In vitro propagation of infectious myonecrosis virus in C6/36 mosquito cell line

Abstract

Infectious myonecrosis (IMN) is an important shrimp viral disease caused by infectious myonecrosis virus (IMNV). Based on previous reports, an attempt was made to propagate IMNV in apparently healthy C6/36 subclone of Aedes albopictus cell line. The confirmatory assays such as RT‐PCR, real‐time PCR and bioassay revealed that C6/36 cells were found to be susceptible to IMNV and these cells could be used easily for isolation and propagation of IMNV. The results of real‐time PCR assay showed that a lower CT value of 22.25 in IMNV‐infected cells was obtained on 10 day post‐infection (d p.i.), whereas the higher CT value of 35.21 was obtained in IMNV‐infected cells on 2 d p.i. There is no significant difference between CT values of IMNV production in vitro using C6/36 cell line and in vivo using shrimp. The IMNV propagated in C6/36 cells is capable of infecting shrimp and caused 100% mortality in shrimp. Clinical signs observed in shrimp injected with IMNV propagated in C6/36 cell line were found to be similar to naturally infected shrimp.

Viral Shrimp Diseases Listed by the OIE: A Review

“…IMNV was first reported in 2003 in P. vannamei cultured in northeastern Brazil, then in Indonesia (2006), and most recently in India (2016), Malaysia (2018) and Indonesia (2018) [ 78 , 79 ] ( Figure 12 ). Until the IMNV virus was reported in India in 2016, it had only occurred in Brazil and Indonesia [ 80 ].…”

“…Although IMNV can induce an increase in mortality due to an acute infection in P. vannamei , the infection is usually detected by observing chronic symptoms in the host rather than a rapid mortality. The symptoms displayed by P. vannamei infected with IMNV include focal to extensive white necrotic areas in the striated muscle, especially the distal abdominal segments and tail fan [ 79 ], as well as a slow mortality that persists during the culture period (cumulative mortality reaching up to 70%) [ 81 ].…”

“…Furthermore, the wild Southern brown shrimp, Penaeus ( Farfantepenaeus ) subtilis is also susceptible to IMNV infection [ 76 , 84 ]. IMNV is known to only infect Penaeid shrimp (4 shrimp species: P. vannamei , P. sylirostris , P. monodon , P. subtiltis ), but can do so at all life stages including post larvae, juvenile, and adult, but mortality was observed only in the juveniles and adults showing symptoms of a cooked appearance [ 76 , 79 ] ( Figure 13 ). In IMNV-infected shrimp, extensive white necrosis of the striated muscle, especially the distal part of the abdomen and tail fan, may progress, and dissection of moribund shrimp may show enlarged lymphoid organs more than twice the normal size [ 62 ] ( Figure 13 C,D).…”