Efficacy of orally administered T-705 pyrazine analog on lethal West Nile virus infection in rodents

Abstract

We describe herein that a pyrazine derivative, T-705 (6-fluoro-3-hydroxy-2-pyrazinecarboxamide), is protective for a lethal West Nile virus infection in rodents. Oral T-705 at 200 mg/kg administered twice daily beginning 4h after subcutaneous (s.c.) viral challenge protected mice and hamsters against WNV-induced mortality, and reduced viral protein expression and viral RNA in brains. The minimal effective oral dose was between 20 and 65 mg/kg when administered twice a day beginning 1 day after viral s.c. challenge of mice. Treatment could be delayed out to 2 days after viral challenge to still achieve efficacy in mice. Further development of this compound should be considered for treatment of WNV.

Figure 1

Effect of T-705 at 200 mg/kg administered orally twice daily beginning 4 hours until day 13 after s.c. injection of WNV (8.5 X 10⁴ plaque-forming units, pfu, prototypic New York 1999 isolate designated CDC 996625, Robert Lanciotti, CDC) in C57BL/6 female mice with 15 animals per group. Animal use was in compliance with the Utah State University Institutional Animal Care and Use Committee in an AAALAC-accredited facility. A.) Survival of mice, **P ≤ 0.01 using the log rank test, B.) Weight change of mice, ***P ≤ 0.001 compared to all other groups using one-way analysis of variance Kruskal-Wallis test.

Figure 2

Effect of T-705 at 200 mg/kg twice daily on WNV RNA (Morrey et al., 2006) at day 6 when administered orally twice daily beginning 4 hours after s.c. injection of WNV in C57BL/6 female mice as described in Figure 1. (*P ≤ 0.05, ***P ≤ 0.001 using one-way analysis of variance)

Figure 3

Effect of T-705 (200 mg/kg, b.i.d.) on survival A.) when administered orally twice daily beginning on day 1, 2 or 3 days for 13 day after s.c. injection of WNV in C57BL/6 female mice; or B.) when administered serial doses of T-705 beginning on day 1 as described in Figure 1. Ten animals were used per group. (*P ≤ 0.05, **P ≤ 0.01).

Figure 4

Effect of T-705 (200 mg/kg, b.i.d.) on A.) survival, B.) alkaline phosphatase detection of WNV envelope protein (Morrey et al., 2006) in brain at day 7 when administered orally twice daily beginning on day 0 for 14 days after s.c. injection with WNV in female Syrian golden hamsters (Charles River Laboratory). Fifteen animals were included in each group, wherein five animals were randomly removed on day 7 and their brains were processed for immunocytochemistry. The sections were stained with 7H2 MAb, a monoclonal antibody specific for WNV envelope, and counter-stained with hematoxylin (Morrey et al., 2006). Scale bar = 50 μm. (**P ≤ 0.01)