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Detection of Antibodies Directed Towards Yellow Fever Virus by PRNT

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Requisition Forms

Reference Details

Description:

Serological detection of neutralizing antibodies directed towards yellow fever virus (YF) virus by Plaque Reduction Neutralization Test (PRNT).

Test Category:
Serology
Pathogen:
Yellow Fever virus (YF)
Laboratory:
Illnesses and Diseases:
  • Yellow fever
Specimen:

Serum. Minimum volume of 250 ml required.

Collection Method:

Collect blood in serum separator 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.

Patient Criteria:

Suspected YF infection and relevant travel history.

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, and clinical and travel history of patient.

Comments:

This is not a routine test. Please contact the Viral Zoonoses Diagnostic Laboratory before sending specimens. Initial screening serology such as YF virus ELISA or YF virus IFA must be reactive before samples will be considered for PRNT diagnostics.

Methods and Interpretation of Results:

Antibodies directed towards members of the flavivirus genus (dengue, West Nile virus, yellow fever) can cross react significantly in some serological assays such as the ELISA and IFA. The PRNT is a more specific assay and can be used to document the presence of serum antibodies specific for a particular flavivirus. 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. If the patient has experienced more than one flavivirus infection, cross reactive results could in fact yield uninterpretable results with this assay despite increased specificity.

1. Due to the cross-reactive nature of flavivirus antibody, the detection of flavivirus IgG (Eg. Yellow fever, dengue, etc.) in a single sera is indicative of past or present exposure to this agent, or a related agent from the same virus genus. The presence of flavivirus 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 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.
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, or detection of arboviral antigen or nucleic acid in a clinical specimen would constitute firm evidence of viral association with illness and provide "confirmed case" status.
Turnaround Time:

14 calendar days after the completion of YF virus IFA or YF virus ELISA testing.

Contact:
Phone #: (204) 789-6071
Fax: (204) 789-2082
References:
  1. WHO. 2007. Guidelines for plaque reduction neutralization testing of human antibodies to dengue viruses
Guidelines: