J.S. Oxford

Influenza A (H1N1) vaccine efficacy in animal models is influenced by two amino acid substitutions in the hemagglutinin molecule

The immunogenicity and protective efficacy of formalin-inactivated vaccines prepared from influenza A (H1N1) viruses grown in MDCK cells and in eggs was compared in animal models. The A/Chr/157/83 virus grown in MDCK cells (157M) differed by two amino acid substitutions in the HA molecule from the corresponding virus grown in eggs (157E) and the two viruses could be distinguished antigenically by monoclonal and polyclonal antibodies. Following two intramuscular injections of vaccine in ferrets, guinea pigs, and hamsters, both vaccines were equally immunogenic when antibody was analyzed by hemagglutination inhibition using homologous virus. However, single radial hemolysis analysis following antibody cross-adsorption showed that antibody stimulated by 157E vaccine was exclusively strain specific whereas that produced by the 157M vaccine was more broadly reactive. When immunized hamsters were challenged with virus cultivated on mammalian (MDCK) cells, the homologous vaccine induced a higher degree of protection than the corresponding egg-grown vaccine.

Evidence for antigenic variation in influenza A nucleoprotein.

Abstract Nucleoprotein (NP) antigens isolated from sodium sarcosyl detergent-disrupted influenza A virus particles by cellulose acetate electrophoresis were used to prepare specific immune sera. Antigenic analysis of the nucleoproteins by immuno-double-diffusion and antibody absorption tests revealed antigenic differences in the nucleoprotein antigens of human A/PR8/34 (HON1) virus and viruses of the Hong Kong (H3N2) subtype. The nucleoprotein antigens of avian A/duck/Ukraine/1/63 (Hav7Neg2) and A/swine/Iowa/15/30 (Hsw1Nl) viruses resembled more closely the NP of A/PR8/34 virus than the NP of human H3N2 strains. Antigenic analysis of recombinant strains prepared from A/PR8/34 and H3N2 parent viruses indicated that the parental origin of the NP antigens could be clearly identified. Identification of the nucleoproteins of parental and recombinant influenza A viruses by migration rate analysis of NP polypeptides and RNA genes by electrophoresis on polyacrylamide gels gave results which correlated with the antigenic characterization of their NP antigens. The findings suggested that antigenic “drift” occurs in the nucleoproteins of human influenza A viruses.

THERAPEUTIC EFFECT OF 1-ADAMANTANAMINE HYDROCHLORIDE IN NATURALLY OCCURRING INFLUENZA A2/HONG KONG INFECTION: A Controlled Double-blind Study

Abstract The therapeutic activity of 1-adamant-anamine hydrochloride (amantadine) was investigated in a double-blind study of patients with clinically and serologically confirmed influenza A 2 /Hong Kong/68 infections who continued to live in their normal domestic environment. There was a significant reduction (P

Naturally Occurring Temperature-sensitive Influenza A Viruses of the H1N1 and H3N2 Subtypes

Seventeen of twenty-six influenza A virus isolates of the H1N1 antigenic subtype and two of eleven H3N2 virus isolates from the 1977-78 season exhibited a ts phenotype, were restricted in plaquing in MDCK cells at 38.5 degrees C compared to 34 degrees C and appeared to be naturally occurring ts mutants. The cut-off temperature for two such ts H1N1 virus isolates was established as 38 degrees C. The ts viruses were as thermostable as non-ts isolates and no complementation was detected between the twelve ts viruses tested. Cloning studies with an H1N1 virus isolate with minimal ts properties indicated the presence of a mixed population of ts+ and ts particles. Analysis of seven recombinants of A/HK/117/77(N1N1) virus indicated that the ts lesion(s) was not located in the NA or HA proteins.

Intratypic electrophoretic variation of structural and non-structural polypeptides of human influenza A viruses.

Intratypic electrophoretic mobility differences in high resolution SDS-polyacrylamide gels were detected between corresponding matrix (M) proteins, nucleoproteins (NP), haemagglutinin (HA) and the non-structural polypeptides NS1 and NS2 induced in Vero cells by human influenza A viruses of the antigenic subtypes H1N1 and H3N2. Such phenotypic differences were distinguishable in both H1N1 and H3N2 viruses isolated in single school and city outbreaks. Additional intratypic variation was detected in the biological property of virus plaquing in MDCK cells. Although the biochemical basis is not established, phenotypic variation could represent an additional factor influencing the epidemiology of influenza A viruses.

Early interactions between animal viruses and the host cell: relevance to viral vaccines

Abstract Viral recognition of specific receptors in the host cell plasma membrane is the first step in virus infection. Attachment is followed by a redistribution or capping of virus particles on the cell surface which may play a role in the uptake process. Certain viruses penetrate the plasma membrane directly but many, both enveloped and non-enveloped viruses, are endocytosed at coated pits and subsequently pass into endosomes. The low pH environment of the endosome facilitates passage of the viral genome into the cytoplasm. For some viruses the mechanism of membrane penetration is now known to be linked to a pH-mediated conformational change in external virion proteins. As a consequence of infection there are alterations in the permeability of the plasma membrane which may contribute to cellular damage. Recent advances in the understanding of these processes are reviewed and their relevance to the development of new strategies for vaccines emphasised.