8/76. The neuraminidase of A/swine/Kanagawa/2/78 was found to be antigenically similar to A/Kumamoto/22/76 (H3N2, A/Victoria/3/75-like strain). The oligonucleotide maps of the entire RNAs of H1N1, H1N2 and H3N2 viruses showed that A/swine/Kanagawa/2/78 (H1N2) virus was more similar to swine (H1N1) virus than to A/Kumamoto/22/76 (H3N2) virus. Radioactive cDNA was prepared by reverse transcription of the recombinant virus RNA using a dodecadeoxyribonucleotide primer and used in DNA-RNA hybridization experiments. The results obtained in molecular hybridization based on blotting procedures showed that all cDNA segments except gene 6 hybridized efficiently with RNAs of swine (H1N1) influenza virus. The sixth cDNA segment was homologous to the corresponding RNA segment of H3N2 virus. The genetic relatedness of A/swine/Kanagawa/2/78 (H1N2) with either A/swine/Kanagawa/4/78 (H1N1) or A/Kumamoto/22/76 (H3N2) was clearly established by hybridization between the cDNA segment probes and viral RNA. It was concluded that the neuraminidase gene of A/swine/Kanagawa/2/78 (H1N2) was derived from a human H3N2 virus, while the seven other genes were from a swine H1N1 virus.

Animals↗
PubMed1983

Evaluation of the A/Seal/Mass/1/80 virus in squirrel monkeys.

An influenza A virus isolated from seals [A/Seal/Mass/1/80 (H7N7)] and an isolate of this virus obtained from a human conjunctiva were evaluated for replication and virulence in squirrel monkeys. When the seal virus was administered intratracheally, it replicated in lungs and nasopharynges and induced illness almost to the same extent that a human influenza A virus [A/Udorn/72 (H3N2)] did. In one monkey that died of pneumonia, the seal virus was recovered from spleen, liver, and muscle as well as lung. After conjunctival administration in monkeys, the seal virus replicated to a peak titer in the conjunctivae 30-fold greater than that attained by the human virus, but this difference was not statistically significant. In contrast, the seal virus replicated less well than the human virus in the tracheae and nasopharynges when administered by the conjunctival route. These results indicate that the seal virus can replicate efficiently in primates, that it can spread systemically, and that it might differ from human virus in being able to replicate slightly better in primate conjunctival tissue.

Animals↗
PubMed1983

Antigenic analysis of H1N1 viruses isolated in the Houston metropolitan area during four successive seasons.

We evaluated the antigenic stability of viruses within the H1N1 subtype, using 307 isolates spanning four winter seasons. The isolates from each seasonal period appeared relatively homogenous in hemagglutination inhibition tests employing ferret antisera. However, a panel of seven monoclonal antibodies to A/USSR/90/77 detected extensive micro-heterogeneity. Antigenic variation occurred in the hemagglutinin antigen within a few weeks after the initial appearance of A/USSR/90/77-like strains in 1977-78 season as evidenced by low reactivity to one or several of the monoclonal antibodies. By the end of the season, few of the isolates reacted with the complete panel. Antigenic heterogeneity of the hemagglutinin was detected among H1N1 viruses throughout each epidemic interval. Some of the antigenic changes detected by monoclonal antibodies appeared on isolates in succeeding years, but others were restricted to a few strains isolated during a given year. The cumulative nature of some of these antigenic changes was indicated by the observation that 20 (19%) of 107 isolates examined in the fourth season failed to react with five of the monoclonal antibodies. Strains similar to most reference variants from around the world circulated in the Houston community.

Antibodies, Monoclonal↗
PubMed1983

Heterogeneity of influenza B viruses.

Antigenic analysis of influenza B strains isolated in 1981-82 from England, Japan, and the USA, using a panel of monoclonal antibodies to the haemagglutinin of B/Oregon/5/80, showed considerable heterogeneity among the isolates, the majority of which had distinct reactivity patterns. Antigenically similar viruses were isolated from England, Japan, and the USA, and heterogeneity was detected among isolates from each country. Further studies are needed to determine whether this marked heterogeneity reflects different cocirculating strains or antigenic drift during an epidemic. The monoclonal antibodies failed to detect any difference between influenza B isolates from patients with Reye's syndrome and those circulating in the community.The monoclonal antibodies, each recognizing different determinants on the haemagglutinin of B/Oregon/5/80, were pooled and compared with ferret antisera to determine if the pool could be used as a reference reagent. The monoclonal antibody pool discriminated between isolates, contained no non-specific inhibitors of haemagglutination, and avoided the problems associated with differences between ferret antisera. In general, viruses that were shown to be antigenically different by ferret antisera were also different with the pooled monoclonal antibodies, but further studies are required to determine the optimal mixture of antibodies that will detect epidemiologically significant differences between strains.

Animals↗
PubMed1983

Analysis of antigenic variation in equine 2 influenza A viruses.

Influenza outbreaks involving viruses of the H3N8 subtype (equine 2) often occur in vaccinated horses. For this reason, a series of influenza viruses of the H3N8 subtype were examined to determine if antigenic variation could be detected in isolates during the period 1963-81. Antigenic analyses with post-infection ferret sera and monoclonal antibodies showed that the haemagglutinins of recent isolates were antigenically distinguishable from the prototype A/eq/Miami/1/63 and that antigenically distinguishable groups of equine 2 viruses co-circulate in the horse population. Based on these studies, it is recommended that a recent equine strain, A/equine/Fontainebleu/1/79 or A/equine/Kentucky/1/81, serve as an additional prototype strain for this subtype.Antigenic variation in equine 2 viruses may be of epidemiological significance, yet the overall conservation of these strains makes it unlikely that vaccine failures can be attributed solely to antigenic changes in these viruses. A sufficiently potent vaccine, containing a current representative of the most prevalent equine 2 strain, may improve the protection afforded by equine vaccines.

Animals↗
PubMed1983

The equilibrium constant for the interaction between a monoclonal Fab fragment and an influenza virus neuraminidase.

The affinity or equilibrium constant between an Fab fragment derived from monoclonal IgG directed against influenza virus neuraminidase was measured as 4.1 X 10(7) M-1. The method, which makes use of an air-driven ultracentrifuge, is simple and uses extremely small amounts (10(-11) mol) of material. Furthermore, interpretation of the data is based on sound theoretical considerations. The technique also allows m.w. of the interacting species to be measured and the stoichiometry of the reaction to be determined.

Animals↗
PubMed1982

Reassortant virus derived from avian and human influenza A viruses is attenuated and immunogenic in monkeys.

An influenza A reassortant virus that contained the hemagglutinin and neuraminidase genes of a virulent human virus, A/Udorn/72 (H3N2), and the six other influenza A virus genome segments from an avirulent avian virus, A/Mallard/New York/6750/78 (H2N2), was evaluated for its level of replication is squirrel monkeys and hamsters. In monkeys, the reassortant virus was as attenuated and as restricted in its level of replication in the upper and lower respiratory tract as its avian influenza virus parent. Nonetheless, infection with the reassortant induced significant resistant to challenge with virulent human influenza virus. In hamsters, the reassortant virus replicated to a level intermediate between that of its parents. These findings suggest that the nonsurface antigen genes of the avian parental virus are the primary determinants of restriction of replication of the reassortant virus in monkeys. Attenuation of the reassortant virus for primates is achieved by inefficient functioning of the avian influenza genes in primate cells, while antigenic specificity of the human influenza virus is provided by the neuraminidase and hemagglutinin genes derived from the human virus. This approach could lead to the development of a live influenza A virus vaccine that is attenuated for man if the avian influenza genes are similarly restricted in human cells.

Animals↗
PubMed1982

Mass mortality of harbor seals: pneumonia associated with influenza A virus.

More than 400 harbor seals, most of them immature, died along the New England coast between December 1979 and October 1980 of acute pneumonia associated with influenza virus, A/Seal/Mass/1/180 (H7N7). The virus has avian characteristics, replicates principally in mammals, and causes mild respiratory disease in experimentally infected seals. Concurrent infection with a previously undescribed mycoplasma or adverse environmental conditions may have triggered the epizootic. The similarities between this epizootic and other seal mortalities in the past suggest that these events may be linked by common biological and environmental factors.

Animals↗
PubMed1982

A comparison of two anti-neuraminidase monoclonal antibodies by complement activation.

The specificities of two anti-neuraminidase monoclonal antibodies have been compared by their ability to fix complement. They were found to differ to some extent in their reactivity with a range of N2 influenza virus. Thus, as in the case of anti-hemagglutinin antibodies, anti-neuraminidase monoclonal antibodies are able to detect subtle structural changes in the vital antigen. Although both monoclonal antibodies fixed complement with intact virus, neither one fixed complement when complexed with isolated neuraminidase "heads".

Animals↗
PubMed1982

Human influenza A viruses in pigs: isolation of a H3N2 strain antigenically related to A/England/42/72 and evidence for continuous circulation of human viruses in the pig population.

An influenza virus strain isolated in Northern Italy in 1977 was identified as belonging to the H3N2 subtype (A/swine/Italy/1850/77). A close antigenic relationship to the human strain A/England/42/72 was demonstrated. Serologic surveys of 548 pig sera from 53 farms in two provinces in Northern Italy demonstrated the existence of antibodies to the swine/Italy/1850/77 strain and to A/Hong Kong/1/68, A/Victoria/3/75 and H 1 N 1 (Hsw 1 N 1) strains in the pig population.

Animals↗