核型多角体病毒对烟青虫血淋巴的影响

Hemolymph of Heliothis assulta infected by Heliothis assulta nucleopolyhedrovirus

为研究烟青虫核型多角体病毒(Heas NPV)侵染所引发的免疫机理,本试验以浓度105PIB/μl、106PIB/μl和107PIB/μl Heas NPV侵染5龄幼虫,分别测定了处理后烟青虫幼虫血淋巴中血细胞总量、浆血细胞和颗粒细胞的数量、酚氧化酶(PO)的活性以及血淋巴的体外黑化率,同时还用显微镜观察了Heas NPV侵染血细胞的过程。结果显示:与对照组相比,106PIB/μl和107PIB/μl的Heas NPV溶液处理导致5龄幼虫血淋巴中血细胞总量、浆血细胞和颗粒细胞的数量显著上升(P<0.05),并且在感毒后3 d达到峰值。105PIB/μl的Heas NPV溶液处理后,烟青虫5龄幼虫血淋巴中血细胞总量、浆血细胞和颗粒细胞的数量呈缓慢上升趋势。106PIB/μl的Heas NPV溶液处理的5龄幼虫的PO活性先增长后下降。在连续观察的5 d内,对照组幼虫血淋巴体外黑化率始终为100%,而处理组幼虫血淋巴体外黑化率呈下降趋势。以上结果说明,烟青虫幼虫血淋巴中的细胞免疫和体液免疫在Heas NPV侵染防御中发挥了重要作用,幼虫感染病毒后通过血细胞数量的增加和PO活性的升高来清除外来病原物。

The immune mechanism of the Heliothis assulta larvae infected with Heliothis assulta nucleopolyhedrovirus (Heas NPV) was studied through measuring the number of total hemocytes,plasmatocytes and granular hemocytes in the5 th instar larvae of H.assulta exposed to 105PIB/μl,106PIB/μl and 107PIB/μl Heas NPV,respectively,and the activity of phenol oxidase (PO) and melanization rate of hemolymph.The number of total hemocytes,plasmatocytes and granular hemocytes and the activity of PO increased in the 5th instar larvae of H.assulta infected with 106PIB/μl and 107PIB/μl Heas NPV (P < 0.05),and peaked at the 3rd day.However,the number of total hemocytes,plasmatocytes and granular hemocytes and the activity of PO rised slowly in the 5th instar larvae of H.assulta infected with 105PIB/μl Heas NPV.The in vitro black rate of hemolymph of larvae in the control group stayed 100% within five days of treatment,while the black rate in the infected group presented a downward trend.A conclusion can be drawn that cellular immunity and humoral immunity of hemolymph play important roles in the defense of H.assulta larvae against Heas NPV infection,and the foreign pathogens were eliminated through the increases of the number of hemocytes and the activity of PO.