Investigação da susceptibilidade do Macrobrachium rosenbergii ao Vírus da Mionecrose Infecciosa (IMNV) através de infecção experimental

Abstract

Aquaculture is the fastest growing food production sector in the world. In Brazil, shrimp farming accounts for almost 20% of national aquaculture production. Although this activity began in the 1970s with the cultivation of marine shrimp Litopenaeus vannamei, the cultivation of freshwater shrimp, Macrobrachium rosenbergii, is growing in the country. Even though recent national data are not yet available, M. rosenbergii already accounts for about 3% of global crustacean production and is increasing in commercial production. This implies the emergence of a series of problems in the production chain, one of the main ones can be highlighted the emergence of diseases, as they are capable of causing great economic losses, as well as directly impacting the environment. Given this problem, the objective of this work is to investigate the susceptibility of shrimp M. rosenbergii to Infectious Myonecrosis Virus (IMNV) through intramuscular inoculation with subsequent determination of infection via nested-PCR and lesions suggestive by histopathology. For the study, 54 shrimps were acquired and divided according to life stage (Group1 = subadults and Group 2 = adults) and subsequently infected with IMNV intramuscularly. Within each group, a portion of animals that were not infected with the virus were reserved, received only one injection of saline and was called Negative Control. Exposure to the virus lasted 21 days and was monitored daily for water quality and mortality over time. After 21 days of the experiment, the animals were submitted to confirmatory diagnosis of IMNV infection through nested-PCR and histopathological analysis. All water quality variables analyzed were subjected to statistical analysis, following the assumptions of normality (Shapiro- Wilk) and homogeneity (Bartlett). Variance analysis (ANOVA) and Student's t-test were performed using the RStudio program (version 3.6.1) and except for pH and ammonia, the other water quality variables (nitrite and temperature) did not differ statistically. The nested-PCR data and mortality were submitted to descriptive statistics. All animals inoculated intramuscularly with IMNV, subadults and adults of M. rosenbergii, were positive via nested-PCR, confirming the sensitivity of this species to Infectious Myonecrosis Virus.