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Biomedical subjects

W G Laver

Publications and source records attributed to W G Laver.

At least 127 records · Page 7Linked to original sources
PubMed1973

Characterization and ecology of a type A influenzavirus isolated from a sheawater.

An influenzavirus isolated from a shearwater bird nesting on Tryon Island on the Australian Great Barrier Reef in 1971 has been more extensively characterized. Haemagglutinin subunits were isolated from the shearwater virus and from the antigenically related avian influenzaviruses A/turkey/Mass./65 (Hav6N2) and A/duck/Penn./69 (Hav6N1). Maps of the tryptic peptides from the heavy polypeptides (HA1) of the haemagglutinin subunits of the three viruses showed a number of differences, but peptide maps of the light polypeptides (HA2) were almost identical, suggesting that these had almost the same amino acid sequence. Extensive tests confirmed that the neuraminidase of the shearwater virus was not related antigenically to any known neuraminidase. The sera collected from pelagic birds nesting on islands in the Capricorn-Bunker group in 1970 were devoid of any antibodies to the shearwater virus, while a high proportion of the sera collected from birds on the same islands in 1972 (one year after the isolation of the shearwater virus) had antibodies to the haemagglutinin and neuraminidase of the shearwater virus, some to a high titre. Thus, the shearwater virus appeared to have only recently been introduced into the area from where it was isolated.

Animals↗
PubMed1972

The origin of pandemic influenza.

Serological tests, using antisera specific to the surface subunits of the viruses (e.g., antisera to the haemagglutinin subunits devoid of any antineuraminidase or anti-host antigen activity) showed that the haemagglutinin subunits of the Hong Kong virus were, immunologically, distinct from the subunits of the preceding A/Asian strains. On the other hand, the neuraminidase subunits of the Hong Kong virus are related to those of the A/Asian strains. The haemagglutinin subunits of influenzaviruses are composed of two pairs of light and heavy polypeptide chains and it was found that the amino acid sequence of the light and heavy chains from the haemagglutinin subunits of the Hong Kong virus differed remarkably from those of the preceding A/Asian strains. These findings suggest that Hong Kong virus did not arise by mutation from a pre-existing human strain and that it probably arose by the selection of a genetic recombinant in a partially immune population. It is postulated that the recombinant was formed as the result of the mixed infection of an animal or bird with an animal or avian influenzavirus and a human A/Asian strain. The animal (or avian) virus could have donated the haemagglutinin subunits of A/Hong Kong/1/68 virus and the neuraminidase subunits could have come from the human A/Asian strain.

Antigens, Viral↗
PubMed1972

Antibodies to human influenzavirus neuraminidase (the A-Asian-57 H2N2 strain) in sera from Australian pelagic birds.

Sera collected from Australian pelagic birds specifically inhibited the neuraminidase of the Asian/57 (H2N2) strain of human influenzavirus. Neuraminidase inhibition titres of some sera were high and the avidity of the inhibitor was comparable to that of specific antibody. The neuraminidase of A/Hong Kong/1/68 (H3N2), which has undergone considerable antigenic drift in man since 1957, was inhibited to a lesser extent by the bird sera, while the neuraminidases of the A/BEL/42 (H0N1) and A/FM/1/47 (H1N1) strains were not inhibited at all. The inhibitor could be removed from the sera by adsorption with A/57 virus particles, but not by particles of A/BEL or A/FM1 viruses. These results suggested that the inhibitor in the bird sera was specific antibody. The antibodies to A/57 neuraminidase were found in sera from wedge-tailed shearwaters (Puffinus pacificus) and noddy terns (Anous minutus) nesting on islands off the north-east coast of Australia. They were not found in sera from bridled terns (Sterna anaetheta) or brown gannets (Sula leucogaster) nesting on the same islands. Antibodies to A/57 neuraminidase were also detected in sera from short-tailed shearwaters (Puffinus tenuirostris), which migrate around the Pacific Ocean, suggesting that these birds may be responsible for bringing avian influenzaviruses from areas in the Northern Hemisphere into Australian coastal waters.

Animals↗
PubMed1970

Antibodies to influenza viruses (including the human A2-Asian-57 strain) in sera from Australian shearwaters (Puffinus pacificus).

Sera were collected from 320 shearwaters (Puffinus pacificus chlororhynchus) nesting on two islands off the east coast of northern Australia in December 1969. About 10% of these sera specifically inhibited the neuraminidase of the 1957 strain of human influenza (A2/Asian/57), some to high titre.The neuraminidase of A2/Hong Kong/68, which has shown considerable drift in man since 1957, was inhibited to a lesser extent by the shearwater sera while the neuraminidase of influenza A0 (Bel strain) was not inhibited at all. The sera showed no evidence of short-lived antibody to the internal antigen of influenza type A, suggesting that the birds had been infected a considerable time previously with an influenza virus possessing neuraminidase identical to that of the virus causing the human 1957 Asian pandemic. On the other hand, about 10% of the sera from one of the islands was found to be positive in immunodiffusion tests with influenza type A soluble internal antigen (ribonucleoprotein), suggesting that another, much more recent, epidemic of avian influenza had occurred on this island only. The surface antigens of the virus responsible for this epidemic have not so far been identified.Observations suggest that avian influenza may be common in wild birds and the finding of antibody to an antigen of human influenza virus in shearwaters is consistent with the idea that human influenza pandemics may originate from avian or animal reservoirs.

Animals↗