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Biomedical subjects

R G Webster

Publications and source records attributed to R G Webster.

At least 361 records · Page 20Linked to original sources
PubMed1980

Detection of monoclonal influenza antibodies synthesized in culture by hybridoma cells with a solid-phase indirect immunofluorometric assay.

A solid-phase indirect immunofluorometric assay for measuring reactions of mouse monoclonal antibodies with antigen has been developed, with influenza virus as a model. Purified IgG from hyperimmune rabbit sera is covalently linked to polyaminostyrene beads, to which influenza viruses are then bound immunologically to make solid-phase antigens. Alternatively, the virus is covalently coupled directly to the beads. Mouse antibodies, produced by hybridoma cells in culture, are reacted with constant amounts of solid-phase antigens, and then indirectly quantitated by adding FITC-labeled antimouse Ig and measuring the fluorescent intensity with a filter-fluorometer. The assay system permits rapid screening for low levels of antibodies synthesized by hybridoma cells in culture. It is about 25- to 150-fold more sensitive than hemagglutination inhibition tests in detecting monoclonal antibodies reactive with influenza virion HA protein.

Animals↗
PubMed1980

Monoclonal antibodies to influenza matrix protein: detection of low levels of matrix protein on abortively infected cells.

We have quantified the appearance of matrix (M-) protein on P815 mastocytoma cells infected with type A influenza virus using a monoclonal antibody specific for M-protein. In contrast to previously reported values, only low amounts (about 10(3) molecules/cell) of M-protein appear on the cell surface up to 16 h p.i. Since P815 cells are excellent targets for cross-reactive T-cell lysis 3 to 5 h after virus infection, when only about 10(2) M-protein sites are found on each cell surface. It appears less likely that the recognition of M-protein can account for the cross-reactivity of cytotoxic T-lymphocytes for different type A influenza viruses.

Animals↗
PubMed1980

The mechanism of antigenic drift in influenza viruses: analysis of Hong Kong (H3N2) variants with monoclonal antibodies to the hemagglutinin molecule.

Monoclonal antibodies to the hemagglutinin molecule of the Hong Kong variant, Mem/1/71 (H3N2), influenza virus were used to study antigenic drift in the H3N2 subtype of influenza viruses. Antigenic variants of Mem/1/71 (H3N2) were selected after a single passage of the virus in chick embryos in the presence of monoclonal antibody. The variants showed a marked reduction in the ability to react with the monoclonal antibody used in selection. The monoclonal antibodies could be divided into three groups based on their reactions with the variants, providing evidence for at least three nonoverlapping antigenic areas on the hemagglutinin molecule. Amino acid analysis of tryptic peptides of the hemagglutinin from these variants showed that a single amino acid substitution in the heavy polypeptide chain (HA1) of the hemagglutinin molecule accounted for the reduced antibody interactions, and that variants from each group exhibited sequence changes in different areas of the molecule. Sequence changes were also detected in the HA1 polypeptides of naturally occurring H3N2 variants, but in most cases the changes in the monoclonal antibody selected variants were different from the field strains. Antigenic analysis showed that most of the variants selected with monoclonal antibody could not be distinguished from parental viruses with heterogeneous sera, suggesting that they are probably epidemiologically irrelevant. One variant, however, could be distinguished from parental virus with heterogeneous sera. This variant showed a change in sequence at residue 144 of the HA1 polypeptide from glycine in the parent to aspartic acid in the variant. Similar substitutions have been found in naturally occurring variants at this position. These studies suggest that some amino acid substitutions are more important than other for producing viruses with epidemiological potential. Antigenic analysis of naturally occurring H3N2 strains with monoclonal antibodies established that two variants co-circulated in 1968; Hong Kong/1/68 being distinguishable from Aichi/2/68 in at least two antigenic areas. It would appear that there may have been two separate lineages of H3N2 viruses, Hong Kong/1/68 giving rise to variants in England and Aichi/2/68 to variants in USA and Australia.

Amino Acid Sequence↗
PubMed1980

Antigenic variation of influenza A virus nucleoprotein detected with monoclonal antibodies.

Monoclonal antibodies were used to study antigenic variation in the nucleoprotein of influenza A viruses. We found that the nucleoprotein molecule of the WSN/33 strain possesses at least five different determinants. Viruses of other influenza A virus subtypes showed antigenic variation in these nucleoprotein determinants, although changes in only one determinant were detected in H0N1 and animal strains. The nucleoprotein of human strains isolated from 1933 through 1979 could be divided into six groups, based on their reactivities with monoclonal antibodies; these groups did not correlate with any particular hemagglutinin or neuraminidase subtype. Our results indicate that antigenic variation in the nucleoproteins of influenza A viruses proceeds independently of changes in the viral surface antigens and suggest that point mutations and genetic reassortment may account for nucleoprotein variability.

Antibodies, Viral↗
PubMed1979

Antigenic drift in type A influenza virus: peptide mapping and antigenic analysis of A/PR/8/34 (HON1) variants selected with monoclonal antibodies.

Variants of A/PR/8/34 (HON1) influenza virus, having hemagglutinin molecules with probably a single altered antigenic determinant, were isolated by growing the virus in the presence of the monoclonal hybridoma antibody PEG-1. The variants were analyzed by peptide mapping and characterized antigenically by using PEG-1 and four other monoclonal hybridoma antibodies to PR8 hemagglutinin. Peptide maps of the large hemagglutinin polypeptide, HA1, from 8 out of 10 variants showed a single changed peptide. This peptide from two of the variants was analyzed, and in each case a serine residue in the wild-type hemagglutinin was replaced by leucine in the variant. Although these eight variants showed identical peptide maps, one could be discriminated antigenically from the others with one of the hybridomas. (The peptide maps represented about one-third of the HA1 molecule.) Of the other two variants, one gave the same HA1 map as the wild type, but could be distinguished antigenically from wild-type virus by two of the hybridomas. The other was unique, and could be distinguished, both antigenically and by peptide mapping, from the other variants. Since a large number of the variants selected with PEG-1 showed the same peptide change, it is likely that this alteration in amino acid sequence (serine to leucine) was responsible for the inability of the variants to bind PEG-1 monoclonal antibody. We do not know, however, whether the changed amino acids were located within the antigenic sites or whether the change occurred somewhere else in the hemagglutinin molecule and altered the determinants through conformational changes.

Amino Acids↗
PubMed1979

Efficacy of purified influenza subunit vaccines and relation to the major antigenic determinants on the hemagglutinin molecule.

Inactivated whole-virus vaccine of influenza A/Scotland/74 (H3N2) virus containing 700 or 1,400 chick cell-agglutinating (CCA) units, a purified subunit vaccine of equivalent dosage, or placebo were studied in 186 adult volunteers. Placebo was least reactogenic, 1,400-CCA unit whole-virus vaccine was most reactogenic, and others were intermediate. Vaccines were equally antigenic, and delineation of antibody specificities revealed antibody cross-reacting with A/Hong Kong/68 (H3N2) virus in all sera. Antibody specific for A/Hong Kong/68 virus was found in 82% of sera and for A/Scotland/74 virus in 46%. When compared with volunteers given placebo, volunteers given 700 CCA units of subunit or whole-virus vaccine exhibited significant protection against infection with live A/Scotland/74 virus. Infections in vaccinees occurred only in those with low titers of antibody to A/Scotland/74 virus, and this antibody was of the cross-reacting type. Persons with moderate and high levels of antibody resisted infection regardless of the absence or presence of antibody specific for A/Scotland/74 virus. Purified subunit vaccines provide an alternative to whole-virus preparations in primed individuals. Efficacy of vaccines may be dependent on the nature of the antibody response.

Adolescent↗
PubMed1979

Differentiation of the haemagglutinin genes of variant influenza viruses by RNA-RNA hybridization.

The genetic compositions of four antigenic variants of A/Memphis/1/71 (H3N2) influenza virus, which were selected by growth in the presence of monoclonal antibodies against the haemagglutinin, were compared. The results indicate that the mutant haemagglutinin genes can be differentiated by polyacrylamide gel electrophoresis of the double stranded RNA hybrids formed between virion RNA and transcripts isolated from infected cells.

Genes, Viral↗
PubMed1979

Characterization of a new avian influenza virus subtype and proposed designation of this haemagglutinin as Hav10.

The haemagglutinin of A/Dk/alb/60/76, an influenza A virus isolated from feral ducks in Canada, possesses no antigenic relatedness to any of the 16 reference haemagglutinin subtypes. Results of serological tests (HI and double immunodiffusion) with monospecific antisera to the haemagglutinin of this virus indicate that it represents a new avian haemagglutinin subtype. We propose that this haemagglutinin be designated as Hav10 under the current system of nomenclature.

Animals↗
PubMed1979

Geographical distribution of swine (Hsw1N1) and Hong Kong (H3N2) influenza virus variants in pigs in Southeast Asia.

Influenza viruses of the Hsw1N1 and H3N2 subtypes were isolated in Hong Kong from pigs originating from Hong Kong, People's Republic of China (PRC), Singapore, and Taiwan. The H3N2 isolates were from pigs from Hong Kong and PRC, whereas the Hsw1N1 isolates were from pigs from Hong Kong, PRC, Singapore and Taiwan. The hemagglutinins of the H3N2 isolates were similar to those of the earlier A/Hong Kong/1/68 and A/Port Chalmers/1/73 variants from man. The Hsw1N1 isolates were similar to the human A/New Jersey/8/76 virus. These studies extend the geographical range of Hsw1N1 influenza virus and suggest that pigs in southeast Asia, like those in North America, harbor Hsw1N1 influenza viruses. These findings underline the importance of pigs as potential reservoirs for future human pandemics by the continued isolation (in Asia) of H3N2 and Hsw1N1 influenza viruses.

Animals↗