Studies on the Generation-to-Generation Transmission of Cytoplasmic Polyhedrosis Virus and the Effect of Their Activation on the Induction in the Next Generation in the Silkworm, Bombyx mori L.

Virus의 경란전염이 차대의 잠작에 미치는 영향에 관한 연구

Many of studies on the transovarial transmission of occult virus and their activation due to various stresses such as cold or heat treatment, chemical feeding, and nutritional deficiency, etc., in the silkworm, Bombyx mori L. have been made, but any attempts have been not made to control virus diseases by detection of the occult virus-carried moths in the production of silkworm egg of hybrids, because of difficulty to detect occult virus in any stage. Therefore, it may be worth while to disclose whether a sublethal infection of the moths from which active virus are detectable, has the same level of induction rate as that of occult virus activation, thus to apply its results for the reduction of the occurence of virus diseases in silkworm rearing. For these purposes, the following experiment was conducted as one of preliminary steps. In this study, investigations on the generation-to-generation transmission of occult virus and a sublethal infection, and the role of chromosomal gene of the host, Jam 103 and Jam 104 in the Previous generation, and Jam 103 x Jam 103 and Jam 104 f Jam 104 in the next generation were made for the induction of virus diseases due to the transmitted virus. The frequency of cytoplasmic polyhedrosis due to the induction in the F$_1$ generation was markedly higher in the cross-batches, male$\times$female and male$\times$female in which inoculated individuals were used as fem ale parents than in the cross-batches, male$\times$female and male$\times$female in which virus has been not inoculated or inoculated only to male in the previous generation. The tendency of increasing rate was observed in any treatments; such as the inoculations of cytoplasmic polyhedrosis virus (10$\^$5/, 10$\^$6/ 10$\^$7, and 10$\^$8//ml ill different concentration of inocula) , cold-treatment (5$^{\circ}C$, 12hrs or 24hrs), and formalin-feeding treatment (2％ or 3％). The shape of polyhedra (tetragonal in outline) examined in the F, larvae was identified as that of the inoculated polyhedra with partial application of immunofluorescent techniques. These results suggests that the cytoplasmic polyhedrosis virus in B. meri L. are transmitted to the next generation through the egg, apparently in the occult state. And the experimental results of various cross-batches revealed the egg cytoplasm plays an important part i the transmission of the occult virus of the cytoplasmic polyhedrosis virus,

1. 활성 virus T-CPV에 대한 유발현상은 잠103 및 잠104어느 것이나 male$\times$ female 및 male$\times$female 처리가 높았으며, 접중농도에 있어서 male$\times$female 및 male$\times$female 처리의 H-CPV단독 유발현상은 $10^{7}$ /m1이하에서 높은 경향이었다. 2. Formalin첨식에 의한 유발현상은 잠103 및 잠104 어느 것이나 male$\times$female 및 male$\times$female가 높은 경향이 있다. 3. 냉장처리에 의한 유발현상에서도 formalin첨식의 경우와 같은 경향이 있다. 물론, 병장처리에 의하여 중장형다각체병이 유발되는 것은 전대에 접종된 occult virus가 활성화한다는 것이라 생각할 수 있으나 그 유발되는 정도는 역시 occult virus와 관계되는 유전적, 생리적 및 환경적 여러가지 요인들을 생각할 수 있다. 따라서 실제적인 저온에 의한 유발관계에서 사육환경을 지배하는 사육의 온습도, 생리적요인을 지배하는 엽질 등을 감안해야 할 것이다. 본 시험결과에서 보면 occult virus가 차대에 경란전달되어 사육중 유발요인에 따라서 활성화하는 것은 분명하다. 그러나 지금까지 occult virus를 찾아낼 수 있는 방법은 전자현미경 및 혈청학적인 기술에 의존해도 불가능하다. 따라서 잠종을 생산하는 과정에서 occult virus의 유무를 확인할 수 있는 방법은 active virus가 검출되는 나방(모아)을 대상으로 하는 경우로 제한하여 시험을 해야 할 것이다. 여기서 또한 밝혀져야 하는 것은 occult virus 경란전달과 sublethal infection에 의한 경란전달의 차이점인 것이다. 그리고 현재 우리가 보유하고 있는 품종별로 occult virus의 잠재된 상태를 유발요인별로 검토하므로서 저항성 품종육성에도 좋은 자료가 될 것으로 생각한다.