Detection and Genotyping of an Infectious Pancreatic Necrosis Virus from Asymptomatic Rainbow Trout <i>(Oncorhynchus mykiss)</i> Facilities in Mexico

Abstract

Background: Infectious pancreatic necrosis virus (IPNV) is a birnavirus that causes a lethal disease in both hatchery-reared juvenile salmonids and other non-salmonid fishes. IPNV has been classified into seven genogroups based on the analysis of the VP2/NS junction region of the viral A RNA segment. Methods: Ten organisms from two trout-rearing farms were used for viral isolation in RTG-2 cells. Cells were inoculated with samples from spleen, kidneys and pyloric caeca. The viral isolate was initially identified by electron microscopy, and confirmed by a commercial ELISA, RT-PCR and sequencing. A phylogenetic tree was constructed based on the deduced amino acids sequence of VP2. Results: An IPNV genogroup 1, labeled as EdoMex07, was isolated from a pool of renal tissues of five asymptomatic trout. The amino acid sequence analysis of VP2 showed that this IPNV presented the putative VP2 residue (221) already described in asymptomatic trout carriers. Conclusions: The EdoMex07 IPNV isolate belongs to genogroup 1, and has a VP2 phenotype which has been suggested to be involved in the establishment of the carrier state. This EdoMex07 IPNV is currently used as the standard positive control for detection of IPNV in rainbow trout farms in Mexico.

Molecular Characterization of the VP2 Gene of Infectious Pancreatic Necrosis Virus (IPNV) Isolates from Mexico

“…Phylogenetic analysis confirmed the six genogroups reported by Blake et al (2001aBlake et al ( , 2001b) and a seventh by Nishizawa et al (2005), with the GenBank IPNV sequences being grouped as previously reported. Previous studies of the partial sequences of the VP2 gene of Mexican IPNV isolates, such as Guerrero et al (2008) and Barrera et al (2011), reported findings similar to those of the present work, placing the Mexican isolates in genogroup 1 and determining that they are closely related to the highly characterized American Buhl strain (Ortega et al 2002;Barrera et al 2011). The greatest number of highly characterized IPNV isolates is from genogroup 1, which consists primarily of isolates from the USA and Canada.…”

Virulence of infectious pancreatic necrosis virus (IPNV) isolates from Mexico

“…In Mexico, epidemiological studies identified IPNV by the principal national zones of production of rainbow trout [17,21], and in 2009 was reported a prevalence of 11.90% [21]. Genotyping and phylogenetic studies by VP2 gene from Mexican IPNV isolates have been performed [2,7,22], however its biological virulence is unknown. The objective of the present study was to determine the virulence of Mexican isolates in rainbow trout fry and related the results to VP2 amino acid fingerprint of the virus.…”

Genotyping of Infectious Pancreatic Necrosis Virus Isolates from Mexico State

“…Subsequent work reported the presence of IPNV in other states within Mexico (Ortega et al 2007). One of these was analyzed and assigned to genogroup I along with the West Buxton and JasperD strains (Guerrero et al 2008), thus sharing the same branch of the phylogenetic tree as the first Mexican isolate (Ortega et al 2002). However, considering that Mexico traditionally has been dependent on the importation of rainbow trout eggs from various countries to meet domestic demand, we can expect that some of the isolates obtained will correspond to different genogroups, as has been reported in other countries (Heppell et al 1992;Cutrin et al 2004).…”