Evidence that the major hemolymph protein of the Pacific oyster, Crassostrea gigas, has antiviral activity against herpesviruses

Antiviral immunity in marine molluscs

“…Investigations into the antiviral activity of molluscan AMPs and tissue homogenates is hampered by the lack of continuous cell lines from marine molluscs (Yoshino et al, 2013) and the fact that OsHV-1 cannot be cultured in primary cell cultures from bivalves (details in Garcia et al, 2011). Numerous studies have therefore utilized a heterologous model involving HSV-1 and African green monkey kidney (Vero) cells to identify antiviral compounds in tissue homogenates from commercially important bivalves (Carriel-Gomes et al, 2006;Defer et al, 2009;Green et al, 2014c;Olicard et al, 2005a, b;Segarra et al, 2014a;Zeng et al, 2008) and gastropods (Dang et al, 2011;Zanjani et al, 2014).…”

“…and no studies of cephalopods. Studies investigating the antiviral response of molluscs have mainly focused on identifying antiviral compounds, measuring immune enzyme activity or characterizing the transcriptional response to OsHV-1 infection Dang et al, 2011Dang et al, , 2013Fleury & Huvet, 2012;Green & Montagnani, 2013;Green et al, 2014c;Jouaux et al, 2013;Moreau et al, 2015;Normand et al, 2014;Olicard et al, 2005a, b;Renault et al, 2011;Rosani et al, 2014;Segarra et al, 2014a, c). These studies suggest that the molluscan antiviral response has similarities to the vertebrate interferon pathway (Green & Montagnani, 2013).…”

“…Anti-HSV-1 activity of Crassostrea gigas haemolymph corresponds to a copper containing glycoprotein, termed cavortin (GenBank no. AY551094) that exerts its antiviral activity by interfering with virus replication (Green et al, 2014c). Cavortin is the major plasma protein in the oyster and the protein has an extracellular superoxide dismutase domain (Gonzalez et al, 2005;Itoh et al, 2011).…”

“…Selective breeding programmes would benefit from identifying the genetic mechanism(s) utilized by resistant molluscs for maintaining viral loads below the mortality threshold. A good starting point would be the antiviral plasma proteins (haemocyanin and cavortin) that are known to interfere with mammalian virus replication (Dang et al, 2011;Green et al, 2014c;Olicard et al, 2005b). Normand et al (2014) concluded expression levels of superoxide dismutase metalloenzymes (i.e.…”

“…cavortin) may partly determine resistance of Crassostrea gigas to OsHV-1 associated mortality. Plasma antiviral activity is a trait under genetic control in populations of Crassostrea gigas (Green et al, 2014c) and abalone (unpublished data).…”