MYELOID DEPRESSION FOLLOWS INFECTION OF SUSCEPTIBLE NEWBORN MICE WITHTHE PARVOVIRUS MINUTE VIRUS OF MICE (STRAIN-I)

The in vivo myelosuppressive capacity of strain i of the parvovirus mi nute virus of mice (MVMi) was investigated in newborn BALB/c mice inoc ulated with a lethal intranasal dose. MVMi infection reached maximum l evels of DNA synthesis and infectious titers in lymphohemopoietic orga ns at 4 to 6 days postinoculation and was restricted by an early neutr alizing humoral immune response. After viral control (by 10 days posti noculation), a significant decrease in femoral and splenic cellularity , as well as in granulocyte-macrophage colony-forming unit and erythro id burst-forming unit hemopoietic progenitors, was observed in most in oculated animals. This delayed myeloid depression, although it may be not a major cause of the lethality of the infection, implies indirect pathogenic mechanisms induced by MVMi infection in a susceptible host.