Calicivirus Infection in Cats

Abstract

Feline calicivirus (FCV) is a common pathogen in domestic cats that is highly contagious, resistant to many disinfectants and demonstrates a high genetic variability. FCV infection can lead to serious or even fatal diseases. In this review, the European Advisory Board on Cat Diseases (ABCD), a scientifically independent board of experts in feline medicine from 11 European countries, presents the current knowledge of FCV infection and fills gaps with expert opinions. FCV infections are particularly problematic in multicat environments. FCV-infected cats often show painful erosions in the mouth and mild upper respiratory disease and, particularly in kittens, even fatal pneumonia. However, infection can be associated with chronic gingivostomatitis. Rarely, highly virulent FCV variants can induce severe systemic disease with epizootic spread and high mortality. FCV can best be detected by reverse-transcriptase PCR. However, a negative result does not rule out FCV infection and healthy cats can test positive. All cats should be vaccinated against FCV (core vaccine); however, vaccination protects cats from disease but not from infection. Considering the high variability of FCV, changing to different vaccine strain(s) may be of benefit if disease occurs in fully vaccinated cats. Infection-induced immunity is not life-long and does not protect against all strains; therefore, vaccination of cats that have recovered from caliciviral disease is recommended.

Keywords: FCV; diagnosis; feline; genetic variability; multicat environment; tenacity; treatment; vaccination; vaccine strains; virulent systemic.

Figure 7

Oedema of the head and limbs in cats with VS-FCV infection. ©University Animal Hospital Zurich, Regina Hofmann-Lehmann.

Figure 8

Crusted lesions and ulcers of cats with VS-FCV infection: facial, mucocutaneous (lower lip and commissure) and ears. ©University Animal Hospital Zurich, Regina Hofmann-Lehmann.

Figure 9

Severe necrosis (philtrum, palate, tongue, lip commissure) in a cat with VS-FCV infection. ©University Animal Hospital Zurich, Regina Hofmann-Lehmann.

Figure 10

Excoriations of paws in a cat with VS-FCV infection. ©Katrin Hartmann. LMU Munich.

Figure 11

Jaundice and oedema of the subcutaneous tissue at necropsy of a cat with VS-FCV infection (case 11, [102]). ©Institute of Veterinary Pathology, Vetsuisse Faculty Zurich.

Figure 1

At high magnification, the eponymic goblets (calices) are visible on the virion surface. © Marian C. Horzinek.

Figure 2

(A) Genomic organisation of FCV genomic RNA with open reading frames (ORF) 1 to 3, antigenic regions (A to F) of the VP1 capsid precursor protein, hypervariable and conserved regions of antigenic region E and scheme of the structural domains of the capsid protein VP1 (N-terminal arm [NTA], shell [S], and protruding domain P with subdomains P1 and P2). (B) Schematic representation of the viral structure of FCV. Linear non-neutralising epitopes were recognised in the capsid region F and in a conserved area of E5′HVR; moreover, linear epitopes to neutralising antibodies were recognised in E5′HVR [16,17,18] (indicated by red circles; see figure legend). VPg = virus protein, genome linked. NTR = non-translated region. NTPas = nucleoside-triphosphatase. LC = capsid leader. HVR = hypervariable region. Not drawn to scale. Combined and adapted from [17,19,20,21].

Figure 3

Calicivirus infection limping syndrome. ©Uwe Truyen.

Figure 4

Ulcerative lesions on the tongue of cats with FCV infection. Left, ©Marian C. Horzinek; right, ©Tadeusz Frymus.

Figure 5

Hypersalivation in a cat with FCV infection. Tongue ulceration can be very painful, leading to impaired food and water uptake and hypersalivation. ©Tadeusz Frymus.

Figure 6

Feline chronic gingivostomatitis. ©University Animal Hospital Zurich, Felicitas Boretti.