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The influence of acidic pH on the infectivity and neuraminidase activity of human, equine and avian type A influenza virus strains has been studied. Following exposure to pH 3 human and equine strains lost their infectivity completely, whereas all investigated strains of the subtypes Hav6N2 and Hav7Neq2 retained a certain amount of infectivity. In contrast(More)
Anal virus shedding and stimulation of the immune response were observed in ferrets after oral and rectal administration of influenza A/Hongkong/1/68 (H3N2) virus. Despite of the low pH in the stomach, the virus had reached the intestines after oral administration and was found in high concentration in faeces and in mucosal cells lining the colon. Using(More)
Candidate cell substrates for vaccine production must be controlled for the absence of tumorigenic activities. This test is done in most laboratories by heterotransplantation of living cells in Syrian hamsters either subcutaneously into newborns or into the cheek-pouch tissue of older ones. The necessity of a long observation period and high rate of(More)
Evaluating the current stage and future trends of WHO's Expanded Programme on Immunization (EPI), conclusions for national immunization strategies have been considered. The global eradication of poliomyelitis is an important target. In 1988, an Immunization Advisory Group of the Ministry of Health has been founded. Recommendations regarding the update of(More)