Fish Diseases and Management

3.2.5.Broad antiviral activity in tissues of crustaceans

Innate antiviral substances occur in vertebrates and may function as host defences. Virus infections are common among invertebrates, but little is known about the ability of invertebrates to control viral infections. Pre-existing antiviral substances may be particularly important, since invertebrates lack the antiviral defence conferred by specific immunity. Studies conducted in invertebrates revealed that tissue extracts of blue crab (Callinectes sapidus), shrimp (Penaeus setiferus), and crayfish (Procambarus clarkii) contained antiviral activities that inhibit a variety of DNA and RNA viruses, i.e. Sindbis virus (SB), vaccinia virus (VAC), vesicular stomatitis virus (VS), mengo virus (MENGO), banzi virus (BANZI) and poliomyelitis (POLIO). The main antiviral activity in the inhibitor preparation from blue crab resided in an approximately 440 kDa fraction. It was inactivated significantly by lipid extraction, but not by proteinase K or glycosidases. The antiviral mechanism of the inhibitor from the blue crab was inhibition of virus attachment to eukaryotic cells, as evidenced by inhibitory activity at 4°C. These antiviral substances may function as innate host defences in these species that lack specific antibody immunity.