White spot syndrome virus envelope protein VP28 is involved in the systemic infection of shrimp

White spot syndrome virus (WSSV) is a large DNA virus infecting shrimp and other crustaceans. The virus particles contain at least five major virion p roteins, of which three (VP26, VP24, and VP15) are present in the rod-shape d nucleocapsid and two (VP28 and VP19) reside in the envelope. The mode of entry and systemic infection of WSSV in the black tiger shrimp, Penaeus mon odon, and the role of these proteins in these processes are not known. A sp ecific polyclonal antibody was generated against the major envelope protein VP28 using a baculovirus expression vector system. The VP28 antiserum was able to neutralize WSSV infection of P. monodon in a concentration-dependen t manner upon intramuscular injection. This result suggests that VP28 is lo cated on the surface of the virus particle and is likely to play a key role in the initial steps of the systemic WSSV infection in shrimp. (C) 2001 Ac ademic Press.