Detection of Antibodies Directed Towards Snowshoe Hare Virus by PRNT<<Return to Laboratory
Serological detection of neutralizing antibodies directed towards snowshoe hare (SSH) virus by Plaque Reduction Neutralization Test (PRNT).
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 California serogroup infection. Submitted samples will first be analysed by the Viral Zoonoses Diagnostic Laboratory by SSH & JC IgM/IgG ELISA to determine if the patient has developed anti-SSH/JC antibodies. Samples that are reactive can be further analysed for the presence of neutralizing antibodies. Samples that are ELISA non reactive (negative) will not be tested by PRNT.
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, collection date of specimen, date of on-set of symptoms, and clinical and travel history of patient.
Initial screening serology such as JC ELISA must be reactive before samples will be considered for PRNT diagnostics. To demonstrate seroconversion, both acute and convalescent samples must be tested in parallel.
The PRNT is a specific assay that may be used to document the presence of neutralizing antibodies specific for a particular arbovirus like SSH virus. Serum samples are incubated with virus, and if viral neutralizing antibodies are present, they will bind to the virus and prevent viral infection of cultured cells causing a reduction in the number of plaques detected. The neutralizing titre of a sample is expressed as the reciprocal of the serum dilution at which there is a 90% reduction in the number of plaques detected.
The detection of anti-SSH virus antibody in a single sera is indicative of past or present exposure to this agent. The presence of anti-SSH virus specific IgM in a single serum sample is consistent with an acute infection to this agent 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.
14 calendar days after the completion of ELISA testing.
- WHO. 2007. Guidelines for plaque reduction neutralization testing of human antibodies to dengue viruses.