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Related Concept Videos

Arboviral Encephalitis01:25

Arboviral Encephalitis

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Arboviral encephalitis refers to brain inflammation caused by arthropod-borne viruses, particularly those transmitted through mosquito vectors. Among these, West Nile virus (WNV), a member of the Flaviviridae family, is a significant public health concern. WNV is an enveloped, positive-sense, single-stranded RNA virus. Human infection typically begins when an infected mosquito introduces the virus into the dermis during feeding. The primary transmission cycle involves birds as amplifying hosts...
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Related Experiment Video

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Optimization of a Quantitative Micro-neutralization Assay
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Labile serum factor and its effect on arbovirus neutralization.

W A Chappell, D R Sasso, R F Toole

    Applied Microbiology
    |January 1, 1971
    PubMed
    Summary

    A labile serum factor (LSF) in human blood enhances the neutralization of several encephalitis viruses. This factor remains active after freezing but is destroyed by heat, highlighting the need for careful serum preparation in research.

    Area of Science:

    • Virology
    • Immunology
    • Biochemistry

    Background:

    • Encephalitis viruses pose significant public health threats.
    • Viral neutralization assays are crucial for understanding immune responses.
    • The role of serum factors in viral neutralization requires further elucidation.

    Purpose of the Study:

    • To investigate the role of a labile serum factor (LSF) in human serum and plasma in enhancing viral neutralization.
    • To characterize the stability and properties of LSF.

    Main Methods:

    • Neutralization assays were performed using Sindbis, Venezuelan equine encephalitis, Eastern equine encephalitis, Western equine encephalitis, and St. Louis encephalitis viruses.
    • Human serum and plasma were subjected to various storage conditions (temperature, freeze-thaw cycles) and treatments (heating, dialysis).

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  • The effect of LSF on immune mouse and rabbit sera was assessed.

    • Main Results:

    • Human serum and plasma demonstrated LSF activity, enhancing viral neutralization even at dilutions of 1:8 and 1:16.
    • LSF activity was retained after storage at -20°C or -56°C and was unaffected by repeated freeze-thaw cycles.
    • LSF activity was completely abolished by heating at 56°C for 5 minutes and was not restored by guinea pig complement.
    • LSF activity showed no species specificity, enhancing neutralization by both mouse and rabbit immune sera.
    • The components responsible for LSF activity were not dialyzable.

    Conclusions:

    • A heat-labile, non-dialyzable factor in human serum and plasma significantly enhances the neutralization of several important encephalitis viruses.
    • LSF is stable under freezing conditions but sensitive to heat, necessitating careful handling and pretesting of serum sources.
    • The findings suggest LSF is a crucial, yet previously unrecognized, component in antiviral immunity.