Ether-treated, subunit Hsw1N1 influenza vaccines: response of immunologically primed subjects to two antigenic variants.

Two bivalent, ether-treated, subunit influenza vaccines were compared in adults greater than or equal to 45 years old. Both vaccines contained 200 chick cell-agglutinating (CCA) units of A/Victoria/3/75 antigen/dose. The Hsw1N1 components, also at a level of 200 CCA units/dose and designated A/Shope and A/X-53, were antigenically representative of the A/swine/1976/31 and A/New Jersey/8/76 viruses, respectively.

Automated procedure for measuring antigenicity of extracted and intact influenza virus.

An automated serum-blocking (S-B) technique was developed in an attempt to find an in vitro test for the determination of the antigenicity of extracted influenza vaccines. The S-B test depends on the ability of an antigen to combine with (or block) specific (in this case, hemagglutination-inhibiting) antibodies. After mixing the test virus with a constant amount of specific antiserum and hemagglutinating virus in an Auto Analyzer, chicken erythrocytes were pumped into the system and the mixture was incubated by passing through coils.

Induction of an inhibitor of influenza virus hemagglutination by treatment of serum with periodate.

Serum is commonly treated with potassium periodate to destroy nonspecific inhibitors of influenza virus hemagglutination. We have observed, however, that such treatment of serum without pre-existing inhibitor produced high titers of inhibitor against certain strains of influenza virus. Inhibitor was induced in the serum from several different animal species but not in hamster or mouse serum.

Preservation of influenza virus infectivity by lyophilization.

A method of lyophilizing influenza virus in allantoic fluid with retention of high-titer of egg infectivity is described. Five strains of virus were lyophilized, and all were much more stable than fluid virus preparations, retaining 2 to 3 logs of infectivity after storage at 37 C for 60 to 95 days. Statistical analysis of an accelerated storage test by extrapolation of viral degradation indicates that the lyophilized viruses are stable indefinitely at or below room temperature.