Canine bocavirus

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Electron microscopic view of canine bocavirus[1]

Bocaviruses are a ubiquitous opportunistic Parvoviridae family of zoonotic[2] single-stranded DNA virus closely related to canine parvovirus and considered to occur worldwide.

Bocaviruses are small (18 - 26 nm), icosahedral and non enveloped viruses which contains a non-structural nuclear protein critical for DNA replication and host evasion[3].

Like most other parvoviruses, bocaviruses can evolve rapidly displaying frequent recombination and mutation rates that approach the high mutation rates observed in RNA viruses[4].

These viruses, which normally reside in the gastrointestinal or respiratory tracts of dogs, cats, cows and humans, are transmitted via the fecal-oral route and have been isolated in Asia and the USA and significant morbidity and mortality have been noted.

Bocaviruses are also a common source of contaminants in human vaccine cell cultures, where they are effectively removed by passages in MDCK cells[5].

Bocavirus infections can cause respiratory and gastrointestinal symptoms in young dogs, but are also often subclinical in adults[6]. While many bocaviruses were initially identified in feces or respiratory secretion they can also be found in blood.

Three species are pathogenic in dogs:

  • Minute virus of canines - associated with neonatal diseases and infertility[7]
  • Canine bocavirus (strain Con-161) - associated with respiratory disease
  • Canine bocavirus 3 - associated with hemorrhagic gastroenteritis and hepatitis

Bocaviruses are believed to replicate through the parvovirus rolling hairpin model, which generate replication intermediates of concatemers with head-to-head or tail-to-tail structure[8].

Minute virus (MVC) was isolated in 1967 in the feces of a clinical healthy dog, and later recognized as causing neonatal diseases and fertility disorders.

The second species of dog bocavirus (Canine bocavirus, CBoV) was identified in 2011 in the respiratory samples from diseased and healthy dogs[9]. One genotype of CBoV was associated with respiratory disease as it showed higher prevalence in diseased animals than healthy controls. Variants of this CBoV were also detected in fecal, nasal, urine and blood samples collected from dogs in Hong Kong[10].

Canine bocavirus 3 has been reported in a dog which died from acute hemorrhagic gastroenteritis, hepatitis, necrotizing vasculitis, granulomatous lymphadenitis and anuric renal failure[11].

Animal shelters are more predisposed to harboring this virus, presumably due to higher density housing and concurrent parvovirus infections, as a higher prevalence of viruses has been reported in sheltered animals compared with the healthy pet population[12].

Clinical symptoms vary from acute mortality affecting multiple pups in a litter, to sudden-onset pneumonia, diarrhea and death[13]. Adult dogs are usually asymptomatically infected and act as carriers, although abortions have been recorded[14].

Diagnosis requires DNA testing via PCR assays[15].

There is no specific treatment and therapy is primarily supportive, with intravenous fluid replacement and broad-spectrum antimicrobial therapy.

References

  1. Look for a diagnosis
  2. Pratelli A & Moschidou P (2012) Host range of Canine minute virus in cell culture. J Vet Diagn Invest 24(5):981-985
  3. Li Q et al (2013) Identification and Characterization of Complex Dual Nuclear Localization Signals in Human Bocavirus NP1. J Gen Virol Feb 6
  4. Shackelton LA & Holmes EC (2006) Phylogenetic evidence for the rapid evolution of human B19 erythrovirus. J Virol 80:3666–3669
  5. Roth B et al (2012) Isolation of influenza viruses in MDCK 33016PF cells and clearance of contaminating respiratory viruses. Vaccine 30(3):517-522
  6. Manteufel J & Truyen U (2008) Animal bocaviruses: a brief review. Intervirology 51:328–334
  7. Sukhu L et al (2013) Characterization of the nonstructural proteins of the bocavirus minute virus of canines. J Virol 87(2):1098-1104
  8. Schildgen O et al (2012) Genomic features of the human bocaviruses. Future Virol 7:31–39
  9. Kapoor A et al (2012) Characterization of novel canine bocaviruses and their association with respiratory disease. J Gen Virol 93:341–346
  10. Lau SK et al (2012) Identification and characterization of bocaviruses in cats and dogs reveals a novel feline bocavirus and a novel genetic group of canine bocavirus. J Gen Virol 93:1573–1582
  11. Li L et al (2013) A novel bocavirus in canine liver. Virol J 10:54
  12. Steneroden KK et al (2011) A needs-assessment and demographic survey of infection-control and disease awareness in western US animal shelters. Prev Vet Med 98:52–57
  13. Decaro N et al (2012) Molecular characterization of Canine minute virus associated with neonatal mortality in a litter of Jack Russell terrier dogs. J Vet Diagn Invest 24(4):755-758
  14. Carmichael LE et al (1991) Pathogenicity of minute virus of canines (MVC) for the canine fetus. Cornell Vet 81:151–171
  15. Manteufel J & Truyen U (2008) Animal bocaviruses: a brief review. Intervirology 51:328–334