The study of binding between VP28 of WSSV and Rab7 of giant tiger prawn Penaeus monodon
Date Issued
2008
Date
2008
Author(s)
Sun, Hong
Abstract
White spot syndrome virus (WSSV) was first emerged in south Asia in the early 1990’s. It has a wide range of hosts among crustaceans and causes up to 100% mortality within 7 to 10 days in cultured shrimps. It was spread out all over the world rapidly. Until now, white spot syndrome has become one of the most serious viral diseases of cultivated shrimp and causes considerable economic losses to the shrimp farming industry worldwide. Currently, there are about 40 structural proteins of WSSV being identified, of which 22 are envelope proteins constructing the infection-related structure. VP28 and VP26 are the most abundant structural proteins observed in the viral envelope, accounting for approximately two-thirds of the envelope proteins. Furthermore, in neutralization experiments, anti-VP28 polyclonal or monoclonal antibody such as AP-1 can protect shrimp from WSSV infection and reduce mortality, therefore it has been considered to be the most important viral protein in WSSV infection. In order to find out the VP28 receptor on shrimp cell, E. coli expressed VP28 was used to run binding test in Penaeus monodon hemocyte in pervious study. The Rab7 protein was thought to directly bind VP28. However, there are some problems about this study. First, E. coli belongs to prokaryotes which lack posttranslational modification as in eukaryotes, hence there would have some structural differences between VP28 of WSSV and that expressed by E. coli. Second, in previous study, Rab7 does not involve in vesicle formation and inner transportation in yeast, vero cell and HeLa cell, and even does not exist on cell membrane. In addition Rab7 is highly conserved in function domain and gene sequence among species. Therefore, the probability is very low for Rab7 to bind VP28 on shrimp cell membrane. In this study, VP28 gene was homologous recombined to the baculovirus and infected insect cell line (sf-9) to express VP28 viral protein. The E. coli expressed Rab7 and anti-VP28 monoclonal antibody, AP-1, were used for compete enzyme-link immunosorbent assay (Compete ELISA). Results showed that Rab7 did not compete with AP-1 on binding VP28. The survival rate of AP-1 treated shrimps was significantly higher than those AP-1 untreated ones after WSSV challenge. Taken together, Rab7 may not directly involve in WSSV infection on the plasma membrane, and the role of Rab7 needs further studies.
Subjects
WSSV
VP28
Rab7
Giant tiger prawn
Receptor
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