Strain-specific selection of genome segments in avian reovirus coinfections

To determine whether selection ofgenome segments in coinfections i strain-specific, hicken embryo fibro-blasts were coinfected with avian reovirus strain 883 and one of three other avian reovirus strains (176, S1133 and 81-5). Viral progeny from each coinfection (883x176, 883xS1133 or 883x81-5) was serially passaged at a low m.o.i. The electropherotypes of the coinfection progeny and those of the plaque-derived clones obtained from passages 1 and 20 were analysed. Two 883 segments (M2 and $2) were found to be selected in the 883x176 coinfection, three 883 seg-ments (M2, M3 and $2) in the 883 x S1133 coinfection, and only one 883 segment (M3) in the 883x81-5 coinfection, i.e. different 883 genome segments were selected in the three coinfections. It was, therefore, concluded that selection of genome segments in a coinfection of a given cell line is virus strain-specific. The selection of genome segments in coinfections was shown to be due to enhanced infectivity of the reassortants hat were formed in the coinfections. In addition, defective interfering particles that lack the S 1 segment were identified in the 883x81-5 coinfection progeny following serial passage. Selection of genome segment(s) in coinfections as described herein may have potential importance on the effect and production of divalent or multivalent vaccines