Susceptibilidade do camarão rosa Farfantepenaeus subtilis (Pérez-Farfante, 1967) ao vírus da Mionecros Infecciosa (IMNV)

Abstract

Viral diseases are causing great damage in shrimp farming. With the IMN virus emergence in Northeastern Brazil in 2002, the shrimp producers faced an unknown disease that caused significant losses for the industry. Thus, a better knowledge about this disease and the investigation of how other species of shrimp are affected by the IMN virus will be an important contribution for the aquaculture industry. The objective of this study is to evaluate the susceptibility of Farfantepenaeus subtilis from the Brazilian coast, to the IMN virus. To conduct the bioassay it was used 200 healthy young shrimps kept in individual tanks of 4L for 30 days. The experimental design was composed by two separated groups: a control group and a challenged one which was exposed to the IMN virus. The challenged group was fed on L. vannamei muscle contaminated with IMNV and the control group was fed on muscle of L. vannamei free of the virus, for 3 days per os. After the challenge procedures, random samples of 40 animals, 20 control and 20 challenged were taken, every five days (5°, 10°, 15°, 20° and 30°). On each sampling hemolymph was drawn for the total count of hemocytes (THC), gills were taken for analysis by RT / PCR and then each animal was fixed with Davidson solution for histological analysis. The molecular analysis, using the methodology of Kit IQ2000, showed that among 100 animals challenged only ten (10%) were positive for infection. In histological analysis a low hemocyte infiltration was observed in muscles and a slight presence of hemolymph coagulation was detected between muscle fibers characterizing a mild infection. According to the Student t test for independent data, there was a statistically significant difference (p ≥ 0.05) between the THC of challenged group and the control group sample of 30 days. The study showed wild specimens of F. subtilis to be susceptible to infection with IMNV