Dual role of glycans and binding receptors in pathogenesis of enveloped viruses (by mainly focusing on two recent pandemics).

A period of about a decade has been estimated to pass for the emergence of a new infectious strain of a virus that may lead to the occurrence of a pandemic one. It is now suggested that the variants of the 1918 H1N1 and coronavirus disease-19 pandemics could have existed in humans after the initial cross-species introduction to humans and underwent multiple low-level seasonal epidemics before the occurrence of their outbreaks. They share similarities in the continuation, widespreadness due to high transmissibility, high fatality rate and clinical symptoms. They are assumed to share a similar principle of a zoonotic source and a cross-species pathway for transmission. They show some similarities in their pathogenesis with other enveloped viruses: Severe Acute Respiratory Syndrome Coronavirus-1 (SARS-CoV-1), Middle East respiratory syndrome coronavirus (MERS-CoV), human immunodeficiency virus, Ebola, Lassa and measles viruses. The highly pathogenic nature of these viruses and their genetic variants may depend on their binding affinity for host cell receptors, whereby they efficiently circumvent or block host cell immune responses triggered by cytokines (interferon). High transmission rates and viral pathogenicity are attributed to glycan moieties that facilitate virus binding to host multiple receptors and cell entry, thereby helping viruses to evade immune recognition and response. Also, mucosa glycotopes are a matter of concern that play as primary sites for virus attachment and body entry. Finding general lectins or ligands that block the viral-host receptors interaction or identifying individual glycotopes is the therapeutic and prognosis topic that demands the main focus.