Immunopathology of Mouse Hepatitis Virus Type 3 Infection

Abstract

Humoral and cell-mediated immune responses were studied in resistant and susceptible strains of mice infected with mouse hepatitis virus type III (MHV₃). Virus was maintained by regular passages in susceptible DBA/2 mice and assayed in DBA/2 mice by LD₅₀ determination. Normal resistant A strain mice were able to clear the virus from liver, brain, and serum within 7 days after infection. No neutralizing antibody was found. Transfer of serum from immunized A strain mice was not effective in protecting susceptible DBA/2 mice against challenge with virus. In A strain animals resistance to MHV₃ developed rapidly during the 3rd week of life. During the period of susceptibility, newborns were protected neither by transplacental passages of anti-MHV₃ antibodies nor by injection of “educated” thymus cells. These results suggest that the development of resistance to MHV₃ infection in mice cannot be explained solely on the basis of humoral or cell-mediated immunity.