Human Acute and Chronic Viruses: Host-Pathogen Interactions and Therapeutics

Viruses are obligate intracellular pathogens that cause infection in susceptible host cells. Virus infections could be lytic, chronic, latent or immortalizing. Viruses causing latent infection are associated with high morbidity and mortality worldwide. The human body is protected from viral infection by physical and chemical barriers. However, when these barriers are breached, the body generates an antiviral immune response mediated by Natural killer (NK) cells, monocytes, Dendritic Cells (DCs), type I interferon (IFN), neutralizing antibodies, and T cells. DCs play an important role in generating a cell-mediated adaptive immune response to viruses, with conventional DCs playing a crucial role in the interactions between DCs and viruses. Crosstalk between NK cells and DCs facilitates DC maturation in antiviral innate immunity whereas crosstalk between DCs and T cells in antiviral adaptive immunity amplifies the function of mature DC. Viruses employ various strategies to evade the host immune system. They can block Pattern Recognition Receptors (PRRs) - mediated production of type I IFNs, inhibit maturation and functionality of DCs, and interfere with cell-mediated immunity. Here we will focus on important human disease-causing viruses including latest COVID19 that caused worldwide pandemic. Because of the high mortality rate associated with viral diseases, there is an urgent need to re-evaluate current antiviral agents with more research focusing on developing alternative anti-viral therapies with an enhanced therapeutic index and safety profiles. Future directions in approaching the development of vaccines should focus on specific vaccines that can induce CD8+T cell responses and produce IFN-gamma to promote a Th1-biased CD4+T-cell response.