Genus: Sapelovirus


Genus: Sapelovirus

Distinguishing features

Sapeloviruses are most closely related to members of the Enterovirus genus, but possess leader polypeptides of unknown functions. The 2A polypeptide may be a cysteine protease, but it is distinct from that of the enteroviruses. The 2B and 3A proteins are also very different from the enteroviruses. In both sapelovirus species the IRES is type IV, whereas in all enterovirus species it is type I.

Virion

Morphology

No surface morphology is visible by EM.

Physicochemical and physical properties

Viruses are very stable, resistant to acid pH and elevated temperatures (60°C for 10 min). Buoyant density in CsCl is 1.32–1.34 g cm-3

Nucleic acid

Genome (Tseng and Tsai 2007, Krumbholz et al., 2002, Oberste et al., 2003): c. 7,491–8,226 nt (5′-UTR: up to 741 nt; ORF: 6,969–7,566 nt; 3′-UTR: 82-235 nt). The IRES of all three sapelovirus species is type IV. The location of the cre has not been identified.

Genome organization and replication

Genome layout:

VPg+5′-UTRIRES-IV-[L/1A-1B-1C-1D/2Apro-2B-2C/3A-3B-3C-3D]-3′-UTR-poly(A)

The deduced polyproteins of the sapaloviruses range from 2,322–2,521 aa. The leader polypeptide porcine sapelovirus (PSV) and simian sapelovirus (SSV) are at 84 aa and 88 aa, respectively. The 2A polypeptides of PSV and SSV are both suspected to be a protease. The precise L/VP0 cleavage for PSV or SSV is not clear. The sequences in this region are quite well conserved between both viruses but it would require unusual cleavages in PSV (qL/GqvhS) and SSV (qC/GqvqS) to generate a myristoylation signal. VP0 is cleaved to VP4 and VP2 as shown by N-terminal sequencing of the VP2 polypeptide for SSV.

Antigenicity

Sapelovirus A consists of a single type, PSV-1,Sapelovirus B of three genetically-defined simian sapelovirus types, SSV-1 to SSV-3.

Biology

Sapeloviruses have been isolated from pigs and monkeys. Sapelovirus-like-specific RNA has also been detected in bats (several species), various rodents, cats, cattle, dogs, pigeons, quails, and sea lions. 

Species demarcation criteria

Members of a species of the genus Sapelovirus:

  • are less than 30% divergent in polyprotein aa sequence,
  • are less than 36% divergent in P1 aa sequence,
  • are less than 30% divergent in 2C + 3CD aa sequence,
  • have a similar genome base composition which varies by no more than 1%,
  • have a common genome organization. 

The divergence (number of differences per site between sequences) between members of different Sapelovirus species ranges from 0.39–0.63 for P1 and 0.35–0.51 for 3CD.

Member species

SpeciesVirus name(s)Exemplar isolateExemplar accession numberExemplar RefSeq numberAvailable sequenceOther isolatesOther isolate accession numbersVirus abbreviationIsolate abbreviation
Sapelovirus Aporcine sapelovirusV13AF406813NC_003987Complete genomePSV
Sapelovirus Bsimian sapelovirus 1SV2-2383AY064708NC_004451Complete genomeSSV-1
Sapelovirus Bsimian sapelovirus 2VRDLEU789367SSV-2
Sapelovirus Bsimian sapelovirus 3WUHARV sapelovirus 1 (rhesus monkey/USA/2010)JX627573SSV-3

Virus names, the choice of exemplar isolates, and virus abbreviations, are not official ICTV designations.

Derivation of names

Sapelo-: from simian, avian and porcine entero-like viruses