T-CELL RESPONSIVENESS TO LCMV SEGREGATES AS A SINGLE-LOCUS IN CROSSESBETWEEN BALB CA AND C.B-17 MICE - EVIDENCE FOR REGULATION BY A GENE OUTSIDE THE IGH REGION/

The course of systemic infection with lymphocytic choriomeningitis vir us (LCMV) was studied in BALB/cA and C.B-17 mouse strains differing in the immunoglobulin heavy chain region (Igh). Susceptibility to intrac erebral infection and the ability to clear the virus differed signific antly between these presumably congenic strains, suggesting that a gen e in the Igh region might influence the course of this infection. A di fference in virus spread prior to appearance of the immune response co uld not explain the observed differences. On the other hand, the diffe rences in course of infection correlated with a difference in virus-sp ecific T-cell responsiveness measured in terms of virus-specific cytot oxicity in vitro and delayed-type hypersensitivity in vivo. Analysis o f F1, BC1 and F2 progeny showed that differential T-cell responsivenes s was influenced by a single gene or gene complex; however, no linkage was found between this locus and the Igh-C region. Taken together, th ese results indicate that an additional, and previously unknown, genet ic difference exists between these two mouse strains, and that the inv olved locus carries a gene which significantly affects T-cell responsi veness to LCMV.