DAO 69:129-136 (2006)  -  doi:10.3354/dao069129

Low impact of infectious hypodermal and hematopoietic necrosis virus (IHHNV) on growth and reproductive performance of Penaeus monodon

Boonsirm Withyachumnarnkul1,2,*, Kanokporn Chayaburakul3, Supak Lao-Aroon4, Pornthep Plodpai4, Kallaya Sritunyalucksana2, Gary Nash5

1Department of Anatomy, and 2Centex Shrimp, Chalerm Prakiat Building, 4th Floor, Faculty of Science, Mahidol University, Rama 6 Rd, Bangkok 10400, Thailand
3Anatomy Unit, Faculty of Science, Rangsit University, Muang-Ake, Pathumtani 12000, Thailand
4Shrimp Culture Research Center, Charoen Pokphand Foods Company (Public), Nakorn Srithamaraj 80170, Thailand
5National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathumtani 12000, Thailand

ABSTRACT: No controlled studies on the effect of infectous hypodermal and necrosis virus (IHHNV) on Penaeus monodon have been previously reported. Here we describe domesticated P. monodon that became positive for IHHNV and other viruses at variable levels of prevalence during cultivation in 16 open-air, earthen ponds. These were stocked with domesticated postlarvae (PL) that tested negative for 7 shrimp viruses including IHHNV at 6% prevalence in 3 checks using polymerase chain reaction (PCR) methods. These PL were derived from domesticated female broodstock that individually tested negative for the same viruses. At 4 mo of culture, the shrimp in some ponds without obvious mortality tested positive by PCR methods for IHHNV and 3 other viruses at variable levels of maximum estimated prevalence (MEP). Stained tissue sections showed no lesions typical of IHHNV, but in situ hybridization tests with an IHHNV-specific DNA probe were positive. There was no significant difference in mean body weight (i.e. ca. 25 g) between shrimp groups positive or negative for IHHNV. Similar results were obtained with IHHNV negative and positive adults at 1 yr. Adults that individually tested negative for all 7 viruses and some that tested lightly positive for IHHNV were bred for the next generation. There were no significant differences in the number of eggs (>600000) and nauplii (ca. 300000) produced by females negative and positive for IHHNV. From these females, 11/49 (22%) IHHNV PCR-positive PL batches were obtained from PCR-negative spawners, while 8/11 (73%) were obtained from IHHNV PCR-positive spawners. The results suggested that IHHNV infection can be transmitted vertically but does not seriously retard growth of P. monodon or affect fecundity of lightly infected broodstock.

KEY WORDS: Penaeus monodon · Domestication · Broodstock · IHHNV · PCR · Reproduction · Growth

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