[The analysis of bro genes of GD isolate of Bombyx mori nucleopolyhedrovirus].
BmNPV GD isolate from China was plaque-purified and four bro genes were cloned termed as bro-a,b,c,d. The obtained sequences were aligned to the related sequences in GenBank and the BmNPV CQ1 isolate preserved in our laboratory. Compared with genome sequences of BmNPV T3 isolate, bro genes of GD isolate housed insertion and deletion, and the changes of amino acid mainly occured at the N terminal of corresponding protein. The phylogenetic analysis of bro genes indicated that GD bro-d gene belongs to subgroup A together with T3, CQ1 bro-d and SC7 bro- III; GD bro-a, c genes belong to subgroup B together with T3, CQ1 bro-a, c and SC7 bro-II; GD bro-b gene belongs to subgroup C together with T3, CQ1 bro-b, e and SC7 bro-I. The evolutionary relationship of bro genes showed vague relevance to their geographical location. The distribution character of bro genes in four BmNPV isolates is coincidence with the KANG's theory that the bro-d plays an irreplaceable functional role(s) during viral replication, while bro-a and bro-c functionally complement each other. Meanwhile, we postulate that 3 bro genes in SC7 isolate is probable the most simple form of bro genes.