Canine Parvovirus

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Canine Parvovirus

• Introduction
• Family Characteristics Structure
• Parvovirus Types
• Pathogenesis
• Signs Symptoms
• Diagnosis
• Treatment
• Prevention Control
• Etiology/ Epidemiology
• Evolution
• Even More Pictures!
• Helpful Links
• References
• Created by Christie Anton, Jason Atkins,
  Rebecca Morgan Bryan Neves

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IntroductionFamily Parvoviridae
Genus Densovirus
Genus Parvovirus
Source for pictures http//viperdb.scripps.edu/g
allery_maker.php
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General Characteristics of Family
ParvoviridaeMorphology

• Virion is non-enveloped
• Nucleocapsids are 18-26 nm in diameter
• Symmetry is icosahedral with capsids (protein
  coat surrounding DNA) made up of 60 molecules of
  overlapping capsid proteins designated VP1,
  VP2, VP3
• Surface projections appear as small, rough spikes
• Source for pictures
• http//www.virology.net/Big_Virology/BVDNAparvo.ht
  ml
• Diagram source
• http//web.uct.ac.za/depts/mmi/stannard/linda.html

X-ray crystallography of canine parvovirus
Icosahedron
EM of canine parvovirus
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General Characteristics of Family
ParvoviridaeGenome

• DNA is single-stranded ( sense or a combination
  of both and -), linear, and 5Kb
  long.
• Palindromic sequences (100-300 nucleotides long)
  form a hairpin structure, which is important for
  initiation of replication.

• Palindromic sequences resulting in
• hairpin structure.
• Diagram source http//servet.uab.es/
  avillaverde/Caan/data/figs/3-9.htm

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Parvovirus Types

• The genus Parvovirus contains viruses that are
  some of the smallest and hardiest of bugs, able
  to survive in a wide range of climatic conditions
  in nature.
• These viruses also have a variable host range,
  infecting many different mammal bird species in
  which the viruses have been named accordingly
  Canine Parvovirus (CPV), Feline Parvovirus (FPV),
  Porcine Parvovirus (PPV), Bovine Parvovirus
  (BPV), Goose Parvovirus (GPV), etc., etc.
• CPV in particular is an example of an emerging
  virus due to its recent appearance (1970s) and
  rapid spread throughout the world.
• The evolutionary capabilities of this virus has
  produced many types to date, and is related to
  the ever-changing virulence of this bug.
• Specific Types
• CPV-1 a.k.a. canine minute virus (CMV). This is
  the first described canine parvovirus in late
  60s / early 70s that is associated with fetal
  viral infections, that leads to reproductive
  failure and neonatal respiratory disease. It
  may also produce enteritis in puppies and older
  dogs. However, it has been shown by DNA
  sequencing to be more closely related to bovine
  parvovirus (BPV) than canine parvovirus today
  that is descended from feline parvovirus (FPV).
  Schwartz et al.
• CPV-2 This emerged suddenly in 1978, most
  likely from FPV, to cause gastroenteritis in
  adult dogs and myocarditis in very young pups.
  After jumping the species barrier from FPV,
  CPV-2 was further selected for growth within dog
  cells, making dogs a better and natural host
  Strauss p 276.
• CPV-2 mutated and evolved again in 1979 to give
  us CPV-2a , in 1984 to produce CPV-2b, and
  finally CPV-2c most recently in Italy, Vietnam,
  and Spain Decaro et al..

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Canine Parvovirus Pathogenesis(CPV-2)

• Incubation 3-8 days, with shedding of the virus
  beginning on the 3rd day, before the appearance
  of clinical signs.
• Transmission is either through direct contact
  with infected dogs feces, or indirectly through
  fecal-contaminated fomites. The virus may be
  shed up to 3 weeks following infection and may
  survive up to 9 months in a contaminated area.
• Following inhalation or ingestion, the virus will
  initially replicate within the lymphoid tissues
  of the oropharynx region.
• Now in the bloodstream, the virus will seek out
  rapidly dividing cells such as bone marrow
  cells, lymphopoietic cells, and intestinal
  epithelium, leading to viremia and further
  replication and lysis of these host cells.
• Tropism for intestinal epithelium leads to
  collapse of intestinal villi, epithelial
  necrosis, and hemorrhagic diarrheaclinical signs
  of gastroenteritis.
• Depletion of lymphocytes and compromised
  gastrointestinal system may lead to bacteremia by
  normal gut flora, i.e. Escherichia coli, which
  can be fatal.

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Canine Parvovirus Pathogenesis
Dilated crypt epithelium
Acute hemorrhagic enteritis
Source for drawings http//www.veterinarypartner.
com/Content.plx?PAC189A581SourceID
Source for pictures http//w3.vet.cornell.edu/nst
/nst.asp?FunHome
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Signs Symptoms

• Signs and symptoms are related to usually 2
  disease presentations gastroenteritis and
  myocarditis. Myocarditis however is rarely an
  issue currently due to immunization practices in
  the mothers Merck.
• Initial signs of CPV infection depression,
  fever, anorexia, vomiting, and severe diarrhea.
  Feces may be yellowish gray due to the presence
  of mucus. The feces may also contain blood due to
  the onset of hemorrhagic enteritis.
• Dehydration is also common due to the rapid loss
  of fluids from vomiting and loose stools. Some
  very unfortunate puppies may experience
  projectile, bloody diarrhea and vomit until their
  deaths (48-72 hrs following obvious signs).
• CPV infections have been misdiagnosed,
  unfortunately due to the similarities in symptoms
  to parasitic infections, stress colitis, or
  perhaps the dogs last meal was disagreeable!
• So, the correct diagnostic tools are crucial to
  prevent the deaths of such young pups!

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Diagnosis
Testing is the only way that you will know for
certain if you have a parvovirus problem.
The following are some common practices performed
in veterinary offices or laboratories

• Extensive history based upon clinical signs
• Positive fecal ELISA result to confirm
• Newest diagnostic tools
• ELISA (Enzyme-Linked Immunosorbent Assay)
• The ELISA test is the most efficient test to use.
  It takes only 15 minutes and can be easily
  performed in the veterinary office.
• However, ELISA is a very sensitive test and can
  be influenced by some different factors such as
  recent vaccination and onset of clinical signs,
  giving false positive or false negative results.

Diagram source
http//www.clinical-virology.org/pages/cvn/sp_gp/c
vn_gp_how.html
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Diagnosis

• Newest Diagnostic Tools
• PCR

Parvovirus PCR testing has been shown to be
a very effective and sensitive way to detect
canine parvovirus. Dogs that have been
experimentally exposed to parvo had positive
fecal PCR results from day three to day fourteen
after exposure. This gives you a much bigger
window of opportunity to diagnose the virus. The
PCR test will also find the presence of fecal
parvo DNA even when an antigen test (ELISA)
showed a negative result.
Real-time PCR is the newest technology using
a minor groove binder (MGB) probe assay to
specifically identify CPV-2 vaccine strains and
field strain types (2a, 2b, and 2c). It is based
on the TaqMan technology, and this real-time PCR
has been proven to be even more specific,
sensitive, and reproducible than other
conventional methods such as hemagglutination
assays, immunochromatographic tests, viral
isolation, and even gel-based PCR Decaro, N. et
al..
Other advantages compared to conventional
PCR less time-consuming, less chance of
carry-over contamination. However, the molecular
assays, especially the real-time PCR method,
require expensive equipment, reagents and
specialized operators thus, their use as tests
for the veterinary practice is not feasible.
Nevertheless, there are efforts by several
companies to adapt molecular methods to clinical
practice, taking advantage of microchip
technology that would reduce the cost and size
of the equipment necessary for on site testing.
Costantina, D. et al..
EM Electron microscopy is another vital
diagnostic tool utilized to view the
morphological characteristics of extremely small
organisms, like parvoviruses, when standard
microscopy will not suffice. Even with all the
newest forms of diagnostic methods, EM is still
extensively used as a reference technique,
especially in cases of specimens expected to
contain high concentrations of the virus in
diarrheic stool samples. The WSVL currently uses
EM for diagnosis of parvovirus but it is also
developing a PCR test for typing of the virus.
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Treatment

• Supportive care
• replace lost fluids monitor electrolyte levels
• Control vomiting
• withhold food and water
• if persistent, the compound metoclopramide can be
  administered Merck.
• once vomiting has subsided, a bland diet such as
  cottage cheese and rice will suffice
• Gradually reintroduce regular diet
• Antibiotic therapy
• in the most severe cases, such as bacteriemia and
  septicemia, antibiotics should be administered
  with a broad spectrum series Merck.

Note Prevention and control of the virus is the
most effective means of treatment.
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Prevention Control

• Vaccination
• Decontamination
• Isolation
• Vaccination
• The most important form of prevention is to
  vaccinate against CPV-2a and CPV-2b. The most
  effective vaccination available is the
  live-attenuated canine parvo. It is most
  important to vaccinate puppies, however adult
  dogs that have been continuously vaccinated are
  at low risk and may not need to be vaccinated so
  often. To protect puppies from infection, a
  series of vaccine shots should be given every 2-4
  weeks until they are 16 weeks old. By that time
  the maternal antibodies will have gone and the
  vaccine will be able to take affect Mar Vista
  Animal Medical Center.
• Decontamination
• The only absolutely effective disinfectant is
  bleach at a 130 dilution. Use to disinfect
  hands, clothing, food and water bowls, toys,
  anything that the puppy may come into contact
  with, or has regular contact with Merck.
• Isolation
• Infected animals must be isolated from healthy
  animals to prevent the spread of the virus.
  Places of high risk are dog shows, field trials,
  boarding kennels and public spaces reserved for
  dogs.

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Etiology/ Epidemiology
Canine parvovirus disease is currently the most
common infectious disorder of dogs in the United
States.

• Canine parvovirus is an extremely hardy bug that
  is able to withstand harsh environmental
  conditions and common disinfectants.
• Highly contagious
• Mainly affects young puppies that are 6-20 wks
  old due to a limbo period of decreased antibody
  protection from the mother and the inadequate
  vaccination protection for the young pups
  Merck.
• Adult dogs may be asymptomatic carriers and shed
  the virus periodically.
• Certain breeds seem to be particularly
  susceptible Rottweilers, German Shepherds,
  Doberman Pinschers, and American Pit Bull
  Terriers Merck.
• Mortality rate is variable 16-48 Merck.

Pet education.com
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Evolution

• The evolution of Canine Parvovirus is perhaps one
  of the most important, and closely studied,
  evolutionary pathway in diagnostic virology. This
  evolutionary map shows in detail how the current
  strains of Canine Parvovirus (CPV-2a and CPV-2b)
  came into being.
• Diagram source Uwe Truyen (Veterinary
  Microbiology)

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Evolution

• Prior to the emergence of Canine Parvovirus, this
  virus infected the cat (Feline panleukopenia
  virus or FPLV) and mink (Mink enteritis virus or
  MEV).
• A mutation of just 2 amino acids enabled FPLV to
  evolve and make a leap between species.
• At least 11 conserved nucleotide differences (7
  nonsynonymous and 4 synonymous changes) were seen
  between CPV-2 isolates and FPLV-type viruses in
  the capsid VP2 sequence. However, CPV and FPLV
  isolates differ in lt2 of their genomic DNA
  sequences.
• In 1978, CPV-2 appeared, quickly spreading
  worldwide within a couple of months, infecting
  and killing thousands of dogs. This strain of
  parvovirus could not replicate well in cats.
• Discovered some years later in 1983, a virus
  isolated from Artic Fox from Finland (Blue Fox
  Parvovirus or BFPV ), while being essentially the
  same as MEV-2, had three synonymous nucleotide
  changes in the VP2 gene that were specific for
  the canine sequence. This suggests that BFPV may
  have been an evolutionary intermediate between
  FPLV and MEV, and CPV-2.

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Evolution

• With the introduction of vaccines, dogs started
  to develop immunity to CPV-2. This forced the
  virus to mutate once again.
• The new antigenic type, CPV-2a, became the more
  commonly seen strain by 1981. CPV-2 was rarely
  seen after this point in time. This marked the
  death of the original Canine parvovirus strain.
• The new strain of CPV-2a differed from CPV-2 in
  that it had lost at least one epitope recognized
  by monoclonal antibodies (MAbs) and gained a new
  specific epitope.
• In 1984, yet another new antigenic type, CPV-2b
  appeared. This strain overtook CPV-2a as the
  parvovirus dogs are most commonly infected with
  in the United States.
• Both these antigenic types, CPV-2a and CPV-2b
  replicate effectively in cats. In fact, domestic
  cats and wild felines both present with these
  viruses today.
• The newest antigenic type is CPV-2c. This strain,
  discovered in 1997, has only been found in
  Leopard cats. The virulence of CPV-2c in dogs has
  yet to be determined.

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Helpful Links

• http//www.workingdogs.com/parvofaq.htm
• http//www.avma.org/careforanimals/animatedjourney
  s/pethealth/canine.asp4
• http//www.avma.org/communications/brochures/canin
  e_parvo/parvo_brochure.asp
• http//www.veterinarypartner.com/Content.plx?PAC
  A1199SourceID
• http//www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB
• http//www.marvistavet.com/html/canine_parvovirus.
  html
• http//www.cpvh.com/Articles/39.html
• http//www.peteducation.com/article.cfm?cls2cat
  1554articleid4
• http//www.cdc.gov/
• http//viperdb.scripps.edu/links.php

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References

• Costantina, D. et al. Canine Parvovirus
  Infection Which Diagnostic Test for Virus?
  Journal of Virological Methods 126 (2005)
  179-185.
• Decaro, N et al. Occurrence of Severe
  Gastroenteritis in Pups After Canine Parvovirus
  Vaccine Administration A Clinical and
  Laboratory Diagnostic Dilemma. Vaccine (2006),
  doi10.1016/j.vaccine.2006.10.020
• Ikeda, Y. et al. Feline Host Range of Canine
  Parvovirus Recent Emergence of New Antigenic
  Types in Cats. Immerging Infectious Diseases,
  Vol. 8, No.4 (2002) pp 341-346.
• Kahn, Cynthia M. ed. The Merck Veterinary Manual
  9th edition. Whitehouse Station Merck Co,
  2005.
• Parrish, C.R, et. al. Rapid Antigenic-Type
  Replacement and DNA Sequence Evolution of Canine
  Parvovirus. Journal of Virology, Vol. 65, No.
  12 (1991) pp. 6544-6552.
• Schwartz, D., B. Green, L.E. Carmichael and C.R.
  Parrish. The Canine Minute Virus (minute virus
  of canines) is a Distinct Parvovirus That is Most
  Similar to Bovine Parvovirus. Virology 302
  (2002), pp. 219223.
• Strauss, James H., and Ellen G. Strauss. Viruses
  and Human Disease. San Diego Academic Press,
  2002.
• Truyan, Uwe. Evolution of Canine Parvovirus-A
  Need for New Vaccines. Veterinary Microbiology
  117 (2006) 9-13.
• Web references
• Canine Parvovirus. Mar Vista vet.com. 2000.
  Mar Vista Animal Medical Center. 11 Dec. 2006
• http//www.marvistavet.com/html/body_vaccination_
  options_prevention.html.
• Parvovirus. Pet Education.com. 2006. Drs.
  Foster Smith, Inc. 11 Dec. 2006
• http//www.peteducation.com/article.cfm?cls2cat
  1554articleid4.