Um enfoque imunológico sobre infecção viral em Litopenaeus vannamei coletados em fazenda de cultivo do Nordeste do Brasil

Abstract

The shrimp farming has become an important aquaculture industry in the world. Brazil is becoming a leading global producer of shrimp Litopenaeus vannamei. However, outbreaks of viral diseases are affecting the aquaculture industry worldwide, causing significant economic losses. Among the viral agents that affect the marine shrimp Infectious hypodermal and hematopoietic necrosis virus (IHHNV) and infectious myonecrosis virus (IMNV) are prevalent epizootic viral agents in Brazil. Within this context, this study aimed to analyze samples of virus-infected shrimp collected from farms in northeastern Brazil, as well as analyzing the expression levels of molecules of immunity during infection of animals. After a period of unusual rains in a routine monitoring program for the diagnosis of diseases were collected gills of juvenile shrimp with signs of viral disease. For the diagnosis of infection were employed molecular techniques such as conventional PCR, reverse transcription coupled with PCR (RT-PCR) and quantitative PCR (qPCR). Through a combination of different molecular techniques has shown that most of shrimp patients were co-infected with both viruses, IHHNV and IMNV. This study was the first to demonstrate the occurrence of a natural co-infection, caused by IHHNV and IMNV in penaeid shrimp cultured in northeastern Brazil. The reciprocal values for viral load may suggest that competition is occurring between the two viruses to infect the host. To understand how the key molecules of innate immunity respond to this double infection, the level of HSP-70, crustin, peneidinas-3a and C-type lectin-br1 were assessed by quantitative PCR. In tests using linear correlation, HSP-70 expression is regulated by the presented IHHNV in doubly infected shrimp gills, however, transcripts of other genes analyzed showed no statistically significant regulated expression. These results suggest that HSP-70 may be a differential modulator co-infection viral in shrimp, L. vannamei.