Deformities in Litopenaeus vannamei caused by infectious hypodermal and hematopoietic necrosis viral (IHHNV) infection in intensive grow-out ponds of South east coast of India

Abstract

Infectious hypodermal and hematopoietic necrosis virus (IHHNV) is a harmful virus that is responsible for the remarkable economic loss of Litopenaeus vannamei culture. IHHNV was first observed in shrimps, which were characterized by light microscopy, SEM, and TEM. The infected shrimps showed severe morphological deformity, including reduced body size, bent rostrum, shrunken and twisted antenna, rough cuticles, shrunken eyes, and rigid muscles. The antennal segments of the infected shrimps were fused together, puffy, dented, bent, and rough, as observed under a scanning electron microscope. The affected shrimps also showed tumor-like growth (hyperplasia) at the lateral position of the carapace in which the gastrofrontal sulcus was bent. This hyperplasia was found to be soft. In addition, the connective tissue of the diseased shrimp was in a degraded state, and the muscle fibers were despoiled. The nucleus of the cells from the infected gill cells of the shrimps was almost occupied by viral icosahedral particles, which TEM revealed. These viral particles were also found in the cytoplasm in a scattered manner within the same cells and were identified as IHHNV, as confirmed by polymerase chain reaction.