Pathogenesis of canine parvovirus enteritis: sequential virus distribution and passive immunization studies

Area of Science:

• Veterinary Virology
• Canine Pathology

Background:

• Canine parvovirus (CPV) causes severe enteric disease in puppies.
• Understanding CPV's initial distribution and pathogenesis is crucial for developing effective treatments.

Purpose of the Study:

• To investigate the sequential distribution and pathogenesis of canine parvovirus following oral inoculation in beagle dogs.
• To determine the relationship between systemic lymphoid tissue infection, viremia, and intestinal epithelial infection.

Main Methods:

• Oral inoculation of nine-week-old seronegative beagle dogs with CPV.
• Necropsy of dogs at sequential time points (days 1-6 post-inoculation) for tissue collection.
• Virus isolation, immunofluorescence testing, and light microscopy to detect viral presence and cellular changes.
• Passive immunization of littermates with convalescent canine serum to assess protective effects.

Main Results:

• Virus was detected in tonsil, retropharyngeal, and mesenteric lymph nodes by days 1-2 post-inoculation.
• Systemic and intestinal lymphoid tissue infection, associated with viremia, occurred by day 3.
• Intestinal epithelial infection and fecal virus excretion began on day 4 post-inoculation.
• Intestinal lesions progressed from day 4 to day 6, correlating with lymphoid tissue lesions and viremia severity.
• Passively immunized dogs showed no clinical signs, lymphopenia, or fecal virus excretion, and lacked demonstrable intestinal epithelial infection.

Conclusions:

• Canine parvovirus initially targets lymphoid tissues, leading to viremia prior to intestinal epithelial invasion.
• The severity of intestinal disease is linked to the extent of systemic lymphoid involvement and viremia.
• Passive immunization with convalescent serum is effective in preventing CPV infection and disease in susceptible puppies.