Qmini Real-Time PCR: Bringing Real-Time PCR Testing to your Clinics

Follow our Pages for the latest updates

Differences between PCR, Antigen, and Antibody Tests for Infectious Disease

Veterinarians use a variety of veterinary tools to detect the presence of organisms that can cause disease, and to assess the overall health of an animal. To achieve this purpose, rapid tests or PCR tests have become necessary almost worldwide in animal clinics. These tests help veterinarians determine if the animal is infected with the specific infectious disease. When should veterinarians use an antigen test, PCR test, or an antibody test? Below, we will provide an overview on all three types of tests and the difference between them.

Rapid antigen tests are immunoassays that require certain specimen types, depending on the detected pathogens, from the patient. Once collected, samples are placed in an extraction buffer or reagent and tested for the presence of pathogen’s specific antigens. Antibody (or serology) tests use the blood sample to look for antibodies that your immune system produced in response to the infection of a pathogen or vaccination. Both tests can provide results within 15 minutes. They are generally considered to be less accurate than PCR tests, but they are much easier to administer and more cost-effective.

A PCR test is a molecular test. The PCR technique can generate millions of copies from a very small amount of DNA/RNA. PCR testing also requires certain specimen types, depending on the detected pathogens, from the patient. Samples are then processed and tested for DNA/RNA of specific pathogen. The test includes extraction of DNA/RNA from the patient specimen, conversion to DNA (for detecting RNA viruses) and PCR amplification with pathogen-specific primers. The PCR test isn’t quite as convenient and cost-effective as a rapid test, but it’s extremely accurate.

Differences between PCR, rapid antigen / antibody tests are summarized in the table below.

Bioguard’s Qmini Real-Time PCR Analyzer for the Detection of Feline Respiratory Tract Disease Complex

Feline respiratory disease (FRD) syndrome or feline upper respiratory tract disease complex is a common infection in cats caused mainly by Feline Herpesvirus (FHV-1), Feline Calicivirus (FCV), Chlamydophila felis, Mycoplasma spp, and Bordetella bronchiseptica. About 90% of all upper respiratory infections are caused by FHV-1 and FCV.

Common Symptoms:
• Sneezing
• Nasal congestion
• Conjunctivitis (inflammation of the membranes lining the eyelids)
• Discharge from the nose or eyes (clear, purulent, or cloudy containing pus).
• Difficulty breathing
• Ulcers in the mouth

Less specific symptom
• Less appetite
• lethargy
• fever
• enlarged lymph nodes
• blepharospasm (squinting)

Sources of infection:
• Susceptible cats can get an infection by contagious particles in saliva or secretions from the
  nose or eyes shredded by an infected cat.
• Most cases are associated with direct contact
• Natural transmissions can also occur via aerosol droplets.
• Stress may also cause a secondary course of illness.

Real-Time PCR for Diagnosis:
A definitive diagnosis is based on clinical signs and laboratory testing for the isolation and identification of the infection. The Polymerase chain reaction (PCR) test is one of the sensitive tests and most reliable for detecting the presence of infectious agents. PCR detects the genomic material of the pathogen and determines its presence in the host. It is often more sensitive and specific than other available tests. However, false negative results are still expected.

In the case of patients with latent herpes infections where the FHV-1 is found in the trigeminal ganglion can give negative PCR results. In the case of Chlamydophila, 2-3 days of antibiotic treatment for patients can also have negative PCR results.

Samples of ocular, nasal, or caudal pharyngeal secretions for PCR assay are best for the diagnosis and identification of causative agents.

Sample collection tips:
• Ocular: Moisten with tears/exudate well or firmly swab both of the conjunctival sacs with a
  clean, dry swab.
• Clinical lesions: Prefer to swab from the nasal and pharyngeal areas. Tissue fragments or
  biopsies can also be done.
• After sample collection, place the swab in a sterile container at 4°C until nucleic acid
  extraction.

Real-Time PCR for Diagnosis:
A definitive diagnosis is based on clinical signs and laboratory testing for the isolation and identification of the infection. The Polymerase chain reaction (PCR) test is one of the sensitive tests and most reliable for detecting the presence of infectious agents. PCR detects the genomic material of the pathogen and determines its presence in the host. It is often more sensitive and specific than other available tests. However, false negative results are still expected.

In the case of patients with latent herpes infections where the FHV-1 is found in the trigeminal ganglion can give negative PCR results. In the case of Chlamydophila, 2-3 days of antibiotic treatment for patients can also have negative PCR results.

Samples of ocular, nasal, or caudal pharyngeal secretions for PCR assay are best for the diagnosis and identification of causative agents.

Sample collection tips:
• Ocular: Moisten with tears/exudate well or firmly swab both of the conjunctival sacs with a
  clean, dry swab.
• Clinical lesions: Prefer to swab from the nasal and pharyngeal areas.

After sample collection, place the swab in a sterile container containing preservation buffer at 4°C until nucleic acid extraction.

About Bioguard Corporation

The Bioguard is a company focusing on animal disease diagnostic services and products.
Our animal health diagnostic center is the first and only ISO/ IEC 17025 accredited animal disease testing laboratory in Taiwan and China.

Our mailing address is: [email protected]