Characterization of two monoclonal antibodies, 38F10 and 44D11, against the major envelope fusion protein of Helicoverpa armigera nucleopolyhedrovirus

Abstract

The envelope fusion protein F of baculoviruses is a class I viral fusion protein which play a significant role during virus entry into insect cells. F is initially synthesized as a precursor (F₀) and then cleaved into a disulfide-linked F₁ and F₂ subunits during the process of protein maturation and secretion. To facilitate further investigation into the structure and function of F protein during virus infection, monoclonal antibodies (mAbs) against the F₂ subunit of Helicoverpa armigera nucleopolyhedrovirus (HearNPV) (HaF) were generated. Two kinds of mAbs were obtained according to their different recognition epitopes: one kind of mAbs, as represented by 38F10, recognizes amino acid (aa) 85 to 123 of F₂ and the other kind, represented by 44D11, recognizes aa 148 to 173 of F₂. Western blot and immunofluorescence assay confirmed that both of the mAbs recognized the F protein expressed in HearNPV infected cells, however, only 44D11 could neutralize HearNPV infection. The results further showed that 44D11 may not interact with a receptor binding epitope, rather it was demonstrated to inhibit syncytium formation in cells expressing the HaF protein. The results imply that the monoclonal antibody 44D11 recognizes a region within HaF2 that may be involved in the F-mediated membrane fusion process.

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