Hantavirus infection laboratory findings
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Furqan M M. M.B.B.S[2]
Overview
Diagnosis of hantavirus infection is usually made by a positive serological test result. Evidence of viral antigen in tissue by immunohistochemistry, or the presence of amplifiable viral RNA sequences in blood or tissue, with a compatible history of HPS, is considered diagnostic for HPS.
Laboratory Findings
Serologic assays
- The most effective and widely used test for hantavirus screening is the enzyme-linked immunosorbent assay, which detects IgM antibodies.Enzyme-linked immunosorbent assay (ELISA) detects IgM antibodies to Sin Nombre virus (SNV). An IgG test can be used in conjunction with the IgM-capture test.
- A Western blot assay using recombinant antigens and isotype-specific conjugates for IgM-IgG differentiation has also been developed and its results are generally in agreement with those of the IgM-capture format.
- Also in use is a rapid immunoblot strip assay (RIBA), an investigational prototype assay to identify serum antibody to recombinant proteins and peptides specific for SNV and other hantaviruses.
Isolation
Isolation of hantaviruses (see below) from human sources is difficult, and the viruses causing HPS seem to be no exception to this rule. To date, no isolates of SNV-like viruses have been recovered from humans, and therefore virus isolation is not a consideration for diagnostic purposes.
Immunohistochemistry (IHC)
IHC testing of formalin-fixed tissues with specific monoclonal and polyclonal antibodies can be used to detect hantavirus antigens and has proven to be a sensitive method for laboratory confirmation of hantaviral infections. IHC has an important role in the diagnosis of HPS in patients from whom serum samples and frozen tissues are unavailable for diagnostic testing and in the retrospective assessment of disease prevalence in a defined geographic region.
Polymerase Chain Reaction (PCR)
Reverse transcriptase-PCR (RT-PCR) can be used to detect hantaviral RNA in fresh frozen lung tissue, blood clots, or nucleated blood cells. However, RT-PCR is very prone to cross-contamination and should be considered an experimental technique. Differences in viruses in the United States complicate the use and sensitivity of RT-PCR for the routine diagnosis of hantaviral infections.