Subject(s)
Poliomyelitis , Poliovirus Vaccine, Inactivated , Immunization , Poliovirus , Review , CertificationSubject(s)
Poliomyelitis , Poliovirus Vaccine, Inactivated , Immunization , Poliovirus , Review , CertificationABSTRACT
Los estudios efectuados señalan que los desplazamientos antigénicos en el virus A de influenza aparecen según un ciclo que se repite y se va renovando. En 1973 se diagnosticó la reaparición de la cepa de influenza porcina aislada en Fort Dix, Nueva Jersey, similar a que desató la pandemia de 1918 (AU)
Subject(s)
Influenza A virus/isolation & purification , Epidemiology/trends , United States/epidemiologyABSTRACT
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)
Subject(s)
Antigens, Viral , Orthomyxoviridae/immunologyABSTRACT
Marburg virus disease, which produced 20 per cent mortality when it first occured during 1967 in Germany and Yugoslavia, recently appeared again in South Africa. The source of the first outbreak was monkeys shipped from Africa; the origin of the second episode is unclear. Because distribution of the virus in nature is unknown, its threat to man cannot be readily determined. Differential laboratory diagnoses of hemorrhagic fevers should be encouraged in order to learn more about the epidemiology of these diseases and to better assess the risks which their etiologic agents may pose for attending medical personnel (Au)
Subject(s)
Marburgvirus , Marburgvirus/pathogenicity , Germany, West , South Africa , YugoslaviaABSTRACT
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)
