Canine Parvovirus Antibody Test (IFA)
Canine Parvovirus is a highly contagious virus infecting mostly dogs. The virus is shed in the feces and is spread by direct contact. Puppies and non-vaccinated young dogs are most susceptible to infection. The virus is single stranded DNA, non-enveloped, and very hard to inactivate once it is in an animal facility or clinic. Our studies show that during outbreaks in the 1980s, veterinary clinics and hospitals were the main focus of infection spread. CPV occurs in two clinical forms; intestinal and cardiac. There is a breed predilection for susceptibility with Rottweiler's, Dobermans, and Pitt Bulls at the top of the list.
In the intestinal form the virus is ingested and replicates in the lymphoid tissue of the throat and then goes viremic. The virus then attacks rapidly dividing cells in the intestines damaging them and allowing gut bacteria to invade the bloodstream and cause sepsis which leads to systemic inflammatory response syndrome (SIRS). SIRS leads to a range of complications that are all bad. The cardiac form occurs in puppies less than 8-weeks of age, they die suddenly from pulmonary edema.
The best way to definitively diagnose CPV infection is to detect virus antigen in the feces of infected dogs by ELISA or hemagglutination tests. Vaccines can protect dogs fairly well from CPV infection but the vaccination timing needs to be precise. If a puppy has any level of maternal antibody against CPV, that antibody will inactivate the vaccine virus before it can be seen by the puppies active immune system. Vaccines with large amounts of virus antigen can overwhelm maternal antibody and produce good and long lasting immunity but those types of vaccines are more expensive to make and hard to find. The most common technique is to start vaccinating puppies at 5-6 weeks of age and continue to do so on a weekly basis until a good solid IgG titer is seen.
Our test for Canine Parvovirus Antibody is a indirect fluorescent antibody (IFA) procedure that is carried out on Teflon matted glass slides that contain fixed virus infected cells (CPV2A Black Isolate/CRFK cells). This method requires the use of diluted patient serum being placed on the slides for 30-minutes at which time the slides are washed and a fluorescent conjugated anti-dog globulin is placed on the slide. If any antibodies to CPV are present in the patient serum they will combine with the CPV antigen fixed to the slide surface. The fluorescent antibody conjugate will then be bound to the CPV antibodies and the resulting antibody-conjugate complex viewed with an ultraviolet microscope are seen as bright areas of fluorescence. The total number of infected cells on our slides does not exceed 40% which leaves the negative cells to enhance contrast. IFA titers of 1:25 and above correlate with hemagglutination inhabitation titers considered to be protective.