The in vitro expression patterns of individual type I interferon genes in Newcastle disease virus infected murine splenocytes and fibroblasts

Murine type I interferon levels present in mice sera following Newcastle disease virus infections are influenced by the If-1 locus. Sera interferon levels in C57BL/6 mice (If-1(h) allele) are 10- to 15-fold higher than in BALB/c mice (If-1(l) allele). The B6.C-H-28(c) strain, which carries BALB/c If-1(l) allele on C57BL/6 genomic background, has low interferon levels in sera. This study examined the expression of interferon alpha 1, alpha 4, alpha 5, alpha 6, alpha 9 and beta mRNAs at 7 hr after Newcastle disease virus infection of primary cells (splenocytes and mouse embryo fibroblasts) from C57BL/6, B6.C-H-28(c) and BALB/c mouse genotypes. Total RNA from these cells was reverse transcribed and all known type I interferon subtypes were amplified. The products were identified By differential hybridization to a panel of subtype specific oligonucleotides. The results show that the pattern of interferon subtypes examined in splenocytes did not differ between If-1(h) and If-1(l) allele carrying C57BL mice. However, when the genotype was different (BALB/c splenocytes) the pattern of type I interferon mRNAs seen was altered. This genotype-dependent expression was also seen in Newcastle disease virus infected fibroblasts. Within a given mouse strain, there were also differences in the subtype response patterns detected in fibroblasts compared with those seen in splenocytes. In conclusion, the present study indicates that mouse genotype appears to be a major determinant of the subtype response pattern seen and tissue specific pattern differences are present within a given mouse genotype.