The Australian red claw crayfish (RCC), Cherax quadricarinatus was introduced in Thailand more than two decades
ago for culture in freshwater areas where marine penaeid shrimp are also frequently farmed. Despite
many reports of various diseases that occur in RCC in Australia (both from natural habitats and from farms),
there have been no reports of its diseases when farmed in Thailand. Our recent study on RCC cultured in
Thailand revealed that it is susceptible to WSSV infection and that it can transmit the virus to native shrimp
species such as the black tiger shrimp (Penaeus monodon). Thus, we decided to continue by testing whether
RCC were also susceptible to endemic yellow head virus (YHV) and also capable of transmitting it to black
tiger shrimp (BTS). Using three different exposure methods (injection, feeding and cohabitation) with test
RCC, we obtained no YHV pathology or positive immunoreactions using monoclonal antibodies against all 3
structural proteins of YHV. By contrast, a standard RT-PCR assay targeting the RdRp gene of YHV with RNA extracted
from the experimentally exposed red claw did give positive results. In addition, BTS that tested negative
for YHV and were then cohabitated (separated by a plastic net) with RT-PCR positive RCC became infected with
YHV and died, exhibiting the severe histopathology typical of yellow head disease. Thiswas confirmed by strong
positive immunohistochemical reactions for YHV and positive RT-PCR results. These results suggested that the
experimentally exposed RCC were susceptible to YHV infection at sufficient level to allow transmission to BTS
but not sufficient to allow detection by the standard histological methods currently used.
The Australian red claw crayfish (RCC), Cherax quadricarinatus was introduced in Thailand more than two decadesago for culture in freshwater areas where marine penaeid shrimp are also frequently farmed. Despitemany reports of various diseases that occur in RCC in Australia (both from natural habitats and from farms),there have been no reports of its diseases when farmed in Thailand. Our recent study on RCC cultured inThailand revealed that it is susceptible to WSSV infection and that it can transmit the virus to native shrimpspecies such as the black tiger shrimp (Penaeus monodon). Thus, we decided to continue by testing whetherRCC were also susceptible to endemic yellow head virus (YHV) and also capable of transmitting it to blacktiger shrimp (BTS). Using three different exposure methods (injection, feeding and cohabitation) with testRCC, we obtained no YHV pathology or positive immunoreactions using monoclonal antibodies against all 3structural proteins of YHV. By contrast, a standard RT-PCR assay targeting the RdRp gene of YHV with RNA extractedfrom the experimentally exposed red claw did give positive results. In addition, BTS that tested negativefor YHV and were then cohabitated (separated by a plastic net) with RT-PCR positive RCC became infected withYHV and died, exhibiting the severe histopathology typical of yellow head disease. Thiswas confirmed by strongpositive immunohistochemical reactions for YHV and positive RT-PCR results. These results suggested that theexperimentally exposed RCC were susceptible to YHV infection at sufficient level to allow transmission to BTSbut not sufficient to allow detection by the standard histological methods currently used.
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