Quantification of Neutralizing Antibodies of Tick-Borne Viruses Using Focus Neutralization Assays

Tick-borne flaviviruses, such as Powassan virus (POWV) or Deer tick virus (DTV), can elicit robust humoral responses in animal models of disease (Hermanceet al., PLoS Negl Trop Dis 14(6):e0008359, 2020; Stone et al., Cell Rep 38(7):110388, 2022; Reynolds et al., Comp Med 67:232-241, 2017). Several aspects of humoral immunity to tick-borne flaviviruses are unknown; however, convalescent serum can offer partial protection against a POWV challenge naïve immune-competent animals (Stone et al., Cell Rep 38(7):110388, 2022). Accurately quantifying the neutralizing titers of protective antibodies allows us to determine the effectiveness of virus neutralization of a given sample. Understanding the efficacy of convalescent sera or antibody titers post-infection or vaccination facilitates identifying a potential correlate of protection.