RESUMO
Two preparations of human sera, one reactive against human immunodeficiency virus (HIV) and the other unreactive, were evaluated as potential international reference reagents (IRR) in an international collaborative study. Twenty-one laboratories participated and tested these and five other human sera which were found to range from highly reactive to unreactive. The proposed "positive" IRR was found to react strongly in all immunoassays and gave all the expected bands in immunoblot systems using HTLV-III, LAV-I or similar virus strains as antigens. The "unreactive" serum was judged to be negative by ELISA and immunoblots. The end-points determined by ELISAs varied considerably between laboratories, even between those using the same commercial kit. This variation was reduced somewhat when the reactivities of the samples were expressed relative to the proposed IRR
Assuntos
Anticorpos Antivirais/análise , Ensaio de Imunoadsorção Enzimática , HIV , Cooperação Internacional , Imunoensaio/métodos , Valores de Referência , Organização Mundial da SaúdeRESUMO
Influenza viruses have two surface antigens, the glycoprotein structures hemagglutinin (HA) and neuraminidase (NA). Antibodies to each of these are associated with immunity, but the structures themselves are antigenically variable. When an antigenic change is gradual over time it is referred to as a drift, while a sudden complete or major change in either or both antigens is termed a shift. The mechanism of antigenic drift is usually attributed to selection of preexisting mutants by pressure from increasing immunity in the human population. The mechanism of antigenic shift is less clear, but one tentative hypothesis is that shifts arise from mammalian or avian reservoirs, or through genetic recombination of human and animal influenza strains (Au)
Assuntos
Antígenos Virais , OrthomyxoviridaeRESUMO
Outbreaks of influenza due to the virus A/Hong Kong/1/68 (H3N2) began in 1968 and are still occurring. The haemagglutinin of this virus is different from that of the A/Singapore/1/57 virus (the "Asian" strain) but the neuraminidase antigens are the same. Between 1968 and 1971 only minor antigenic "drift" in the haemagglutinin was noted, but in recent months 2 isolates have been identified in which considerable "drift" has occurred in the haemagglutinin and in the neuraminidase antigens. One, A/Hong Kong/5/72 (H3N2), was first detected in outbreaks in Hong Kong between November 1971 and January 1972 and was predominant there and in Korea but did not become widely disseminated. The second strain, A/England/42/72 (H3N2), has been isolated in winter outbreaks in the southern hemisphere and now appears to be the predominant strain in the northern hemisphere. The characteristics of the strains are described.
Assuntos
Antígenos Virais , Genética Microbiana , Imunogenética , Orthomyxoviridae/imunologia , África , Ásia , Austrália , Europa (Continente) , Testes de Inibição da Hemaglutinação , Humanos , Imunodifusão , Influenza Humana/epidemiologia , Neuraminidase/antagonistas & inibidores , América do Norte , América do SulRESUMO
A longitudinal study of illness and prevalence of enteroviruses was carried out in a Trinidad residential nursery. 92 enteroviruses (46 strains of Coxsackie B virus and 46 of poliovirus) were recovered from 233 faecal specimens (39.5 percent). The percentage of children who excreted viruses at any one time rose from 48 percent to 90 percent, being related to the number of specimens examined from each child. Apparent interference between Coxsackie B viruses and polioviruses was observed and the significance of this in relation to poliovirus vaccination is discussed. (AU)
Assuntos
Humanos , Pré-Escolar , Masculino , Feminino , Infecções por Enterovirus/epidemiologia , Enterovirus/isolamento & purificação , Poliovirus/isolamento & purificação , Fezes/microbiologia , Trinidad e Tobago , Interferência ViralRESUMO
Two preparations of human sera, one reactive against human immunodeficiency virus (HIV) and the other unreactive, were evaluated as potential international reference reagents (IRR) in an international collaborative study. Twenty-one laboratories participated and tested these and five other human sera which were found to range from highly reactive to unreactive. The proposed "positive" IRR was found to react strongly in all immunoassays and gave all the expected bands in immunoblot systems using HTLV-III, LAV-I or similar virus strains as antigens. The "unreactive" serum was judged to be negative by ELISA and immunoblots. The end-points determined by ELISAs varied considerably between laboratories, even between those using the same commercial kit. This variation was reduced somewhat when the reactivities of the samples were expressed relative to the proposed IRR