Avaliação da suscetibilidade do camarão-sossego, Macrobrachium jelskii, ao vírus da síndrome da mancha branca (WSSV)

Abstract

Crustaceans of the genus Macrobrachium are commonly found in tropical and subtropical regions. Brazil has 15 native species of this genus, with some species cultivated in captivity and exploited mainly by artisanal fishing, notably M. amazonicum, M. brasiliense and M. jelskii. Macrobrachium jelskii is a small shrimp found in almost all Brazilian states, typically freshwater and can be found in marginal and lentic waters. Because of this, especially with the increasing breeding of Penaeus vannamei in fresh and oligohaline waters, these animals can be found in cultivation nurseries, through captured water. Previous studies on other species in the genus Macrobrachium have shown that some organisms are susceptible to white spot disease (WSD). Given this context, the objective of the present work was to determine whether the native species Macrobrachium jelskii manifests this viral pathology when experimentally contaminated by intramuscular inoculation. For the experiment, 150 animals were used, 75 for control and 75 for intramuscular inoculation. The experiment lasted 60 days, 30 days of growth and acclimatization and 30 days of viral challenge. Six samples were carried out for viral load analysis, removing nine organisms from each treatment per sample, on days T0, T5, T10, T15, T20 and T30. For histological analyses, four samples were made, in which the gills, hepatopancreas and intestine were analyzed. Samples were made on days T0, T5, T15 and T30. For samples from the infected group, symptoms were only presented on the second day after infection, mainly lethargy and lack of appetite. All samples destined for histology did not have cellular changes characteristic of WSD, including those that underwent viral challenge. However, after real-time PCR analysis, the presence of viral load was verified in all samples submitted to the virus, with viral loads between 5.67 x 102 and 1.41 x 105. It was concluded that the native species M. jelskii are susceptible to the white spot virus and these organisms only showed symptoms of lethargy and lack of appetite the day after the start of the viral challenge, with a survival rate greater than 10%. The disease did not manifest itself histopathologically, however confirmation of the viral load by real-time PCR until the last sampling (T30) shows that M. jelskii shrimp are capable of carrying the virus.