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Biomedical subjects

W G Laver

Publications and source records attributed to W G Laver.

At least 109 records · Page 6Linked to original sources
PubMed1977

The ecology of influenza. Isolation of type 'A' influenza viruses from Australian pelagic birds.

Three different type A influenza viruses have been isolated from pelagic birds nesting on islands of the Great Barrier Reef. One of these, isolated in 1972, was of subtype Hav6Nav5. The other two, which are described in this paper, were isolated in 1975 and belonged to subtypes Hav5Nav2 and Hav3Nav6. Of eight isolates of the latter virus, seven were recovered from cloacal swabs and only one from the trachea.

Animals↗
PubMed1977

Potentiation of the immune response to influenza virus subunit vaccines.

Influenza subunit vaccines are poorly immunogenic in unprimed lower animals and man and methods were sought to potentiate the humoral response. Influenza B intact virus vaccines potentiated the antibody response of hamsters to purified vaccines containing influenza A hemagglutinin and neuraminidase subunits. The levels of anitbody induced were at least as high as those induced by equivalent doses of whole virus. Similarly, intact heterologous influenza A virus vaccine (A/Victoria/3/75 [H3N2]) potentiated the antibody response of hamsters to A/NJ/76 [Hswl NI] subunit vaccines but large doses of intact virus were required. Considerably lower doses of homologous intact A/NJ/76 [Hswl NI] potentiated the antibody response of hamsters and sero-negative people to subunit vaccines. This suggests that future influenza subunit vaccines for use in seronegative people should contain a minimal dose of whole virus vaccine sufficient to potentiate the immune response to the subunits but insufficient to be reactogenic. A synthetic water soluble adjuvant (N-acetyl-muramyl-L-alanyl-D-isoglutamine) was also shown to potentiate the immune response of hamsters to A/NJ/76 [Hswl NI] influenza virus subunit vaccines.

Adjuvants, Immunologic↗
PubMed1976

Influenza virus subunit vaccines. II. Immunogenicity and original antigenic sin in humans.

Subunit vaccines containing hemagglutinin, neuraminidase, and nucleocapsids of A/Port Chalmers/1/73 (H3N2) influenza virus were prepared after treatment of purified virus with ammonium deoxycholate. The immunogenicity of these subunits and the response to the common and specific antigenic determinants on the hemagglutinin subunits were studied in man. The subunits were as immunogenic in man as intact inactivated influenza virus vaccine at an equivalent concentration. Booster doses of antigen did not increase the antibody responses. Intact influenza B virus vaccine did not potentiate the immune response to the type A subunits in man. Volunteers responded differently to the common and specific determinants on the hemagglutinin subunits. The predominant antibody response was to the common or cross-reacting determinants present on hemagglutinins of both A/Hong Kong/1/68 (H3N2) and Port Chalmers/73 virus. Some men who failed to produce specific antibodies to the hemagglutinin of Port Chalmers/73 virus responded to the specific determinants on the Hong Kong/68 hemagglutinin. Higher doses of the subunit vaccines (1,400 chick cell-agglutinating units) did induce antibodies to the specific determinants on the Port Chalmers/73 virus hemagglutinin as well as to the common and specific determinants on Hong Kong/68 influenza virus.

Animals↗
PubMed1976

Antigenic relationships among influenza virua A neuraminidase (N2) antigens by immunodiffusion and postinfection neutralization tests.

The antigenic relationships among the neuraminidases of influenza A strains from 1957 to 1973 were examined by postinfection application of neuraminidase antisera. This procedure causes inhibition of virus spread and apparent neutralization. Neuraminidase (apparent) neutralization and neuraminidase inhibition tests with chicken antisera gave similar results. Neuraminidase inhibition tests were more discriminating than neuraminidase neutralization tests when rabbit and goat antisera were used. Antibody absorption studies revealed that the neuraminidase, like the hemagglutinin, may possess two kinds of antigenic determinants, which can give rise to "common," or "cross-reacting," and "specific" antibodies. "Specific" antibody appears to be more effective in the inhibition of enzyme activity than in the inhibition of virus spread.

Animals↗
PubMed1976

Diversity of the antibody response to the different antigenic determinants on the hemagglutinin subunits of influenza viruses.

Sera from rabbits hyperimmunized with hemagglutinin (HA) subunits isolated from the A/Port Chalmers/73 (H3N2)strain of influenza virus showed great differences in their cross-reactions with different strains of influenza virus. In hemagglutination-inhibition tests, some sera reacted to about the same titer with A/Port Chalmers/73 and A/Hong Kong/68 viruses, suggesting that these two strains were very closely related. Other sera, which reacted to high titer with A/Port Chalmers/73 virus, had only a low titer with the Hong Kong/68 strain, suggesting that the two viruses were distantly related. Evidence suggested that these diverse cross-reactions were due to widely different ratios, in the different sera, of antibodies to the "common" and the "specific" antigenic determinants on the HA subunits. Thus, some rabbits gave a stronger response to the "common" determinants than to the "specific", whereas in others, the reverse seemed to be the case. Sera from human volunteers injected with A/Port Chalmers/73 inactivated or subunit influenza virus vaccines, or from people infected with Port Chalmers/73 virus, contained, in most cases, antibodies predominantly to the "common" antigenic determinants on the HA subunits. These sera reacted to higher titer with Hong Kong/68 virus than with the Port Chalmers/73 strain. Absorption of these sera with Hong Kong/68 virus totally removed all detectable antibody, suggesting that they contained no antibody to the "specific" determinants of Port Chalmers/73 HA. Paradoxically, absorption of the sera with Port Chalmers virus did not remove all antibodies, suggesting that the sera contained antibodies to the "specific" determinants on Hong Kong/68 HA.

Absorption↗
PubMed1974

Inhibition of virus release by antibodies to surface antigens of influenza viruses.

When influenza virus was mixed with antisera to its surface subunits before inoculation of cell cultures, anti-hemagglutinin antibodies neutralized infectivity but anti-neuraminidase did not. When the antisera were added after infection of cell cultures, anti-hemagglutinin and anti-neuraminidase antibodies were equally effective in reducing virus titers in culture fluids. Decreased virus titers were not due to interference of antibody with assay and were not accompanied by a reduction in the synthesis of hemagglutinin and neuraminidase subunits. Both antisera also effectively prevented in vitro virus spread. Inhibition of virus release by neuraminidase antibody appeared unrelated to its antienzyme property. Hydrolysis of N-acetyl neuraminic acid residues of infected host cells proceeded unimpaired in the presence of subunit antisera. Anti-hemagglutinin and anti-neuraminidase antibodies may act to prevent virus release by binding newly formed virus subunits to each other and to anti-genically altered cell membranes.

Adsorption↗
PubMed1973

Influenzavirus neuraminidase and neuraminidase-inhibition test procedures.

The adequate characterization of type A influenzaviruses requires the identification not only of the haemagglutinin but also of the neuraminidase. The neuraminidase-inhibition test, as performed in the two WHO international reference centres for influenza, is described and its use in other laboratories-particularly those collaborating in the WHO programme-is recommended.

Antigens, Viral↗