Rappel

The main etiological agent of canine parvovirus is parvovirus type 2 (including subtypes CPV2, CPV2a, CPV2b and CPV2c). The strains currently circulating in the field are CPV2a, CPV2b and CPV2c (or CPV2-Glu 426). A particular strain of CPV2c of Asian origin is currently also circulating in Europe. CPV2, which was responsible for most cases of parvovirus 20 or 30 years ago, no longer seems to be circulating in the field.
The main etiological agent of feline panleukopenia is feline parvovirus (FPV), in some cases canine parvovirus type 2 (2a, 2b or 2c) is isolated from feces of cats with panleukopenia.

Etiological agents

	Parvovirose canine	Feline panleukopenia
Fluently	CPV2a CPV2b CPV2c	FPV
Exceptionally	FPV CPV2	CPV2a CPV2b CPV2c

Vaccination against parvovirus or panleukopenia is carried out with homologous live virus vaccines (CPV2 or CPV2b for canine parvovirus and FPV for panleukopenia).
In dogs, all vaccines (whether high viral titer or not) contain CPV2, with the exception of Zoetis' Versican® vaccine (which contains a strain of CPV2b).

Vaccines

Chien		Cat
All vaccines except Versican®	Versican® (Zoetis)
CPV2	CPV2b	FPV

Characteristics of typing testing

The test developed by Scanelis makes it possible to distinguish 5 viral types: FPV, CPV2, CPV2a, 2b and 2c. However, FPV cannot be distinguished from two viruses that are very close genetically, MEV (Mink Enteritis Virus) and BFPV (Blue Fox Parvovirus) but which are not isolated in cats.

It does not make it possible to distinguish wild and vaccine strains of FPV or wild and vaccine strains of CPV2 (knowing that wild strains of CPV2 no longer seem to be circulating in the field). Sequencing analyzes of the VP2 capsid protein gene are essential to be able to carry out this type of analysis.
The typing test highlights polymorphisms on 3 codons (305, 323 and 426) of the VP2 protein gene.

Interests and use of typing testing

The typing test can be used after an analysis confirming parvovirus or panleukopenia.

Learn more about diagnosing Feline parvovirus by real-time PCR

In this case it makes it possible to type the majority strain in 100% of cases (study on 57 cases of canine parvovirus and 28 cases of panleukopenia) and presents a 100% correlation with the reference technique (partial sequencing of VP2).
Typing alone does not allow a diagnosis to be made because its diagnostic specificity is insufficient (some asymptomatic animals carry wild strains).
When the viral load is average or low, typing provides an answer in more than 90% of cases. Cases for which interpretation is difficult correspond to mixtures of strains.

When to use typing?

• Check the circulation of a wild strain of parvovirus in a workforce and identify it (particularly in the context of recent vaccination).
• Check the feline (FPV) or canine (CPV2a, 2b or 2c) origin panleukopenia in populations where dogs and cats live together (e.g. shelters, etc.).
• Check results with average viral load after recent vaccination on an animal showing clinical signs.

How to interpret the typing results?

	Canine sampling	Feline sampling
FPV	Extremely rare case, feline virus parvovirus.	Wild or vaccine strain (the distinction can possibly be made by complete sequencing of VP2).
CPV2	It is most likely a vaccine strain (to be interpreted depending on the protocol and vaccines used). Complete sequencing of VP2 will eventually make it possible to verify this.	The canine origin of panleukopenia is confirmed. To be compared to the epidemiological situation. There is cross-protection with feline panleukopenia vaccines.
CPV2a or 2c	Wild strain of canine parvovirus (type 2c is the most recently isolated).
CPV2b	Wild strain or possibly vaccine strain (only if the animal has been recently vaccinated with Versican® from Zoetis).