As highlighted by the COVID-19 global pandemic, elderly individuals comprise the majority of cases of severe viral infection outcomes and death. A combined inability to control viral replication and exacerbated inflammatory immune activation in elderly patients causes irreparable immune-mediated tissue pathology in response to infection. Key to these responses are type I, II, and III interferons (IFNs), which are involved in inducing an antiviral response, as well as controlling and suppressing inflammation and immunopathology. IFNs support monocyte/macrophage-stimulated immune responses that clear infection and promote their immunosuppressive functions that prevent excess inflammation and immune-mediated pathology. The timing and magnitude of IFN responses to infection are critical towards their immunoregulatory functions and ability to prevent immunopathology. Aging is associated with multiple defects in the ability of macrophages and dendritic cells to produce IFNs in response to viral infection, leading to a dysregulation of inflammatory immune responses. Understanding the implications of aging on IFN-regulated inflammation will give critical insights on how to treat and prevent severe infection in vulnerable individuals. In this review, we describe the causes of impaired IFN production in aging, and the evidence to suggest that these impairments impact the regulation of the innate and adaptive immune response to infection, thereby causing disease pathology.

Zika virus (ZIKV) has emerged as a significant health threat worldwide. Although typically mosquito-borne, recent evidence suggests that ZIKV is also a sexually transmitted virus. While persistent ZIKV infections in male reproductive tissues have been identified, little is understood regarding the outcomes of primary sexual transmission in females. We investigated how the route of infection affects vaginal ZIKV shedding and dissemination. In two mouse models, vaginal infection resulted in prolonged ZIKV shedding in the vaginal mucosa with delayed systemic infection. Furthermore, heightened vaginal inflammation did not influence ZIKV replication or dissemination, in contrast to previous studies of mosquito-borne infection. Thus, vaginal infection significantly alters ZIKV infection kinetics and must be considered when developing novel treatments.

Herpes simplex virus type 2 (HSV-2) infection is one of the most prevalent sexually transmitted infections that disproportionately impacts women worldwide. Currently, there are no vaccines or curative treatments, resulting in life-long infection. The mucosal environment of the female reproductive tract (FRT) is home to a complex array of local immune defenses that must be carefully coordinated to protect against genital HSV-2 infection, while preventing excessive inflammation to prevent disease symptoms. Crucial to the defense against HSV-2 infection in the FRT are three classes of highly related and integrated cytokines, type I, II, and III interferons (IFN). These three classes of cytokines control HSV-2 infection and reduce tissue damage through a combination of directly inhibiting viral replication, as well as regulating the function of resident immune cells. In this review, we will examine how interferons are induced and their critical role in how they shape the local immune response to HSV-2 infection in the FRT.

Increasing interest is being focused on the role of protein kinase C (PKC) in the mode of action of interferons (IFNs). Here we report that IFN-alpha induced a transient translocation of PKC from the cytosol to the particulate fraction of U937 cells. In contrast, after IFN-gamma treatment, no significant change in PKC activity could be observed. IFN-induced changes in membrane potential were also examined by means of a potential sensitive oxonal dye and flow cytometry. Hyperpolarization was induced by both IFN-alpha and IFN-gamma. The protein kinase inhibitor H-7 blocked the hyperpolarization induced by IFN-alpha but not by IFN-gamma. These concordant results suggest that PKC is involved in the early signals of IFN-alpha but not of IFN-gamma in U937 cells.

Following the recent outbreak of Zika virus (ZIKV) infections in Latin America, ZIKV has emerged as a global health threat due to its ability to induce neurological disease in both adults and the developing fetus. ZIKV is largely mosquito-borne and is now endemic in many parts of Africa, Asia, and South America. However, several reports have demonstrated persistent ZIKV infection of the male reproductive tract and evidence of male-to-female sexual transmission of ZIKV. Sexual transmission may broaden the reach of ZIKV infections beyond its current geographical limits, presenting a significant threat worldwide. Several mouse models of ZIKV infection have been developed to investigate ZIKV pathogenesis and develop effective vaccines and therapeutics. However, the majority of these models focus on mosquito-borne infection, while few have considered the impact of sexual transmission on immunity and pathogenesis. This review will examine the advantages and disadvantages of current models of mosquito-borne and sexually transmitted ZIKV and provide recommendations for the effective use of ZIKV mouse models.