Diagnostic test for West Nile virus

A method for detecting a WNV infection in a biological specimen comprising the steps of:

• (a) obtaining a suspension of microspheres each covalently attached via its carboxylated surface to a substantially pure WNV NS5 protein having a native conformation or non-denatured structure wherein the WNV NS5 protein is specifically reactive with anti-WNV antibodies;
• (b) performing a microsphere immunoassay;
• (c) obtaining a result indicating either the presence or absence of an anti-WNV antibody;
• wherein the presence of an anti-WNV antibody indicates a WNV infection.

A method for rapid detection of a WNV infection in an animal susceptible of infection by said WNV, comprising the steps of:

• (a) contacting a biological sample of said animal comprising anti-WNV antibodies with a microsphere suspension, each microsphere covalently attached via its carboxylated surface to a substantially pure WNV NS5 protein having a native conformation or non-denatured structure whereby each WNV NS5 protein is reactive to said anti-WNV antibodies,
• (b) incubating the microsphere suspension under conditions sufficient to promote the binding of said anti-WNV antibodies to the WNV NS5 protein,
• (c) contacting the microsphere suspension with a detection reagent capable of detecting the anti-WNV antibody,
• (d) detecting the detection reagent,
• wherein detection of the detection reagent indicates the presence of said anti-WNV antibody in said biological sample.

A method for immunochromatographically testing for a WNV infection in an animal susceptible to said infection, comprising the steps of:

• (a) contacting a biological sample comprising anti-WNV antibodies with a suspension of WNV NS5-coated microspheres, wherein each microsphere is covalently attached via its carboxylated surface to a substantially pure WNV NS5 protein to form a reaction mixture under conditions sufficient to promote binding of the anti-WNV antibodies to the WNV NS5-coated microspheres,
• (b) placing the reaction mixture at the proximal end of the membrane strip having a proximal end, a distal end, and a plurality of zones each comprising secondary antibodies coupled thereto,
• (c) incubating the membrane strip under sufficient conditions to promote the movement of the reaction mixture towards the distal end, said conditions being also sufficient to promote the binding of the microparticles to said secondary antibodies coupled to the membrane strip vis-à-vis interactions between said secondary antibodies and the anti-WNV antibodies,
• (d) washing from the membrane strip any unbound microparticles, and
• (e) detecting bound microparticles, wherein bound microparticles indicates a WNV infection in said animal.