PESQUISA DE ANTICORPOS NEUTRALIZANTES PARA O VIRÚS DA GRIPE EPIDÊMICA HUMANA TiPO B (LEE), EM PESSOAS NORMAIS, NA CIDADE DE SAO PAULO

Abstract

The first part of this paper deals br'iefly with today's knowledge of human epidemic influenza vírus B in relation to its form, size, behaviour in animais, experimental transmission to human beings, immunity anel epidemiology.  Experiments of neutralizing antibodies against epidemical, influenza vírus B (Lee) were carried on by means of protection proofs in swiss rats with adult's anel children 's sera: the latter were hetween 1 anel 3 years old. The sera were obtained from persons resident in the city of São Paulo, who did not have neither influenza nor a febrile cold in the last mouths. Ali the experimentas made with children's sera were negative, as, in this age (1 to 3 years), the presence of antibodies neutralizing human epidemic influenza vírus B (Lee), was not revealed. The experiments máde with undiluted sera of adults, using the same vírus, gave a positive result o f 43,9%. Conforming to the sera's dilutions the percentage of the positive protection proofs in adults was the following: Pure serum...43,9%; Diluted to....34,1% ... 0,9% ........0,4%........0,4%.......0,0%.Comparing these results with those obtained by the Author in a former study of his, made with human epidemic influenza vírus A (W. S.) under the same technical· conditions and with the same number of sera, and aproximately at the same tim.e, the following results were established in the protection proofs made with adults' sera: Virus "A" (W.S.) : Positive proofs............82,9%. Negative proofs......17,1% .Vírus "B" (Lee) : Positive proofs..........43,9%. Negative proofs..........56,1%. It is to be pointed out that only results obtained with. pure serum have been taken into consideration. The higher grade of incidence of neutralizing antibodies against human epidemic influenza vírus A than against vírus B leads to the presumption that in São Paulo influenza A is more common than. influenza B; although also influenza B must have been present in this city. This assertion is substantiated by the presence of antibodies against. vints H (Lee) which fact has been the object of this paper.