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, 25 (1), 63-8

Association of Dual Viral Infection With Mortality of Pacific White Shrimp (Litopenaeus Vannamei) in Culture Ponds in India

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Association of Dual Viral Infection With Mortality of Pacific White Shrimp (Litopenaeus Vannamei) in Culture Ponds in India

S K Otta et al. Virusdisease.

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.

Keywords: Dual viral infection; India; Litopenaeus vannamei; Shrimp mortality.

Figures

Fig. 1
Fig. 1
PCR detection of WSSV and IHHNV by different sets of primers in representative samples from different farms of Tamil Nadu, India. Lanes 18 L. vannamei samples from different farms. Lane 9 negative control, Lane 10 positive control, Lane 11 100 bp molecular weight marker
Fig. 2
Fig. 2
PCR detection of shrimp viruses by IQ 2000 kit in representative samples from different farms of Tamil Nadu, India. Lanes 1–8: L. vannamei samples from different farms Lane 9: Negative control, Lane 10–12: Positive controls with different copy numbers to show the degree of infection ( highest degree with 3 bands, moderate with 2 and lowest with 1 band), Lane 13: IQ 2000 Molecular weight Marker
Fig. 3
Fig. 3
Sections of gill tissue from infected L. vannamei showing eosinophilic (white arrow) and basophilic (black arrow) inclusion bodies suggestive of WSSV infection (Magnification ×100). Bar 15 μm
Fig. 4
Fig. 4
Sections of gill tissue of infected L.vannamei showing Cowdry type A inclusion bodies (blocked arrow) suggestive of IHHNV infection (Magnification ×100). Bar 15 μm

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