FAQs DyNAgenics Verterinary Laboratory

B. Diagnoses of Specific Diseases

B1. What are the current PCR methods?
There are three (3) PCR Methods:

1) Single PCR Method:

Used for Toxoplasma, Ehrlichia, Bartonella, FeLV, Mycobacterium, Feline Herpes, Equine Herpes.
Difficulty interpreting results because PCR indicates organisms present but not causing disease. For example, Toxoplasma PCR on cats with uveitis: 19% PCR Positive compared with cats without uveitis 9% positive

2) Nested PCR Method:

3) Reverse Transcription PCR (RT-PCR) Method

B2. What specific diseases can be diagnosed with PCR testing?
FeLV (Feline Leukemia Virus)

Single PCR method.
Synbiotics research: 62 feline blood samples from Antech Labs were analyzed by ELISA, IFA and Synbiotics FeLV PCR. PCR had good correlation with strong positive IFA and strong positive ELISA. However, weak positive IFA conflicted with PCR.
45 samples strong positive ELISA/42 PCR Positive/93% correlation.
5 samples weak positive ELISA/2 PCR Positive/40% correlation
PCR is helpful in resolving conflicts between antibody based tests.

FIV (Feline Immunodeficiency Virus)

Double PCR Method.
Single PCR results with 12 antibody positive cats: 7 FIV PCR positive.
Double PCR on the same 12 cats: 12 PCR positive.
Note: Some cats fail to produce antibodies after infection, i.e., False Negative ELISA & Western Blots. False positive ELISA in kittens less than 6 months.
PCR is more sensitive for FIV detection--patent restrictions prohibit its commercial application.

FIP (Feline Infectious Peritonitis)

RT-PCR (Reverse Transcription Polymerase Chain Reaction).
RNA must be converted to DNA in two-step procedure.
Test detects small amounts of virus in effusions, plasma, and feces. Symbiotics
Study: 40 cases from Antech Laboratories analyzed by the Synbiotics PCR Assay. All 40 cases presented with effusive e fluid. Results: 18 cases PCR Negative: 14-not FIP, 3 FIP, 1 Uncertain.
22 Cases Positive FIP PCR: 20-FIP positive, 1-Negative, and 1-Uncertain. All confirmed FIP Positive cats Died (Necropsy, cytology, histology, clinical outcome). All FIP Negative Cats are alive.
Accuracy: 87% for sensitivity and 93% for specificity.
Considerations: Cats with dry FIP or a localized lesion may not have virus in the blood that may result in false negative results. FIP-PCR is specific and works well on effusions but lacks sensitivity when performed on whole blood. RNA is very fragile and may degrade if the sample is stored incorrectly or is too old. Keep it cold but not frozen in an EDTA (lavender top) tube.

Haemobartonella felis (FIA)

Single PCR. PCR more sensitive than cytology, e.g., cat with profound FIA-induced anemia was cytology positive and PCR positive.
Treated with antibiotics.
After treatment, cat became cytology negative and PCR positive for several weeks. (Symbiotics Data).
20 suspect FIA cats were PCR positive
10 known negative FIA cats PCR negative (Synbiotics data)

B3. Are there other single step PCR Tests are available?

B4. Are there other RT-PCR Tests available?

Canine Distemper (very sensitive as a research issue is whether Distemper PCR tests will detect vaccine virus in recently vaccinated dogs)