Protoparvovirus

23 species are recognized, many containing several named viruses, virus strains, genotypes or serotypes. When applied to viruses, the definition of species is a little unusual.Van Regenmortel MHV (2000) Introduction to the species concept in virus taxonomy. In: Van Regenmortel MHV, Fauquet CM, Bishop DHL, Carstens EB, Estes MK, Lemon SM, McGeogh DJ, Maniloff J, Mayo MA, Pringle CR, Wickner RB. (eds) Virus Taxonomy-Seventh Report of the International Committee on Taxonomy of Viruses. Elsevier Academic Press, London. It is simply an abstract taxonomic concept that clusters a selected range of genetic variants, helping to distinguish branches in a phylogenetic lineage, but it is not a physical entity like a virus that can infect an animal or be isolated.Van Regenmortel MHV (2003) Viruses are real, virus species are man-made taxonomic constructions. Arch. Virol. 148: 2481–2488. If the diversity level used to define a species is set very low, many will effectively contain a single virus, and the virus and species may even be given the same name, resulting in confusion between the two concepts in the literature, and marginalizing the phylogenetic role of the species taxon. To counter this problem, the diversity level now recognized for species in the Parvoviridae is relatively broad: species are defined as a cluster of similar viruses that encode a particular replication protein, typically called NS1, that is at least 85% identical to the protein encoded by other members of the species.

The genus contains the following species, listed by scientific name and followed by the exemplar virus of the species:{{cite web|title=Species List: Parvoviridae|url=https://ictv.global/report/chapter/parvoviridae/taxonomy/parvoviridae|publisher=International Committee on Taxonomy of Viruses|access-date=26 March 2025}}

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• Protoparvovirus carnivoran1, Canine parvovirus; the species also contains Feline parvovirus
• Protoparvovirus carnivoran2, Sea otter parvovirus
• Protoparvovirus carnivoran3, Canine bufavirus
• Protoparvovirus carnivoran4, Fox parvovirus
• Protoparvovirus carnivoran5, Newlavirus
• Protoparvovirus carnivoran6, ParvoviridaeDogfe372C6
• Protoparvovirus carnivoran7, ParvoviridaeDogfe373C1
• Protoparvovirus carnivoran8, ParvoviridaeDogfe342C1
• Protoparvovirus chiropteran1, Megabat bufavirus 1
• Protoparvovirus chiropteran2, Bat parvovirus BtPk-PV/Switzerland/2019
• Protoparvovirus eulipotyphla1, Mpulungu bufavirus
• Protoparvovirus incertum1, Tusavirus
• Protoparvovirus pinniped1, California sea lion parvovirus Hanchett
• Protoparvovirus primate1, Bufavirus 1a
• Protoparvovirus primate2, Wuharv parvovirus 1
• Protoparvovirus primate3, Cutavirus
• Protoparvovirus rodent1, Minute virus of mice
• Protoparvovirus rodent2, Rat parvovirus 1
• Protoparvovirus rodent3, Rat bufavirus SY-2015
• Protoparvovirus ungulate1, Porcine parvovirus
• Protoparvovirus ungulate2, Porcine bufavirus
• Protoparvovirus ungulate3, Equine protoparvovirus
• Protoparvovirus ungulate4, Porcine parvovirus 8

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Protoparvoviruses that infect humans were first discovered in 2012 in the feces of children from Burkina Faso, and named using the siglum bufavirus.Phan TG, Vo NP, Bonkoungou IJ, Kapoor A, Barro N, O’Ryan M, Kapusinszky B, Wang C, Delwart E. 2012. Acute diarrhea in West African children: diverse enteric viruses and a novel parvovirus genus. J Virol. 86:11024–30 Three genotypes of bufaviruses have so far been detected, circulating in Tunisia, FinlandVäisänen E, Kuisma I, Phan TG, Delwart E, Lappalainen M, Tarkka E, Hedman K, Söderlund-Venermo M. 2014. Bufavirus in feces of patients with gastroenteritis, Finland. Emerg Infect Dis. 20(6):1078–80. and BhutanYahiro T, Wangchuk S, Tshering K, Bandhari P, Zangmo S, Dorji T, Tshering K, Matsumoto T, Nishizono A, Söderlund-Venermo M, Ahmed K. 2014. Novel human bufavirus genotype 3 in children with severe diarrhea, Bhutan. Emerg Infect Dis. 20(6):1037–9.

A second virus in this genus that infects humans —cutavirus— was initially isolated from the feces of children with diarrhea.Phan TG, Dreno B, da Costa AC, Li L, Orlandi P, Deng X, Kapusinszky B, Siqueira J, Knol AC, Halary F, Dantal J, Alexander KA, Pesavento PA, Delwart E

A new protoparvovirus in human fecal samples and cutaneous T cell lymphomas (mycosis fungoides). Virology 496:299–305. doi: 10.1016/j.virol.2016.06.013

A third potential human protoparvovirus —tusavirus 1— has been reported in the feces of a single human, but whether or not it is able to infect humans or was simply ingested remains to be clarified.Phan TG, Sdiri-Loulizi K, Aouni M, Ambert-Balay K, Pothier P, Deng X, Delwart E (2014) New parvovirus in child with unexplained diarrhea, Tunisia. Emerg Infect Dis 20(11):1911–1913. doi: 10.3201/eid2011.140428

Viruses in genus Protoparvovirus have non-enveloped protein capsids around 18–26 nm in diameter, which show T=1 icosahedral symmetry. Genomes are single-stranded linear DNA between 4–6kb in length, with small (100–500b) imperfect palindromic sequences at each terminus that fold to form distinctive duplex hairpin telomeres.

The capsid is thought to be made up of 60 VP proteins ({{PDB|2CAS}}), both VP1 and VP2.

The Protoparvovirus genome has two ORFs. The non-structural ORF (NS) is the "first" on the 5' side, with the structural (VP) on the 3' end. The genome is expressed by extensive alternative splicing. This not only allows for VP to be expressed, but also produces multiple alternatively spliced versions of each ORF, typically called NS1, NS2(P,Y,L), VP1, and VP2. Some examples of annotated proteins from UniProt are:

• NS1 of the Minute virus of mice (MVM), {{UniProt|P03134}}
• NS2 of MVM, {{UniProt|P0DJZ2}}
• VP1 of canine parvovirus (CPV), {{UniProt|P17455}}
• VP2 of CPV, {{UniProt|P61826}}

Viral replication is nuclear. Entry into the host cell is achieved by attachment to host receptors, which mediates clathrin-mediated endocytosis. Replication follows the rolling-hairpin model. In some virus/host cell combinations, progeny virions can be trafficked through the cytoplasm in vesicles and released from the parental host cell prior to cell death, while the remaining virions are released following cell lysis.

Vertebrates from 6 orders are currently known to serve as natural hosts. Transmission routes are typically fecal-oral and/or respiratory.

Kilham rat virus, isolated in 1959,Kilham, L. and Olivier, L. J. 1959. A latent virus of rats isolated in tissue culture. Virology 7: 428–37 was the first member of this family of small, linear, single-stranded DNA viruses to be identified.

In following years a series of physically similar viruses, including H1, LuIII, minute virus of mice and tumor virus X, were extracted from cells or tissues in routine use in research laboratoriesTattersall, P. 2006. The evolution of parvovirus taxonomy. In: ‘‘The Parvoviruses’’. J. Kerr, S. F. Cotmore, M. E. Bloom, R. M. Linden, and C. R. Parrish (eds), Chap. 1, pp. 5–4. Hodder Arnold, London. and porcine parvovirus, PPV, one of the major causes of reproductive failure in swine, was isolated from infected pigs.Ren X, Tao Y, Cui J, Suo S, Cong Y, Tijssen P. 2013. Phylogeny and evolution of porcine parvovirus. Virus Research. 178:392–397. In 1971 these viruses were all recognized as part of a taxonomic genus called Parvovirus in the First Report of the newly created International Committee on Taxonomy of Viruses (ICTV){{Cite web | url=http://ictvonline.org/taxonomyReleases.asp | title=International Committee on Taxonomy of Viruses (ICTV)}}

The Second ICTV Report, published in 1976, established the family Parvoviridae, which at that time included three genera, one of which retained the name Parvovirus and contained all of the aforementioned viruses plus feline panleukopenia virus (now called feline parvovirus, abbreviated to FPV), which had been shown to cause epidemics of enteritis, panleukopenia and congenital cerebellar ataxia in domestic cats. In 1978 a virus from the same species as FPV emerged that was able to infect dogs (called canine parvovirus or CPV), which rapidly spread globally, causing pandemics of severe intestinal and coronary disease.Hoelzer K, Parrish CR. 2010. The emergence of parvoviruses of carnivores. Vet. Res. 41:39.

Genus Parvovirus continued to accrue new viruses until 2014, when its name was changed to Protoparvovirus.

{{Reflist|2}}

• [http://viralzone.expasy.org/all_by_species/199.html Viralzone: Protoparvovirus]
• [http://ictvonline.org/virusTaxonomy.asp ICTV]

{{Baltimore classification}}

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Category:Parvovirinae

Category:Parvoviruses

Category:Virus genera