Genotipificacion y relacion hospedador especifica del virus de la necrosis pancreatica infecciosa en Chile

Abstract

RESUMEN. Se analizaron muestras de órganos (riñón y bazo) de las principales especies de salmónidos cultivados en Chile a través de la reacción en cadena de la polimerasa anidada (PCR anidado) para detectar la presencia del virus de la necrosis pancreática infecciosa (IPNV). La técnica resultó ser eficiente y sensible, permitiendo amplificar material genético del virus para su secuenciación directamente desde los tejidos, incluso desde muestras que no pudieron ser aisladas en cultivo celular. A través del análisis filogenético se detectaron los dos genogrupos descritos previamente en el país, i.e., europeo (Genogrupo 5) y americano (Genogrupo 1), siendo cuantitati-vamente predominantes los IPNV del Genogrupo 5 (78,8%). Dentro del Genogrupo 1, se observó claramente la formación de un sub-grupo de virus chilenos separados de las cepas de referencia (e.g., WB, VR-299), por lo que se propone su denominación como genotipo chileno. Adicionalmente, se observó una relación estadística-mente significativa hospedador-específica entre los genogrupos identificados: los virus del Genogrupo 5 provienen de Salmo salar mientras que los del Genogrupo 1 provienen de Oncorhynchus mykiss u O. kisutch (P < 0,001). La asociación de esta relación hospedador-específica con la virulencia puede proveer información importante para el manejo y control de IPNV en Chile. Palabras clave: virus, IPNV, PCR anidado, genotipificación, filogenia, relación hospedador-específica, gen VP2. Genotyping and host-specific relationship of infectious pancreatic necrosis virus in ChileABSTRACT. Samples of fish organs (kidney and spleen) from the main salmonid species farmed in Chile were analyzed through the nested polymerase chain reaction (nested PCR) to detect the presence of infectious pancreatic necrosis virus (IPNV). The technique proved to be efficient and sensitive, allowing amplification of viral genetic material for sequencing directly from tissue, even from samples that could not be isolated in cell culture. The phylogenetic analysis showed the two genogroups previously described in the country, i.e., European (Genogroup 5) and American (Genogroup 1), being the IPNV that belong to Genogroup 5 the dominant one (78.8%). It is clear that the Chilean IPN viruses are clustered within the Genogroup 1 forming a sub-group that is separated from the reference strains (e.g., WB, VR-299), hence we propose its denomination as a Chilean genotype. Additionally, a statistically significant host-specific relationship was observed between the genogroups identified: viruses from Genogroup 5 were detected in Salmo salar, while the ones from Genogroup 1 were detected in Oncorhynchus mykiss or O. kisutch (P < 0.001). The association of this hostspecific relationship with the virulence can provide important information for the management and control of IPNV in Chile.

Comparison of Mortality and Viral Load in Rainbow Trout (Oncorhynchus mykiss) infected with Infectious Pancreatic Necrosis Virus (IPNV) Genogroups 1 and 5

“…Our findings suggest that IPNV isolates from genogroup 1 were more virulent, i.e caused a higher mortality rate, than isolates from genogroup 5 in rainbow trout. This lends support to previous findings that suggested a host-specific relationship between IPNV isolates from genogroup 1 and salmonids from the genus Oncorhynchus farmed in Chile, based on the data from more than one hundred Chilean isolates from both genogroups (Tapia et al, 2015; Torres et al, 2016). Furthermore, since the publication of those studies these authors have continued to sequence more IPNV isolates, finding the same association between genogroups and salmonid species (Eissler et al 2017).…”

“…More recently, Torres et al . (2016) analysed data from Chilean isolates and suggested a host-specific relationship between the reported genogroups and the salmonid species cultivated in the country, since isolates belonging to genogroup 5 were mainly isolated from S. salar , while IPNV genogroup 1 was mostly isolated from O. mykiss or O. Kisutch .…”

Comparison of mortality and viral load in rainbow trout (Oncorhynchus mykiss) infected with infectious pancreatic necrosis virus (IPNV) genogroups 1 and 5

“…Our findings suggest that IPNV isolates from genogroup 1 were more virulent, that is caused a higher mortality rate, than isolates from genogroup 5 in rainbow trout. This lends support to previous findings that suggested a host‐specific relationship between IPNV isolates from genogroup 1 and salmonids from the genus Oncorhynchus farmed in Chile, based on the data from more than one hundred Chilean isolates from both genogroups (Tapia et al, ; Torres et al, ). Furthermore, since the publication of those studies these authors have continued to sequence more IPNV isolates, finding the same association between genogroups and salmonid species (Eissler et al, ).…”

“…Recently, Torres, Eissler, Tapia, Espinoza, and Kuznar () analysed data from Chilean isolates and suggested a host‐specific relationship between the reported genogroups and the salmonid species cultivated in the country, since isolates belonging to genogroup 5 were mainly isolated from S. salar , while IPNV genogroup 1 was mostly isolated from O. mykiss or O. Kisutch . However, to date there are no experimental studies aimed to evaluate a relationship between these two genogroups and the differential susceptibility between host species.…”

Infectious pancreatic necrosis virus in salmonids: Molecular epidemiology and host response to infection

“…For many years, the Chilean salmon industry imported salmon eyed eggs from North America and Europe, where these genogroups are prevalent. More recently, Torres et al 95 suggested there is a host‐specific relationship between the two reported genogroups and the salmonid species cultivated in the country: the isolates belonging to Genogroup 5 were mainly isolated from S. salar , while IPNV Genogroup 1 was mostly isolated from O. mykiss and O. kisutch .…”