Managing infectious myonecrosis virus (IMNV) in Vannamei shrimp culture: Learning by doing

Abstract

Infectious Myonecrosis Virus (IMNV) was first reported in Indonesia in 2006. By 2009, it spread all over the significant shrimp farming areas in Indonesia. There was a significant drop in shrimp production due to IMNV outbreak. Several efforts were made to understand the nature, mode of disease progression, and minimize the virus load. The IMNV progression was divided into four stages. Chemicals, especially of chlorine origin, showed protection against IMNV. Tilapia came up with an effective biological remedy against IMNV. The blend of essential oils, pondguard showed significant protection against IMNV in the laboratory and farms.

Viral Shrimp Diseases Listed by the OIE: A Review

“…This suggests that the MCP could be used as a target gene to track the movement of IMNV [ 77 ] ( Table 3 ). Through subsequent analysis, it was confirmed that the IMNV in Brazil and Indonesian reported by GenBank had nucleic acid sequence identity of 99.6% [ 82 ]. The capsid protein has a major role in virus adhesion, virulence, and cell entry, and the MCP gene (nt 2248~4953) of IMNV also contains a variable region with 72 polymorphic sites, so that the MCP gene sequence can be used to trace the origin of a new strain [ 82 ].…”

“…IMNV is a single molecule of double-stranded RNA forming a monopartite genome that is 7561–8230 bp in length with two open reading frames (ORFs). It is a non-enveloped icosahedral virus with a diameter of 40 nm and fiber-like protrusions on the surface [ 74 , 82 ] ( Table 1 ). IMNV is taxonomically a totivirus belonging to Totiviridae family that is similar to Protozoa and Fungal viruses.…”

“…Although the exact mechanism for IMNV transmission is unknown, there is also the possibility of horizontal transmission through cannibalistic behavior or the water via infected shrimp, and vertical transmission from broodstock to progeny [ 76 ]. The source of vertical transmission is assumed to be maternal based on the low sperm cell survival rate of naturally infected males and the 100% positive occurrence in the ovaries of female shrimp infected with IMNV [ 82 ]. Although specific data on the vector of IMNV are lacking, it has a non-envelope particle structure like TSV (non-enveloped virus particles have high survival rates in the gastrointestinal tracts of animals), and thus has the potential to maintain infectivity in the intestines and feces of seabirds that feed on IMNV-infected dead or dying shrimp [ 88 ].…”

“…In addition, the damage at the early steps of IMNV infection can be repaired in the muscle tissues [ 76 ]. Although IMNV is not fatal when compared to WSSV and YHV, this virus is a stress-dependent virus, which is lethal to P. vannamei when there are rapid changes in water quality parameters such as pH, temperature, plankton, and dissolved oxygen [ 82 ]. Due to its slow disease progression, IMNV can cause significant economic losses due to high feed conversion efficiency as the infected individuals consume feed continuously [ 76 ].…”

“…Therefore, restocking with IMNV-resistant individuals such as P. monodon and P. stylirostris could be a useful method to reduce mortality losses [ 76 ]. To prevent the vertical transmission of IMNV, eggs and larvae must be disinfected, and biological security measures, appropriate quarantine, and SPF (specific pathogen free) bloodstocks procedures implemented, in addition to stocking density decreases, stress reduction in the culture environment, and immune-stimulant administration [ 82 ].…”