Detection of the OsHV-1 μVar in the Pacific oyster Crassostrea gigas before 2008 in France and description of two new microvariants of the Ostreid Herpesvirus 1 (OsHV-1)

Oyster mortality

“…175/2010 as 'a genotype of the virus Ostreid herpesvirus-1 (OsHV-1) which is defined on the basis of partial sequence data exhibiting a systematic deletion of 12 base pairs in ORF 4 of the genome in comparison with OsHV-1 (GenBank # AY509253)'. However, Martenot et al (2012) (Lynch et al, 2012), indicating that the introduction of the microvariant lineage may have taken place earlier than generally believed. Strains with the extra guanine were also detected during 2008-2010 in Ireland co-circulating with µVar (Morrissey et al, 2015), in UK in 2013 and in two French strains from 2010 (Renault et al, 2012).…”

“…The first variant of OsHV-1, OsHV-1var was detected in 2001 and was associated with mortality in Manila clam (Ruditapes philippinarum) (Arzul et al, 2001b (Segarra et al, 2010;Martenot et al, 2011;Martenot et al, 2012;Martenot et al, 2013). Between 1995 and 2007, none of the virus strains obtained during summer mortalities were identified as µVar (Segarra et al, 2010).…”

“…In 2008, 47% of isolates from summer mortalities were OsHV-1 µVar. Between 2008 and 2011, the proportion of OsHV-1 µVar has remained high at 86-90 % (Martenot et al, 2012).…”

“…OsHV-1 µVarΔ15 is associated with spat mortality with high viral loads. The OsHV-1 µVarΔ9 was found in healthy adults with lower viral loads but has not been clearly linked with abnormal mortalities Martenot et al, 2012).…”

In situ hybridization and histopathological observations during ostreid herpesvirus-1-associated mortalities in Pacific oysters Crassostrea gigas

“…Genomic variants, based mostly on polymorphism of the C2 and C6 region of the OsHV-1 genome, were reported, and they appeared to differ in virulence (Segarra et al 2010, Martenot et al 2012, Renault et al 2012, Shimahara et al 2012, Bai et al 2015. Perio -ABSTRACT: In a previous longitudinal study conducted during a mortality investigation associated with ostreid herpesvirus-1 (OsHV-1) microvariant in New Zealand Pacific oysters in 2010− 2011, temporality of OsHV-1 nucleic acid detection by real-time PCR assay and onset of Pacific oyster mortality was observed.…”