RESUMO
The thioredoxin (TRX) system in crustaceans has demonstrated to act as a cell antioxidant being part of the immune response by dealing with the increased production of reactive oxygen species during bacterial or viral infection. Since the number of marine viruses has increased in the last years significantly affecting aquaculture practices of penaeids, and due to the adverse impact on wild and cultured shrimp populations, it is important to elucidate the dynamics of the shrimp response to viral infections. The role of Litopenaeus vannamei thioredoxin (LvTRX) was compared at both, mRNA and protein levels, in response to two viruses, the white spot syndrome virus (WSSV) and the infectious hypodermal and hematopoietic necrosis virus (IHHNV). The results confirmed changes in the TRX gene expression levels of WSSV-infected shrimp, but also demonstrated a more conspicuous response of TRX to WSSV than to IHHNV. While both the dimeric and monomeric forms of LvTRX were detected by Western blot analysis during the WSSV infection, the dimer on its reduced form was only detected through the IHHNV infectious process. These findings indicate that WSSV or IHHNV infected shrimp may induce a differential response of the LvTRX protein.
Assuntos
Densovirinae/fisiologia , Regulação da Expressão Gênica , Penaeidae , Tiorredoxinas/genética , Tiorredoxinas/imunologia , Vírus da Síndrome da Mancha Branca 1/fisiologia , Animais , Perfilação da Expressão Gênica , Brânquias/imunologia , Brânquias/virologia , Penaeidae/imunologia , Penaeidae/virologia , Fatores de TempoRESUMO
The Pacific white shrimp, Litopenaeus vannamei, is the most important shrimp species in volume in world aquaculture. However, in recent decades, outbreaks of diseases, especially viral diseases, have led to significant economic losses, threatening the sustainability of shrimp farming worldwide. In 2004, Brazilian shrimp farming was seriously affected by a new disease caused by the Infectious myonecrosis virus (IMNV). Thus, disease control based on rapid and sensitive pathogen detection methods has become a priority. In this study, a specific quantitation method for IMNV was developed using real-time PCR with SYBR Green chemistry and viral load of the principal target tissues of chronically infected animals was quantified. The quantitative analysis revealed that mean viral load ranged from 5.08×10(8) to 1.33×10(6)copies/µg of total RNA in the hemolymph, 5.096×10(5) to 1.26×10(3)copies/µg in the pleopods, 6.85×10(8) to 3.09×10(4)copies/µg in muscle and 8.15×10(6) to 3.90×10(3)copies/µg in gills. Different viral loads of IMNV were found with greater values in the hemolymph and muscle, followed by the pleopods and gills.
Assuntos
Corantes Fluorescentes , Penaeidae/virologia , Infecções por Vírus de RNA/veterinária , Vírus de RNA/isolamento & purificação , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos , Actinas/genética , Animais , Brasil/epidemiologia , Clonagem Molecular , Vetores Genéticos/genética , Vetores Genéticos/metabolismo , Brânquias/virologia , Hemolinfa/virologia , Músculos/virologia , Penaeidae/genética , Plasmídeos/genética , Plasmídeos/metabolismo , Infecções por Vírus de RNA/diagnóstico , Infecções por Vírus de RNA/epidemiologia , Infecções por Vírus de RNA/virologia , Vírus de RNA/genética , Vírus de RNA/patogenicidade , RNA Viral/análise , Sensibilidade e Especificidade , Carga ViralRESUMO
Recurrent episodes of mortality of Crassostrea gigas cultured in northwestern Mexico have been occurring since 1997. Previous studies on bacteria, protozoans, and metazoans as presumptive causal agents have been inconclusive. However, erosions in the marginal indentation of gills have been frequently observed in oysters from areas affected by mortality events, and in 2000 those lesions were associated with the detection of a herpes-like virus. The present study aimed to describe the histological alterations of eroded gills and to determine whether ostreid herpesvirus 1 (OsHV-1) or a related virus was associated with them using in situ hybridization (ISH). Histology showed that gill filaments were fused. In severe cases, deformation of the interlamellar junctions, swelling, and the loss of water channels was observed. ISH analysis revealed the presence of OsHV-1 DNA or a related virus in cells of the gills. Some labeled cells were large with dark granules inside their cytoplasm. These cells were surrounded by infiltrating hemocytes. Some cells interpreted as hemocytes were labeled and observed in eroded and non-eroded areas of the gill. Large cells detected by ISH were also observed by conventional histology with hematoxylin-eosin staining. Whether the virus produces the erosions in the gills, or the erosions in the gills are produced by an unknown condition and favor the presence of the virus, remains unresolved. It is also not clear whether the lesions contribute to mortality.
Assuntos
Crassostrea/virologia , Brânquias/patologia , Brânquias/virologia , Herpesviridae/isolamento & purificação , Animais , Aquicultura , Herpesviridae/classificação , MéxicoRESUMO
Oysters Crassostrea gigas were placed at water supply canals of three shrimp farms in Guasave, Mexico where WSSV outbreaks occur. Animals were sampled through April-August and September-December to detect WSSV DNA. By using three different PCR protocols, only oysters from a farm undergoing a WSSV outbreak were found WSSV-positive in gills and digestive gland. Two WSSV amplicons were sequenced and they corresponded over 99% to WSSV genome segments. Results showed that oysters can capture WSSV particles suspended in water. Susceptibility of oysters to WSSV infection and their role as a carrier remain to be determined.