Viral hepatitis and immunoprophylaxis

: Today we distinguish 4 forms of viral hepatitis: hepatitis A, hepatitis B, hepatitis non-A, non-B and hepatitis occurring in the course of other viral diseases. The viruses of hepatitis A and hepatitis B have been identified but the agent(s) of hepatitis non-A, non-B remain unknown. Inoculation of normal pooled human immunoglobulin provides passive immunity for 2-3 months against hepatitis A but not against hepatitis B or hepatitis non-A, non-B. For passive protection against hepatitis B a special immunoglobulin with a high anti-HBs titer must be used whereas the protection against hepatitis non-A, non-B with immunoglobulin is uncertain. Live attenuated and noninfectious polypeptide vaccines for active immunisation against hepatitis A are currently developed and first clinical trials have begun with the live attenuated vaccine. A vaccine consisting of noninfectious highly purified HBsAg derived from the plasma of HBV carriers is in general use since two years and has proved safe and highly effective and vaccines are now developed from HBsAg obtained through molecular cloning of the HBsAg genome in plasmids and expression of the genome with HBsAg production in yeast cells. First clinical studies with this vaccine are encouraging and these as well as purely synthetic vaccines will in time replace the currently used vaccines. No vaccines could be developed so far against hepatitis non-A, non-B because the agent(s) of this disease are unknown.