Medicion de los anticuerpos contra el virus de la inmunodeficiencia humana: estudio internacional en colaboración para evaluar los sueros de referencia de la OMS

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

IgM responses to hepatitis-A virus and hepatitis-B core antigen in acute and chronic liver disease in Malawi; possible role of non-A; non-B; hepatitis

Of 33 patients with acute hepatitis in Malawi; 21 had infection by hepatitis-B virus (HBV); five by hepatitis-A virus (HAV) and seven; who had no markers of current HBV or HAV infections; were probably infected by the agent(s) of non-A; non-B; hepatitis. 87 of 88 sera from persons without liver disease contained antibody to HAV and 49 antibody to hepatitis-B surface antigen (anti-HBs) (six were positive for hepatitis-B surface antigen). The diagnosis of recent infection by HAV was made by detecting HAV-specific IGM in single serum samples and; although such tests showed that HAV caused acute hepatitis; its absence in patients with chronic liver disease suggests that; unlike HBV; infection by HAV does not play a role in chronic liver disease in Malawi. Anti-hepatis-B core antigen (anti-HBc)-specific IgM was detected in 19 of 21 patients with acute HBV infection; in three of five HbsAg-positive patients with cirrhosis; but in none of five Hbs Ag-positive patients with hepatoma