Repurposing an In Vitro Measles Virus Dissemination Assay for Screening of Antiviral Compounds

Abstract

Measles virus (MV) is a highly contagious respiratory virus responsible for outbreaks associated with significant morbidity and mortality among children and young adults. Although safe and effective measles vaccines are available, the COVID-19 pandemic has resulted in vaccination coverage gaps that may lead to the resurgence of measles when restrictions are lifted. This puts individuals who cannot be vaccinated, such as young infants and immunocompromised individuals, at risk. Therapeutic interventions are complicated by the long incubation time of measles, resulting in a narrow treatment window. At present, the only available WHO-advised option is treatment with intravenous immunoglobulins, although this is not approved as standard of care. Antivirals against measles may contribute to intervention strategies to limit the impact of future outbreaks. Here, we review previously described antivirals and antiviral assays, evaluate the antiviral efficacy of a number of compounds to inhibit MV dissemination in vitro, and discuss potential application in specific target populations. We conclude that broadly reactive antivirals could strengthen existing intervention strategies to limit the impact of measles outbreaks.

Keywords: antiviral; antiviral assay; fusion inhibitory peptide; measles; measles virus; pandemic response box; remdesivir.

Figure 1

(A) Schematic representation of antiviral dissemination assay. Infected cells are presented in green. (B) Dose–response curves for IVIg (blue) and ribavirin (red) in MV dissemination assay. Addition of inhibitors was six hours pre co-culture (pre, light shading), at the moment of co-culture (sim (simultaneous), medium shading) or six hours post co-culture (post, dark shading). Infection percentages were normalized to untreated cultures and errors are depicting the SEM.

Figure 2

(A) Representative dose–response curves for remdesivir (green) and ribavirin (red) in the MV dissemination assay. Addition of compounds was six hours pre-co-culture (pre, light shading), simultaneous with start of co-culture (sim, medium shading) or six hours post co-culture (post, dark shading). (B) Mean dose–response curves for remdesivir (blue and green) and ribavirin (orange and red) in MV dissemination assay comparing vaccine-strain-based (blue and orange) and wild-type-based (green and red) viruses (n ≥ 5). (C) Mean dose–response curves for remdesivir (green to blue) and ribavirin (red to orange) in MV dissemination assay comparing different clinical isolates (n = 2). (A–C) Infection percentages were normalized to untreated cultures and errors are depicting the SEM.

Figure 3

(A) Dose–response curves of three different lipopeptide classes in MV dissemination assay. Peptides depicted in green represent HRC-based lipopeptides, peptides in blue represent FIP-based lipopeptides and peptides in red represent HRC–FIP-hybrid-based peptides. Remdesivir (black) was used as a control. Infection percentages were normalized to untreated co-cultures, and errors are depicting the SEM. (B) Relative viability of co-cultures treated with different lipopeptides and infected with rMV^KSVenus(3). Shaded background depicts mean viability in infected but untreated co-cultures. Error bars depict the SEM. (C) Correlation of infection percentage and viability in infected and treated co-cultures. Shaded background depicts mean viability in infected but untreated co-cultures.

Figure 4

(A) Infection percentage reached in co-cultures treated with 160 diverse compounds at 4 µM or 20 µM evaluated at 48 hpc (left) or 72 hpc (right). Dotted lines indicate cut-off to qualify for re-screening. Overall, 21 compounds reduced MV dissemination (enlarged colored symbols, one symbol per compound). (B) Rescreening of 21 compounds and remdesivir for their inhibitory effect on MV dissemination. Dotted lines indicate compounds regarded effective. Error bars depict the SEM. (C) Relative viability of all 21 compounds and remdesivir. Dotted lines indicate compounds which were regarded effective, but proof to be cytotoxic. Shaded background depicts mean viability in infected but untreated co-culture.