Recombination and Transmission Studies with Influenza Virus.
Annual progress rept. 1 Jul 68-31 May 69,
MOUNT SINAI SCHOOL OF MEDICINE NEW YORK
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Studies initiated in 1968 of the independent antigenic drift of neuraminidase and hemagglutinin antigens have been continued and have coincided with an investigation of the new Hong Kong virus. These studies, employing specially fabricated recombinant viruses in which neuraminidase and hemagglutinin antigens were segregated by hybridization with AoNWS, have shown an independent and non co-varying mutation in these antigens during the 1957-68 period. Of great interest is the discovery that cross reactivity of the Hong Kong strain with the A2 family of strains occurs only through their common neuraminidase antigen. Cross reactivity in the hemagglutinin antigens is not demonstrable when these antigens are segregated in recombinants even when exquisitely sensitive tests such as plaque inhibition are employed. Studies of the comparative efficacy of intranasal versus intraperitoneal inoculation of mice with inactivated influenza viruses have demonstrated that in this system a single intranasal inoculation is not sufficient to induce protection, although it may prime the animal or boost him to an immune state. Further evidence has been obtained that viral transmissibility is a separate genetic attribute from other factors in virulence. An important practical achievement with direct potential application in the military has been the hybridization of Hong Kong and PR8 viruses to produce a high yielding vaccine virusX-31 which has actually been introduced into commercial production and is available now for field testing.