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Detection of Antibodies Directed Towards Cache Valley Virus by PRNT

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Requisition Forms

Reference Details


Serological detection of neutralizing antibodies directed towards Cache Valley virus by a plaque reduction neutralization test (PRNT).

Test Category:
Cache Valley virus
Illnesses and Diseases:
  • Encephalitis

Serum. Minimum volume of 250 µl required.

Collection Method:

2 mL screw cap tubes.

Specimen Processing, Storage and Shipping:

Store samples refrigerated until shipped for testing. Ship samples on cold pack, or with wet or dry ice.

Transportation of Dangerous Goods:

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.

For additional guidance on the transport of infectious substances in other languages, please click on the link below.


Patient Criteria:

Suspected Cache Valley virus infection.

Accompanying Documentation:

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, type of specimen, and clinical and travel history of patient.


This is not a routine test. Please contact the Viral Zoonoses Laboratory before sending specimens.

Methods and Interpretation of Results:

The PRNT is a specific assay that may be used to document the presence of neutralizing antibodies specific for a particular arbovirus like Cache Valley 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.

1. The detection of Cache Valley IgG neutralizing antibody in a single sera is indicative of past or present exposure to this agent. However, a 4 fold rise or greater in neutralizing antibody titre is required to document a "confirmed case" of infection with associated illness.

2. There is increasing evidence for IgM persistence in blood/serum for up to a year or more after arbovirus (Eg. 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.

3. 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.

Turnaround Time:

21 calendar days.

Phone #: (204) 789-6097 or (204) 789-2106
Fax: (204) 789-2082
  1. WHO. 2007. Guidelines for plaque reduction neutralization testing of human antibodies to dengue viruses
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