Effect of the host cells in the crossed neutralization reactions between Junín and Tacaribe viruses

: It has been previously reported that guinea pigs inoculated with Tacaribe virus grown in suckling mouse brain, develop specific anti-Junin neutralizing antibodies (NA) after 45 days of infection and a typical secondary response after Junin virus challenge. Since in these experiments both viruses were grown in suckling mouse brain doubt was raised about the specificity of NA, considering the possibility that they were raised against host-cell antigens. In order to test this interpretation the following experiments were performed. Stocks of Tacaribe and Junin viruses were prepared in sucking mouse brain, in monkey kidney cells (Vero) and in rabbit kidney cells (RK13). Different groups of guinea-pigs were inoculated with 1000 TC ID50 from each stock of Tacaribe virus. The animals were challenged on day 66 p.i. with 1000 LD50 of Junin virus grown in suckling mouse brain. Animals were bled at 30, 60 and 80 days after Tacaribe virus infection and sera were assayed in neutralization tests against Tacaribe and Junin viruses grown in Vero or RK13 cells or suckling mouse brain. Specific NA against Junin virus were found in all sera on day 60 post Tacaribe infection, discarding the possibility that the antibodies were not specifically directed against virus antigens. However, it was observed that the antibody titers were higher when neutralization was performed using immune sera prepared with virus grown in the host used for virus antigen. These results suggest that during the process of budding, viruses recruit cellular antigens which enhance the immune response.(ABSTRACT TRUNCATED AT 250 WORDS)