Molecular diagnostics

The Molecular Diagnostics section of the Animal Health Centre offers diagnostic testing for a wide range of animal pathogens using molecular biology based methods such as conventional and real-time PCR tests and DNA sequencing. 

Diagnostic and proficiency testing

This section develops and validates Polymerase Chain Reaction (PCR) methods for detection and typing of pathogens important to domestic poultry, wild and exotic birds, food and fur bearing animals, companion animals, wild and zoological species, marine mammals and aquaculture salmonids.  

In addition to routine diagnostic testing, the Molecular Diagnostics section undergoes proficiency testing conducted by the National Centre for Foreign Animal Diseases and USDA’s National Veterinary Services Laboratory.

Molecular diagnostics - submission requirements

Proper collection and handling of diagnostic specimens are critical for the success of virus detection and virus isolation techniques. As peak virus titers are usually present at the onset of clinical signs, diagnostic specimens for virus detection and virus isolation should be collected immediately after the animal first develops clinical signs. Collection of samples during the acute phase of viral infection usually provides sufficient amount of virus for detection by various assays. Samples collected later in the course of infection may lead to false negative results or misdiagnosis when secondary bacterial infection is involved.

The Animal Health Centre currently, uses Polymerase Chain Reaction (PCR) assays, virus isolation, Electron Microscopy (EM), Fluorescent Antibody Test (FAT) for direct detection of viruses in clinical samples. Many of the samples used for PCR can also be used for virus isolation if collected and stored properly.

Collection and storage

Samples must be aseptically collected and kept refrigerated immediately after collection. Samples that cannot immediately be transported to the laboratory should be stored at 4°C for a maximum of two days. Samples must be kept frozen at –70°C or lower for long term storage. The use of ice pack refrigerants to keep the specimens cold while in transit is extremely important for virus detection. If specimens are frozen, they must remain frozen in transit and not be allowed to thaw out.

Swabs for virology testing (PCR, Virus isolation and EM): Viral swabs can be submitted in virus transport medium (VTM) or Universal Transport Medium (UTM) or Brain Heart Infusion broth (BHI).

  • Use only dry polyester or dacron swabs on plastic handles for collection and submission of swab samples for virus isolation and PCR tests.
  • After thoroughly swabbing the area of interest, place the swab in the collection tube containing 3-5 ml of VTM or UTM or BHI and swirl vigorously.
  • Squeeze the liquid off the swab (press and roll) along the inside wall of the tube and discard swab into a disinfectant solution.
  • Securely close the cap and clean the outside of each tube and seal the tubes in plastic zip lock bags.
  • Store swabs at 4°C and transport immediately to the laboratory.

DO NOT USE:  Cotton-tipped or calcium alginate swabs, swabs with wood or paper handles or swabs in bacterial transport media and agar may not be used. Residual bleach and other chemicals in cotton swabs and wooden handles and agar in the bacterial transport media can be inhibitory to PCR and may inactivate viruses.

Swabs for bacterial PCR tests: Swabs can be submitted in sterile saline. Swabs submitted in bacterial transport media are not suitable for PCR testing.

Fresh tissues: Whenever possible, submit fresh tissues in a sterile, leak proof container for virus isolation and PCR assays. Autolyzed tissues are not suitable for virus isolation.

Whole blood: Use tubes containing anti-coagulants such as citrate (blue stopper), EDTA (purple stopper) or heparin (green stopper) and submit a minimum of 5 mL.

Feces: Submit approximately 10gm (10 – 20ml volume) in securely closed sterile container. Outer surfaces of the container must be clean and dry. Do not submit feces in plastic bags or gloves.