Abstract: Dendrolimus punctatus cytoplasmic polyhedrosis virus strain Hunan (DpCPV-HN) was cloned in vivo and identified as a type 1 cypovirus. Fourth-or 5th day posthatching F₁ and F₂ silkworms from an generation F₁ that had previously been infected by DpCPV-HN, and two other type 1 cypoviruses from Bombyx mori(BmCPV-1) and D. punctatus(DpCPV-HN) were selected for the infection test. The results indicate that the breed of B. mori tested in this study was very sensitive to BmCPV-1, and could also be infected by DpCPV-HN. Based on the accumulative total mortalities of F₁ and F₂ generations of B. mori infected by DpCPV-HN over 28 days post-infection，the 50% lethal doses (LD50) of DpCPV-HN of F₁ and F₂ generations were 885 and 18 CPBs respectively. Obviously, the F₂ silkworm larvae from DpCPV infected generation F₁ were more sensitive to DpCPV-HN than those of the F₁ generation. However, the sensitivity of the F₂ generation to DpCPV-HN was still inferior to that of the F₁ to BmCPV-1. To some degree, the ratio of cocoons，ratio of pupae，ratio of moths to pupae, cocoon weight, cocoon shell weight, ratio of cocoon shell weight, and number of eggs from single female moths of the F₁ and F₂ generations were affected after infection by DpCPV-HN. The correlations between cocoon weight, cocoon shell weight, ratio of cocoon shell weight，number of eggs from single female moths of silkworms and inoculation doses of DpCPVHN were not obvious.

Key words: DpCPV-HN, BmCPV-1, Bombyx mori, sensitivity, in vivo cloning