Standardization of a plaque assay for Lassa virus

Area of Science:

• Virology
• Immunology
• Public Health

Background:

• The plaque reduction neutralization test (PRNT) is standard for arenavirus serology but faces challenges with LCM and Lassa viruses.
• Conflicting data exists on the PRNT's reliability and efficacy for Lassa virus detection.

Purpose of the Study:

• To evaluate the Lassa virus plaque assay and its suitability for PRNT.
• To assess PRNT's efficacy in determining serum potency for Lassa fever serotherapy.
• To investigate PRNT's role in passive immunization for Lassa fever treatment.

Main Methods:

• Validated Lassa virus plaque assay against Cooper's [1961] criteria.
• Utilized native, non-inactivated serum for reliable antibody titer determination.
• Employed constant serum-varying virus (CS-VV) and constant virus-varying serum (CV-VS) PRNT techniques.

Main Results:

• The Lassa virus plaque assay met established criteria for plaque techniques.
• Lassa virus plaques were clearly defined and measurable within 3-5 days in Vero cell cultures.
• Native, non-inactivated serum is essential for reproducible PRNT results.

Conclusions:

• The plaque assay is a suitable method for Lassa virus characterization.
• PRNT, using native serum and specific methods, reliably determines Lassa virus antibody titers.
• This validates PRNT for assessing serum potency in Lassa fever serotherapy.