Mechanism Of Inhibiting The Proliferation Of HaNPV By C-type Lectin In Cotton Bollworm

Helioverpa armigera, a worldwide polyphagous pest, can not only detriment cotton, but also damage many crops, like corn, wheat and vegetables, such as tomatoes and peppers. In recent years, the breeding of genetically modified cotton played an important role in controlling the dangers of Helioverpa armigera. However, with the plant of BT transgenic cotton becoming longer and more, Helioverpa armigera in the field has produced resistance, so control of cotton bollworm is still very urgent. Helioverpa armigera. Nuclear polyhedrosis viruses(NPV), a kind of virus with strong host specificity, is characterized of high security, longer effective, environmentally friendly, thus becoming the earliest type of viral pesticide which is approved for biological control.Helicoverpa armigera NPV(HaNPV) parasitize in Helioverpa armigera specifically. As a pathogen-specific virus, HaNPV is an important factor for successfully restricting its population.Nevertheless, the spreading mechanism in vivo of this virus remains unclear. Pattern recognition receptor can effectively recognize other components when the creature is infected with virus, which becomes the earliest and most important part in immune response. C-type lectin, one of the most important pattern recognition receptors, can identify the pathogenic related molecular on the surface of microorganism.C-type lectin plays an important role in innate immune responses.Previous study results had confirmed that Helicoverpa armigera C-type lectin Ha-lectin can inhibit the proliferation of nuclear polyhedrosisbudding virus(BV) in Helicoverpa armigera, but the inhibition mechanism still unknown. When Helicoverpa armigerawas infected with HaNPV, Ha-lectin dramatically increase in granulosa cells, and was induced to express in viral-infected plasma cells.Fluorescent labeled occlusion derived virus(ODV) showed they have co-location in blood cells. The deathof the host and the onset time of pesticides depend on the infection and proliferation rate of BV in vivo.Therefore, in this study, the molecular mechanism of Ha-lectin inhibiting BV proliferation was reveled from the point of the interaction of host protein and viral protein.In this paper, the decomposition reaction of the virus triggered by Ha-lectin protein in extracellular serum was quantitively detected, discovering that Ha-lectin protein in serum promoted virus decomposition.Compared with normal serum, the virus decomposition weakened in inactivated serum, serum interfered with Ha-lectin dsRNA and serum mixed with Ha-lectin antibody. Virus adsorption method was used to detect the effect of Ha-lectin on host cell adsorption capacity of Ha NPV buddingvirus BV, finding that the Ha-lectin can promote the virus adsorption on haemocytes. But in fat bodycells, after Ha NPV budding virus BV and different treatmented serum incubated, adsorption ability of virus on fat body cells showed no signicicant difference in normal serum, RNAi interferenced serum and serum mixedwith Ha-lectin antibody.The results indicated that the fat body is different from hematocytes and Ha-lectin could not promote the virus adsorptionthe fat body cell in fat body. Besides, the proliferation of Ha NPV budded virus(BV)in hematocyte and fat body were also detected, virus proliferation was faster in fat body than in hematocytes.This result suggested that hematovytes inhibited virus proliferation as immune cells. C-type lectin of Helicoverpa armigeramight act as opsonin, promoting the absorption and phagocytosis of hematocytes on virus and inhibiting the virus proliferation in hematocytes.In order to further reveal the action mechanism of C-type lectin Ha NPV, proteins interacting with Ha-lectin in the course of BV virus infection.were studied by the co-immuno-precipitation and mass spectrometry. Analysis and comparison of the serum protein of the cotton boll worm infected by virus and non infected virus, showed 35 protein groups and 45 proteins, such as immune related proteins, regulatory proteins, enzymes and tissue proteins. It is speculated that the proteolytic enzymes and immune proteins inthe blood lymph may be involved in the decomposition of the virus and the adsorption of the virus to the blood cells, thus inhibiting the proliferation of the virus. It is possible that the virus may not interact directly with the cell membrane, but first becoming protein complex with C-type lectin in host opening blood cavity, via the C-type lectin recognition cell membrane membrane receptor, triggering endocytosis and inhibiting virus proliferation. In order to find the receptor which can be combined with the HaNPV and the C-type lectin complex, the protein of the blood cell membrane of Helioverpa armigera was extracted,and the membrane proteins were analyzed by immunoprecipitation and mass spectrometry. The rusults provided important basis and clue for the study of spreading mechanism of virus in Helioverpa armigera,especially for confirming a key factor to NPV infection at the early stage of virus infection. Our research lay the foundation for improving the insecticidal efficacy of biological pesticide and discovering new pest control targets, and also has great application value and practical significance.