Detection of IgM Antibodies Directed Towards West Nile Virus by ELISA<<Return to Laboratory
Accredited by the Standards Council of Canada to Laboratory no. 594 (ISO/IEC 17025)
Serological detection of IgM antibodies directed towards West Nile virus (WNV) by In-House MAC ELISA.
- West Nile encephalitis
Serum. Minimum volume of 250 µl required.
2 mL screw cap tubes.
Store samples refrigerated or frozen until shipped for testing. Ship frozen samples on dry ice, and refrigerated samples on wet ice
Shipping of specimens shall be done by a TDG certified individual in accordance with TDG regulations. For additional information regarding classification of specimens for the purposes of shipping, consult either Part 2 Appendix 3 of the TDG Regulations or section 3.6.2 of the IATA Dangerous Goods Regulations as applicable.
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Suspected West Nile virus infection.
Completed Viral Zoonoses requisition including sender laboratory name, address and telephone number. Patient name and / or identifier (specimen reference number), date of birth, test(s) requested, date of on-set of symptoms, and clinical and travel history of patient.
All WNV diagnostic samples are tested by both IgM and IgG ELISA to increase the clinical sensitivity.
Due to the cross-reactive nature of flavivirus antibody, the detection of anti-flavivirus IgG (i.e. dengue, Yellow Fever etc.) in a single serum sample is indicative of past or present exposure to this agent, or a related agent from the same virus genus. The presence of anti-WNV specific IgM in a single serum sample is consistent with an acute infection to this agent (or a related flavivirus, note that flavivirus IgM serological detection procedures are more specific than IgG serology for this genera of arboviruses) and meets the criteria for a "probable case". However, a 4-fold rise or greater in neutralizing antibody titre, or an IgG or IgM seroconversion in paired sera, is required to document a "confirmed case" of infection with associated illness.
There is increasing evidence for IgM persistence in blood/serum for up to a year or more after arbovirus (i.e members of the flavivirus, alphavirus, and bunyavirus arthropod borne virus groups) exposure. Thus, detection of IgM by itself may not always be a confirmation of acute infection.
Isolation of an arbovirus, detection of specific antibody by plaque reduction neutralization assay or detection of nucleic acid by Real Time RT-PCR in a clinical specimen would constitute firm evidence of viral association with illness and provide "confirmed case" status.
15 Calendar days.
- Martin, D.A., Muth, D.A, Brown, T., Johnson, A.J., Karabatsos, N., and Roehrig, J.T. Standardization of immunoglobulin M capture enzyme-limked immunosorbent assays for routine diagnosis of arboviral infections. J. Clin. Micro. 2000; 38: 1823-1826.