A profound
effect of hyperthermia on survival of Litopenaeus vannamei juveniles
infected with White spot Syndrome Virus
O.M. Vidal, C.B. Granja, F. Aranguren, J.A. Brock, M.
Salazar-2001
Journal of the World Aquaculture Society, 32(4):
364-372 (from Current Contents)
Abstract:
This study was conducted to examine the effect of
increasing seawater temperature on White Spot Syndrome Virus (WSSV)
infection in juvenile Pacific White shrimp (Litopenaeus vannamei). Infection
by WSSV was achieved using two methods, intramuscular injection and per os
(oral) administration. Forty injected and 20 per os infected animals were
kept in heated tanks at 32.3 +/- 0.8 C, and the same number of WSSV infected
animals were maintained in tanks at ambient temperature (25.8 +/- 0.7 C).
Despite the route of exposure, there were no survivors among the animals
kept at ambient temperature; whereas, in heated tanks the survival of the
WSSV infected juvenile shrimp was always above 80%, suggesting the existence
of a beneficial effect from hyperthermia that mitigated the progression of
WSSV disease. Moreover, this beneficial effect was not attributable to viral
inactivation. Infected animals kept at 32 C had histologically detectable
lymphoid organ spheroids suggestive of a chronic viral infection but were
PCR negative (hemolymph) for WSSV. These findings might be related to low
viral replication in WSSV-infected shrimp held at the higher environmental
temperature. When the WSSV-infected shrimp were transferred from 32 C to
ambient temperature, the mortality, from WSSV ensued and was always 100%.
Although the mechanism related to the beneficial effect of heating was not
determined, our results indicate that increasing the water temperature
modifies dramatically the natural history of the WSSV disease and the
survival curves of WSSV-infected juvenile Pacific White shrimp.
(Corp
Ctr Invest Acuicultura Colombia CENIACUA, Carretera 8 96-60, Bogota,
Colombia)