Association of dual viral infection with mortality of Pacific white shrimp (Litopenaeus vannamei) in culture ponds in India

Abstract

Pacific white shrimp, Litopenaeus vannamei has been introduced recently for culture practice in India. Though SPF stocks are imported for larval production and thereafter culture practice, these are prone to infection with the existing viruses in the environment. Here we report mortality of L.vannamei in several farms in India with minimum biosecurity. The shrimp were harvested early within 50-72 days of culture due to the onset of disease and consequent mortality. As per the analysis carried out, the shrimp were infected with two virus, white spot syndrome virus (WSSV) and infectious hypodermal and hematopoietic necrosis virus (IHHNV). About 80 % of the samples collected had either or both of the viruses. A majority of these samples (60 %) had dual infection with WSSV and IHHNV. Infection of shrimp with WSSV and IHHNV could be detected both by PCR and histopathology. Some of the samples had either exclusively WSSV infection or IHHNV infection and were also harvested before the completion of the required culture period. All the samples analyzed were negative for taura syndrome virus, yellow head virus and infectious myonecrosis virus. While it is difficult to point out the exact etiological agent as the cause of mortality, strict biosecurity measures are advisable for the continuity of L. vannamei culture in India.

Detection of viruses in the exotic shrimp Penaeus vannamei Boone, 1931 cultured in India

“…Earlier researchers have reported the low (32%) and high (66%) prevalence of IHHNV infection of cultured P. vannamei samples in Indian farms (Moger et al, 2011;Otta et al, 2014). In the present study, IHHNV was detected in four shrimp samples out of 81 samples screened, giving an overall occurrence of 4.9%.…”

“…WSSV infection has caused mass mortalities of farmed P. vannamei, bringing huge loss to shrimp farmers around the world like Ecuador (Calderon et al, 1999), Brazil (Cavalli et al, 2008) and Iran (Afsharnasab et al, 2009). Likewise, many researchers have also reported P. vannamei mortality in farms due to WSSV alone or in combination with other pathogens from India (Balakrishnan et al, 2011;Otta et al, 2014;Sanathkumar et al, 2014). In another study from India, high prevalence (72%) of WSSV in cultured P. vannamei samples has been reported (Moger et al, 2011).…”

White spot syndrome virus (WSSV) genome stability maintained over six passages through three different penaeid shrimp species

“…This was indicative of acute WSSV disease, and for P. monodon farmed in India, such disease occurs commonly due to the use of infected seedstock arising as a result of WSSV being prevalent among the wild broodstock used at hatcheries (Remany et al 2012). Acute infection in the L. vannamei was also not unexpected due to the specific pathogen-free L. vannamei being farmed in India remaining highly susceptible to WSSV infection and disease (Otta et al 2014). WSSV disease problems in India are also exacerbated by inadequate pond preparation and biosecurity measures (Satheesh Kumar et al 2013).…”

A rapid method for simultaneously diagnosing four shrimp diseases using PCR‐DNA chromatography method

“…Occurrence of dual infections has been reported (Food and Agricultural Organization, ; Otta et al., ; Pazir et al., ); hence, it is important to have a comprehensive detection to apply the needed countermeasures. To determine whether PCR‐DNA chromatography could detect all four diseases simultaneously, PCR‐DNA chromatography was performed with four kinds of plasmids (10 3 copies) with 1 μl of non‐infected shrimp DNA sample, or with pooled DNA samples from each infected shrimp.…”