Dr. Chu-Fang Lo

Institute of Zoology, National Taiwan University, Taipei,Taiwan, ROC

Corresponding e-mail: gracelow@ntu.edu.tw

Host Response: Antiviral Proteins 

Some shrimp are able to survive a WSSV disease outbreak. In the defense related cells (hepatopancreatic cells and hemocytes) of virus resistant shrimp, Suppression Subtractive Hybridization (SSH) has shown differential gene expression with respect to normal shrimp. At least 60 peptides that may have antiviral properties were up-regulated in the WSSV-resistant shrimp. These up-regulated proteins include not only redox-related factors, and plasma defense proteins (eg. C-type lectin), translational controlled tumor protein (TCTP), but also an interferon-like protein and an associated downstream (2’-5’) oligo (A) synthetase-like protein. Again, this has obvious implications for the capabilities and mechanisms of the invertebrate immune system. These data provide very good bases for future studies on shrimp antiviral mechanisms

Host Response: Cellular Pathways that Support Virus Replication

Alongside the host cells’ virions anti-viral mechanisms, there are also pathways which can be exploited by the virus and which are of benefit to the virus. To investigate these pathways, our first step was to use 2D proteomic analysis to identify differentially expressed genes in one of the main WSSV target cells (stomach cells) in Litopenaeus vannamei before and after infection. We identified over 70 proteins, many of which are involved in important cellular functions. Interestingly, some of the genes that were up-regulated in resistant shrimp were down-regulated in the WSSV-challenged L. vannamei, so a coherent picture is already beginning to emerge. Obviously, future studies will want to investigate if and how these genes are related to WSSV resistance.

Conclusions

The threat posed by WSSV and other shrimp viruses continues to overshadow the aquaculture industry. Further, this threat is ever-changing, and if we continue to culture shrimp intensively, then new outbreaks of viral diseases will almost certainly occur. To effectively counter this “moving target” and stay one step ahead of both established and emerging crustacean viruses, then in addition to quarantine and movement control, we also need to understand the pathogenesis of shrimp viruses at the organism, cellular and molecular levels.  Basically, the more we know about these viruses, the better prepared we are to deal with the current threat and any future threats that emerge. It should be pointed out that to support this work, proteomics and other global analysis technologies are very useful tools, and the expansion of EST databases for functional genomic studies is also critical. As additional benefit, our increasing knowledge of WSSV and of its host/virus interactions means that the WSSV/shrimp model may be very useful for investigating crustacean immunity.

Reference

1. Chen, L.L., Wang, H.C., Huang, C.J., Peng, S.E., Chen, Y.G., Lin, S.J., Chen, W.Y., Dai, C.F., Yu, H.T., Wang, C.H., Lo, C.F. and Kou, G.H.. 2002. Virology. 301:136-147.

2. He, N., Qin, Q., and Xu, X.. 2005. Antiviral Res. 66: 39-45.

3. Leu, J.H., Tsai, J.M., Wang, H.C., Wang, A.H-J., Wang, C.H., Kou, G.H. and Lo, C.F.. 2005. J. Virol. 79:140-149.

4. Liu, W.J., Chang, Y.S., Wang, C.H., Kou, G.H. and Lo, C.F.. 2005. Virology. 334:327-41.

5. Pan, D., He, N., Yang, Z., Liu, H., Xu, X.. 2005. Dev. Comp. Immunol. 29:103-112.

6. Tsai, J.M., Wang, H.C., Leu, J.H., Hsiao, H.H., Wang, A.H-J., Kou, G.H. and Lo, C.F.. 2004. J. Virol. 78:11360-11370.

7. Vlak, J.M., Bonami, J.R., Flegel, T.W., Kou, G.H., Lightner, D.V., Lo, C.F., Loh P.C. and Walker P.W.. 2004. Nimaviridae. In: VIIIth Report of the International Committee on Taxonomy of Viruses (C.M. Fauquet, M.A. Mayo, J. Maniloff, U. Desselberger and L.A.Ball, Eds.), Elsevier, p. 187-192.

8. Witteveldt, J., Cifuentes, C.C., Vlak, J.M., van Hulten, M.C.. 2004. J. Virol. 78:2057-61.

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