A sensitive cell-based assay for the detection of residual infectious West Nile virus

• Published in: Vaccine 2007-09, Vol.25 (39), p.6872-6881
• Main Authors: Koldijk, M.H, Bogaards, J.A, Kostense, S, de Vocht, M, Gijsbers, L, ter Haak, M, Ophorst, C, Brakenhoff, J.P.J, Weverling, G.J, Guichoux, J.Y, UytdeHaag, F, Lewis, J, Goudsmit, J, Marzio, G
• Format: Article
• Language: English
• Subjects: Allergy and Immunology; Animals; Animals, Suckling; Assay; Biological and medical sciences; Cell culture; Cell Line; Cercopithecus aethiops; Dilution; Disease Models, Animal; Encephalitis; Fundamental and applied biological sciences. Psychology; Immunization; Inactivation; Infections; Mice; Mice, Inbred C3H; Microbiology; Miscellaneous; Propiolactone - pharmacology; Vaccines; Vaccines, Inactivated; Vector-borne diseases; Vero Cells; Viral infections; Virology; Virus; Virus Inactivation; West Nile Fever - mortality; West Nile Fever - virology; West Nile virus; West Nile virus - drug effects; West Nile virus - isolation & purification; West Nile virus - pathogenicity; West Nile virus - physiology; West Nile Virus Vaccines
• ISSN: 0264-410X; 1873-2518
• DOI: 10.1016/j.vaccine.2007.07.011

Abstract Ensuring complete viral inactivation is critical for the safety of vaccines based on an inactivated virus. Detection of residual infectious virus is dependent on sensitivity of the assay, sample volume analyzed and the absence of interference with viral infection. Here we describe the development and qualification of a sensitive cell-based assay for the detection of residual infectious West Nile Virus (WNV). The results of the assay are in good agreement with the assumption that at low concentrations the number of infectious units in relatively small samples follows a Poisson distribution. The assay can detect 1 infectious unit with a confidence of 99%, provides statistical controls for interference and can easily be scaled up to test large amounts of vaccine material. Furthermore, we show equivalence in sensitivity between the cell-based assay and an in vivo assay for detection of infectious WNV. Finally, the assay has been used for successful release testing of clinical lots of inactivated WNV vaccine. Given the principle and generic setup of the method we envision broad applicability to the detection of very low concentrations of infectious virus.