A simple strip-test kit for white spot syndrome virus (WSSV) detection was developed
using monoclonal antibody W29 (against the VP28 structural protein) conjugated with colloidal gold
as the detector antibody. A rabbit anti-recombinant VP28F118 (rVP28) protein antibody in combination
with a W28 monoclonal antibody was used as the capture complex at the test line (T), and goat
anti-mouse IgG antibody (GAM) was used as the capture antibody at the control line (C). For evidence,
the ready-to-use strip was kept in a plastic case and stored in a desiccated plastic bag. A sample
volume of 100 μl gill homogenate in application buffer was applied to the sample chamber at one
end of the strip and allowed to flow by chromatography through the nitrocellulose membrane to the
other end. In test samples containing WSSV, the virus bound to the monoclonal antibody conjugated
with colloidal gold and the resulting complex was captured by the antibodies at T to give a reddishpurple
band. Any unbound monoclonal antibody conjugated with colloidal gold moved across T to be
captured by the GAM and formed a band at C. In samples without WSSV or with WSSV below the
limit of detection of the kit, only the band at C was seen. This method was 4 times less sensitive than
dot blotting, and about 2 000 000 times less sensitive than 1-step PCR. Nonetheless, it could be used
to screen individual shrimp or pooled shrimp samples to confirm high levels of WSSV infection or
WSSV disease outbreaks. The beneficial features of this kit are that simple, convenient and quick
results can be obtained without the requirement of sophisticated tools or special skills.