TABLE 1.

Genetic characteristics, transmission, and clinical signs of ssRNA viruses.

Name	Genus	Genome and virion structure	Mode of transmission	Protein receptor	Mode of entry	Clinical signs	References
Coronaviridae
HCoV-229E	Alphacoronavirus	(+)ssRNA Enveloped	Respiratory droplets and close contact	CD13	Cell plasma membrane fusion; Caveolae-mediated endocytosis	Mild self-limiting respiratory infection and pneumonia colds	Nomura et al., 2004; Goh et al., 2012; Fehr et al., 2016
HCoV-NL63	Alphacoronavirus	(+)ssRNA Enveloped	Close contact	ACE2	Cell plasma membrane fusion; Clathrin-mediated endocytosis	Mild self-limiting respiratory infection and pneumonia colds	Goh et al., 2012; Fehr et al., 2016; Milewska et al., 2018
HCoV-OC43	Betacoronavirus	(+)ssRNA Enveloped	Respiratory droplets	N-acetyl-9-O-acetylneuraminic	Cell plasma membrane fusion; Caveolae-mediated endocytosis	Mild self-limiting respiratory infection	Owczarek et al., 2018; Fehr et al., 2016
HCoV-HKU1	Betacoronavirus	(+)ssRNA Enveloped	Close contact	O-acetylated sialic acid	Cell plasma membrane fusion; Endocytotic pathway	Mild self-limiting respiratory infection	Goh et al., 2012; Fehr et al., 2016
SARS-CoV	Betacoronavirus	(+)ssRNA Enveloped	Direct contact with infected individuals	ACE2	Cell plasma membrane fusion; Clathrin-mediated endocytosis; Clathrin and caveolae indipendent uptake	Severe acute respiratory syndrome	Lu et al., 2008; Wang et al., 2008; Fehr et al., 2016; World Health Organization [WHO], 2020
MERS-CoV	Betacoronavirus	(+)ssRNA Enveloped	Primarly from infected dromedaries and camels to people; Between people after close unprotected contact	DPP4	Cell plasma membrane fusion; Clathrin mediated endocytosis	Severe acute respiratory disease	Fehr et al., 2016; Al-Qahtani et al., 2017; Liang et al., 2018; World Health Organization [WHO], 2020
SARS-CoV2	Betacoronavirus	(+)ssRNA Enveloped	Airborne; Respiratory droplets and close contact	ACE2	Cell plasma membrane fusion; Endocytosis mediated pathway	Severe acute respiratory disease	Wang et al., 2008; Fehr et al., 2016; World Health Organization [WHO], 2020
Flaviviridae
HCV	Hepacivirus	(+)ssRNA Enveloped	Bloodborne	CD81; LDLR; SR-B1; CLDN1; OCLN	Receptor-mediated endocytosis	Acute and chronic hepatopathy; Liver cancer	Andrus and East, 2010; Colpitts et al., 2020; World Health Organization [WHO], 2020
DENV	Flavivirus	(+)ssRNA Enveloped	Mosquito-borne	Unidentified universal cell-surface receptor	Clathrin-mediated endocytosis	Acute flu-like illness; Severe dengue	Martinez-Gutierrez et al., 2011
WNV	Flavivirus	(+)ssRNA Enveloped	Mosquito-borne	DC-SIGN; Mannose receptor	Clathrin-mediated endocytosis	Fatal neurological disease	Colpitts et al., 2012; Vancini et al., 2013; Fares-Gusmao et al., 2019
ZIKV	Flavivirus	(+) ssRNA Enveloped	Mosquito-borne	DC-SIGN; TIM-1; AXL	Clathrin-mediated endocytosis	Mild, often asymptomatic illness; Congenital malformations in infants when contracted during pregnancy	Laureti et al., 2018; Fares-Gusmao et al., 2019
Filoviridae
EBOV	Ebolavirus	(−)ssRNA Enveloped	Blood, secretions, bodily fluids of infected people; Contaminated surfaces and materials	TIM-1; NPC1	Macropinocytosis	Hemorrhagic fever	Salata et al., 2019; World Health Organization [WHO], 2020
Orthomyxoviridae
IAV	Alphainfluenzavirus	(−)ssRNA Enveloped	Respiratory droplets	N-acetylneuraminic acid (sialic acid)	Receptor mediated endocytosis	Acute respiratory infections of varying severity	Edinger et al., 2014; World Health Organization [WHO], 2020