(A) Western blot analysis. Reactivity of six anti-WNV MAbs with denatured antigen. A MAb against influenza virus was used as negative control. M: protein molecular weight markers. Lane 1: sera from WNV infected horse. Lane 2: sera from WNV vaccinated horse. Lane 3: sera from WNV negative horse. (B) Detection of WNV and USUV-infected cells using IPMA (10X). WNV-infected Vero cells stained with MAb 3B2 (1) and 2A8 (2). USUV-infected VERO cells stained with MAb 3B2 (3) and 2A8 (4).