In an attempt to investigate the effects of ginsenosides on rhinovirus infection, Song et al  examined the antiviral activities of protopanaxatriol (PT)-type ginsenosides (Re, Rf, and Rg2), and protopanaxadiol (PD)-type ginsenosides (Rb1, Rb2, Rc, and Rd). The results showed that PT-type ginsenosides protected He La cells from human rhinovirus 3 (HRV3)-induced cell death as determined by sulforhodamine B staining of viable cells and morphological assessment .
Future studies are needed to elucidate the relationship between the antiviral activities and structural differences among panaxadiol- and panaxatriol-type ginsenosides.
Influenza virus is the most common human respiratory pathogen that causes annual endemic and periodic pandemic infection.
In addition to anticancer, anti-inflammatory, and immune-modulatory activities, KRG and its purified components have also been shown to possess protective effects against microbial infections.
Here, we summarize the current knowledge on the properties of KRG and its components on infections with human pathogenic viruses such as respiratory syncytial virus, rhinovirus, influenza virus, human immunodeficiency virus, human herpes virus, hepatitis virus, norovirus, rotavirus, enterovirus, and coxsackievirus.
In addition, the continuous emergence of new infectious agents such as the Ebola virus and Middle East respiratory syndrome coronavirus (MERS-Co V) necessitate the advancement of novel therapeutic approaches.
Accordingly, great attention has recently been drawn to the development of antivirals with broad-spectrum efficacy and immunomodulators which improve host resilience by increasing host resistance to the viral infection . The data indicate that RGE possesses an immunomodulatory effect by balancing Th1 and Th2 immune responses, and protects the host from severe pulmonary inflammation upon FI-RSV immunization and RSV infection. In addition, RGE protected human epithelial cells from RSV-induced cell death and viral replication and inhibited the production of proinflammatory cytokines upon RSV infection , . Although extremely small in size and simple in structure, viruses cause numerous diseases such as cancer, autoimmune disease, and immunodeficiency as well as organ-specific infectious diseases including the common cold, influenza, diarrhea, hepatitis, etc. Recent progress in the formulation of antiviral therapies and vaccines has helped to prevent, shorten the duration, or decrease the severity of viral infection , , . Most antiviral agents are designed to target viral components, but mutations in the viral genome often result in drug resistance and immune evasion, creating a major hurdle for antiviral therapies and vaccine development . The Kang Laboratory (Georgia State University, GA) has published several studies on the immunomodulatory and antiviral effects of KRG extract (RGE) on RSV , , .