ABSTRACTNo antiviral drugs currently exist for the treatment of enterovirus infections, which are often severe and potentially life threatening. Molecular screening of small molecule libraries identified fluoxetine, a selective serotonin reuptake inhibitor, as a potent inhibitor of coxsackievirus replication. Fluoxetine did not interfere with either viral entry or translation of the viral genome. Instead, fluoxetine and its metabolite norfluoxetine markedly reduced the synthesis of viral RNA and protein. In view of its favorable pharmacokinetics and safety profile, fluoxetine warrants additional study as a potential antiviral agent for enterovirus infections.

Antiviral drugs do not currently exist for the treatment of enterovirus infections, which are often severe and potentially lifethreatening. We conducted high-throughput molecular screening and identified a structurally diverse set of compounds that inhibit the replication of coxsackievirus B3, a commonly encountered enterovirus. These compounds did not interfere with the function of the viral internal ribosome entry site or with the activity of the viral proteases, but they did drastically reduce the synthesis of viral RNA and viral proteins in infected cells. Sequence analysis of compound-resistant mutants suggests that the viral 2C protein is targeted by most of these compounds. These compounds demonstrated antiviral activity against a panel of the most commonly encountered enteroviruses and thus represent potential leads for the development of broad-spectrum anti-enteroviral drugs.

Infection by the neurotropic JHM strain of mouse hepatitis virus (JHMV) results in an acute encephalomyelitis associated with demyelination. T cells are critical in controlling viral replication, but also contribute to central nervous system (CNS) pathogenesis. To reveal a role for innate effectors in anti-viral immunity and neurological disease, JHMV pathogenesis was studied in mice deficient in interleukin-15 (IL-15-/-) and natural killer (NK) cells. Clinical disease, CNS inflammation and demyelination in infected IL-15-/- mice were similar to wild-type mice. Despite the absence of NK cells and suboptimal CD8+ T cell responses, IL-15-/- mice controlled JHMV replication as efficiently as wild-type mice. Similar kinetics of class I and class II upregulation on microglia further suggested no role of NK cells in regulating major histocompatibility complex (MHC) molecule expression on resident CNS cells. IL-15 and NK cells thus appear dispensable for anti-viral immunity and CNS pathogenesis during acute JHMV infection.

A series of novel pyrazolopyridine compounds have been designed and prepared by a general synthetic route. Their activities against the replication of poliovirus-1, EV-A71, and CV-B3 enteroviruses were evaluated. The comprehensive understanding of the structure-activity relationship was obtained by utilizing the variation of four positions, namely, N1, C6, C4, and linker unit. From the screened analogues, the inhibitors with the highest selectivity indices at 50% inhibition of viral replication (SI) were those with isopropyl at the N1 position and thiophenyl-2-yl unit at C6 position. Furthermore, the C4 position offered the greatest potential for improvement because many different N-aryl groups had better antiviral activities and compatibilities than the lead compound JX001. For example, JX040 with a 2-pyridyl group was the analogue with the most potent activity against non-polio enteroviruses, and JX025, possessing a 3-sulfamoylphenyl moiety, had the best activity against polioviruses. In addition, analogue JX037, possessing a novel pyrazolopyridine heterocycle, was also shown to have good antienteroviral activity, which further enlarges the compound space for antienteroviral drug design.

Memory CD8+ T cells are comprised of CD122hi IL-15-dependent and CD122lo IL-15-independent subsets. Induction and retention of IL-15-independent memory CD8+ T cells was assessed in IL-15-/- and wild-type (wt) mice immunized with recombinant vaccinia virus (rVV) or Sindbis virus (rSIN) vectors expressing the identical foreign epitope. Both vectors induced epitope-specific CD8+ T cell expansion and function, independent of IL-15. Similar kinetics of rVV clearance confirmed effective CD8+ T cell function in IL-15-/- mice. CD44hi CD122hi CD8+ T cells, mainly of the CD62L-/lo phenotype, increased more dramatically and declined more rapidly in IL-15-/- mice, independent of the vector. Rapid IL-15-independent memory CD8+ T cell expansion following challenge of immune mice compensated for the limited memory CD8+ populations in IL-15-/- mice. However, despite expansion and expression of potent effector function, viral clearance was delayed in the absence of IL-15, coinciding with a rapid loss in cytolytic function.