An ELISA was developed for detection of antibodies to GB virus C (GBV-C) using a recombinant E2 protein expressed in CHO cells. Seroconversion to anti-E2 positivity was noted among several persons infected with GBV-C RNA-positive blood through transfusion. Of 6 blood recipients infected by GBV-C RNA-positive donors, 4 (67%) became anti-E2 positive and cleared their viremia. Thus, anti-E2 seroconversion is associated with viral clearance. The prevalence of antibodies to E2 was relatively low (3.0%-8.1%) in volunteer blood donors but was higher in several other groups, including plasmapheresis donors (34.0%), intravenous drug users (85.2%), and West African subjects (13.3%), all of whom tested negative by GBV-C reverse-transcription polymerase chain reaction (RT-PCR). These data demonstrate that testing for anti-E2 should greatly extend the ability of RT-PCR to define the epidemiology and clinical significance of GBV-C.

Some 33 to 50 percent of cases of hepatitis B that could be transmitted by transfusion of blood from HBsAg-negative donors are prevented by anti-HBc screening. Anti-HBc-positive donors unequivocally positive for anti-HBs should be considered noninfectious for HBV and should be allowed to donate. Anti-HBc screening of paid plasmapheresis donors, supplemented by anti-HBs testing, would reduce the amount of HBV to be processed by virus inactivation and increase the content of anti-HBs in plasma pools.

To evaluate the incidence of post-transfusion hepatitis and factors influencing its occurrence, the Transfusion-Transmitted Viruses Study prospectively followed 1513 transfusion recipients from 1974 through 1979. The attack rate for non-A,non-B hepatitis was 10 per cent. The incidence of hepatitis was directly related to the alanine aminotransferase (ALT) level in blood donors. In recipients of multiple transfusions of blood that had no donor-ALT level above 29 IU per liter the attack rate was 6 per cent or less; at higher donor-ALT levels the attack rate increased progressively, reaching 45 per cent in recipients of units with an ALT of 60 IU or greater. A similar relation was observed among recipients of single units of blood. Moreover, hepatitis developed in 10 of 11 recipients of two units with an ALT level of 45 IU or greater. These data indicate that screening blood for ALT levels would reduce the incidence of non-A,non-B post-transfusion hepatitis.

Objective-To investigate the possible interference with acute hepatitis B virus infection by coinfection with hepatitis C virus.Design-Analysis of stored sera collected for transfusion transmitted viruses study in 1970s.Setting 479-2465 IUl1) and biphasic in patients with combined acute infection (no value >380 IU/1; p=0 0025). Four coinfected recipients developed chronic hepatitis C virus infection. The fifth patient was followed for only four months.Conclusions-Acute coinfection with hepatitis C virus and hepatitis B virus inhibits hepatitis B virus infection in humans, and onset of hepatitis B may reduce the severity of hepatitis C virus infection but not frequency of chronicity. Alanine aminotransferase concentration showed a biphasic pattern in dual infection.

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