Evaluation of different sampling methods and results of real-time PCR for detection of feline herpes virus-1, Chlamydophila felis and Mycoplasma felis in cats

Epidemiological Investigation of Feline Upper Respiratory Tract Infection Encourages a Geographically Specific FCV Vaccine

A total of 1158 cats with feline upper respiratory tract infection were incorporated from twenty animal hospitals in Wuhan, China, from April 2019 to April 2022 to investigate the epidemiology of feline calicivirus (FCV), herpesvirus-1 (FHV-1), Mycoplasma felis (M. felis) and Chlamydia felis (C. felis) for the development of a geographically-specific FCV vaccine with reference to prevalence and risk factors for infection. The 871 samples (75.2%) of kittens were younger than 12 months, of which 693 were males, and 456 were females. Among the samples, 443 were British shorthair cats, accounting for 38.3%, and 252 were Chinese rural cats, accounting for 21.8%. PCR/RT-PCR detection of the above four viruses (FCV, FHV-1, M. felis, and C. felis) in the upper respiratory tract of cats showed that the total positive samples were 744 (64.3%), including 465 positive samples of feline calicivirus, accounting for 40.2% of the total 1158 samples. There were 311 positive samples of M. felis, accounting for 26.9% of the total samples, ranked second in clinical practice. The 180 positive samples of feline herpesvirus accounted for 15.5%, and 85 positive samples of Chlamydia felis accounted for 7.3%. Among them, the number of positive samples of single pathogenic infections was 493, accounting for 66.3% of the total 744 positive samples. Double, triple, and quadruple infections accounted for 28.2%, 5.0%, and 0.5%, respectively, with the highest proportion of single infections. The molecular biological characteristics of the 17 isolated FCVd strains in Wuhan were further analyzed. It was found that the F9 vaccine strain and the antigenic epitopes in the 5'HVR of the E region were collated with the F9 vaccine strain. Moreover, phylogenetic tree analysis showed that the strains related to the F9 and 255 vaccines were distantly related, leading to the failure of the vaccine. In addition, the strains associated with the F9 and 255 vaccines were distant, which might lead to vaccine failure in anticipation of the development of a more phylogenetically close FCV vaccine in China and may require the development of a vaccine for a locally related FCV strain.

Prevalence and characteristics of ocular diseases in Sphynx cats: A retrospective assessment (2012-2021) and comparison with non-Sphynx cats

PURPOSE

To describe the prevalence of ocular diseases in Sphynx cats, and compare disease characteristics with other feline breeds.

METHODS

Medical records of Sphynx cats presented to an ophthalmology referral center between 1/2012 and 4/2021 were examined. Cats of other breeds examined during the same period served as controls.

RESULTS

One hundred ten Sphynx cats were examined during the study period, diagnosed with corneal sequestrum (n = 42 cats), lower eyelid entropion (n = 25), presumed herpetic keratoconjunctivitis (n = 19), conjunctivitis (n = 7), corneal ulcers (n = 6), nasolacrimal duct atresia/obstruction (n = 6), corneal dystrophy (n = 3), eosinophilic keratitis (n = 2), uveitis (n = 2), non-ulcerative keratitis (n = 1), and cataract (n = 1). Corneal sequestrum was significantly more common in Sphynx versus non-Sphynx cats (odds ratio = 8.0, 95% CI = 5.3-12.2, p < .001), and age of diagnosis was significantly younger in Sphynx cats (2.0 ± 1.5 years vs. 5.9 ± 4.0 years, p < .001). Corneal sequestrum recurrence was noted in 19.4% Sphynx eyes and 6.4% non-Sphynx eyes undergoing surgery (p = .015). Lower eyelid entropion-most often bilateral (80%)-was significantly more common in Sphynx versus non-Sphynx cats (odds ratio = 4.1, 95% CI = 2.3-7.1, p < .001), and age of diagnosis was significantly younger in Sphynx cats (0.9 ± 1.4 years vs. 3.5 ± 3.3 years, p < .005).

CONCLUSIONS

Corneal sequestrum and entropion were overrepresented and diagnosed at an earlier age in Sphynx cats when compared with the general feline population. Given the high prevalence, early age of onset, and relatively high recurrence of corneal sequestrum in Sphynx cats, further studies are warranted to better understand etiopathogenesis and preferred therapies.

First Report of Isolation and Molecular Characterization of Felid Herpesvirus-1 from Symptomatic Domestic Cats in Egypt

Feline herpesvirus 1 (FHV-1) is one of the main causes of upper respiratory tract infection in cats. Despite its veterinary importance, no previous studies investigated the occurrence of this virus in Egypt. In the present work, a total number of one hundred forty (N = 140) conjunctival and/or oropharyngeal swabs were collected from symptomatic cats during veterinary clinic visits located in two Egyptian provinces. Virus isolation was performed in the Chorioallantoic membranes (CAMs) of 12-days-old SPF eggs. Interestingly, the embryos showed stunting growth and abnormal feathering and infected CAMs showed edematous thickening and cloudiness with characteristic white opaque pock lesions. Polymerase chain reaction (PCR) amplification of the thymidine kinase gene (TK) was successful in 16/140 (11.4%) of the suspected cases. Two of the amplified genes were sequenced and the TK gene sequences of the FHV-1 isolates were highly similar to other reference strains in the GenBank database. Given the above information, the present study represents the first report of feline herpesvirus type 1 (FHV-1) in domestic cats in Egypt. Further studies on the causes of upper respiratory tract infections in cats as well as vaccine efficacy are needed.

Development and Application of a Triplex TaqMan Quantitative Real-Time PCR Assay for Simultaneous Detection of Feline Calicivirus, Feline Parvovirus, and Feline Herpesvirus 1

As companion animals, felines play an important role in human's family life, and their healthcare has attracted great attention. Viruses such as feline calicivirus (FCV), feline herpesvirus 1 (FHV-1), and feline parvovirus virus (FPV) are the most common pathogens that cause severe infectious disease in baby cats. Thus, preclinical detection and intervention of these three viruses is an effective means to prevent diseases and minimize their danger condition. In this study, a triplex TaqMan quantitative real-time polymerase chain reaction (qRT-PCR) assay was developed to detect these three viruses simultaneously. The detection limit of FPV, FCV, and FHV-1 was 5 × 10¹ copies/assay, which exhibited higher sensitivity (about 10- to100-fold) than conventional PCR. The coefficients of variation (CVs) of the intra-assay variability were lower than 1.86%, and that of inter-assay variability were lower than 3.19%, indicating the excellent repeatability and reproducibility of the triplex assay. Additionally, the assay showed good specificity. Finally, samples from 48 cats were analyzed using the established assay and commercial kits. As a result, the total positive rates for these viruses were 70.83 or 62.5%, respectively, which demonstrated that the developed qRT-PCR assay was more accurate than the commercial kits and could be used in clinical diagnosis.

Pathogenetic role of Staphylococcus aureus in purulent keratoconjunctivitis in cats

The research was carried out in the Department of Surgery and Obstetrics of Agricultural Animals of Dnipro State Agrarian and Economic University on clinically healthy outbred cats of different ages with purulent keratoconjunctivitis. Hematological, biochemical and immunological parameters were determined in the animals, and microbiological and virological research was conducted on them. According to the data obtained, more than half of cases of ophthalmopathology in cats were conjunctivitis and keratoconjunctivitis, and they were more often registered in the cold season. The main causes of eye diseases in the cats were mechanical injuries, coccal and chlamydial infection, allergy and development of disease against the background of primary lesions of the ears and paranasal sinuses. Among the detected microorganisms, the vast majority (81.9%) were staphylococci, including S. albus, S. aureus and S. epidermidis. All types of microorganisms except O-forms of Bacillus sp. exhibited high and medium sensitivity to antibiotics. Immunoblotting revealed polypeptides that responded to specific S. aureus antigens in samples of conjunctiva, cornea, intraocular fluid, and blood of cats suffering from purulent (staphylococcal) keratoconjunctivitis. The highest antigen concentration was detected in the cornea and conjunctiva. In the absence of expressive shifts of the investigated hematological and biochemical parameters, the dynamics of immunological markers were shown by a significant increase in the content of immunoglobulins and circulating immune complexes, as well as by a distinct activation of the complement system by the classical route. The results showed a clear gradual activation of phagocytosis, namely: the number of phagocytic neutrophils increased, reaching its maximum value by the seventh day of development of purulent keratoconjunctivitis. The phagocytic index in the first three days of observation tended to decrease, and by the seventh day it had already significantly exceeded the initial value. Despite the ambiguous dynamics of the phagocytic index, in the course of the development of the inflammatory process in the blood of sick cats, we observed a clear increase in the index of complete phagocytosis. Thus, the development of purulent keratoconjunctivitis in cats occurs against the background of clear cellular and humoral responses to the infectious agent.

A virome sequencing approach to feline oral squamous cell carcinoma to evaluate viral causative factors

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A comprehensive high-throughput viral sequencing strategy (ViroCap) was adapted for use with feline tumors.

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Papillomavirus was not commonly associated with feline oral squamous cell carcinoma.

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Feline oral squamous cell carcinoma is a good model for HPV-negative head and neck squamous cell carcinoma in people.

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The virome of FOSCC and normal feline oral mucosa included feline foamy virus, torque teno virus, herpes and papillomavirus, FIV and EBV.

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Co-occurrence of Epstein Barr Virus and feline papillomavirus-3 was found found in a feline oral squamous cell carcinoma sample.

Feline oral squamous cell carcinoma (FOSCC) may be the best naturally-occurring model of human head and neck squamous cell carcinoma (HNSCC). HNSCC can be broadly divided into human papillomavirus (HPV)-negative cancers and HPV-positive cancers where HPV is the causative agent. Previous studies in FOSCC have used both species-specific and species-nonspecific PCR primers that may be insensitive to the detection of PVs and other viruses that may be divergent from known sequences. ViroCap is a targeted capture and next generation sequencing tool that was designed to identify all known vertebrate DNA and RNA viruses. In this study we used a metagenomic approach using ViroCap for DNA viruses in 20 FOSCC, 9 normal feline oral mucosal, and 8 suspected PV positive control samples. We tested the hypothesis that viruses would be enriched in FOSCC compared to normal oral mucosa. The virome of the FOSCC and normal feline oral mucosa consisted of feline foamy virus in 7/20 and 2/9 (35% and 22%), feline torque teno virus in 2/20 and 0/9 (10% and 0%), alphaherpesvirus in 2/10 and 0/9 (10% and 0%), FIV (0% and 22%), Epstein-Barr virus in 1/20 and 0/9 (5% and 0%) and feline papillomavirus in 1/20 and 0/9 samples (5% and 0% respectively). Felis catus papillomavirus-3 was found in 1 of 20 FOSCC samples. A virus was not associated consistently with FOSCC. If PVs have a role in FOSCC it is at most a supplementary or uncommon role. FOSCC appears most closely related to HPV-negative HNSCC. Future research on FOSCC should focus on identifying genetic and environmental causes.

Cutaneous Hypersensitivity Dermatoses in the Feline Patient: A Review of Allergic Skin Disease in Cats

Feline allergic skin disease presents a unique set of challenges to the veterinary practitioner. Although there is some similarity to what is seen in the allergic canine patient, cutaneous hypersensitivity dermatoses in cats can manifest with strikingly different clinical signs, treatment options and outcomes, and secondary complications/disease entities. Additionally, less is known about the pathogenesis of feline allergic skin diseases, particularly "feline atopic syndrome" when compared to dogs or people. This article aims to review what is currently known in regards to allergic skin disease in the feline patient, with focus on non-flea, non-food hypersensitivity dermatitis.

Superficial keratectomy for chronic corneal ulcers refractory to medical treatment in 36 cats

OBJECTIVE

To review the outcome of a case series in which superficial keratectomy was used as a treatment for chronic corneal ulceration.

STUDY DESIGN

Retrospective study

ANIMALS STUDIED

Thirty-six cats (41 eyes) with ulcerative keratitis.

RESULTS

Forty-one superficial lamellar keratectomies were performed. Thirty-two and a half percent (32.5%) of the ulcers were resolved within 2 weeks and 85% within 4 weeks after surgery. Nonhealing surgical cases after 4 weeks (13% of the eyes) resolved with prolonged postoperative medical treatment. The mean time to healing was 22.1 days (range 7-74 days). At the end of the follow-up period (mean 8.9 months, range 1-36 months), 82.5% of eyes had regained very good to excellent corneal transparency. Nine cases relapsed (21.9% of the eyes) after surgery. Of those cases, the cornea of eight cats healed after undergoing medical treatment, and one underwent a second limited superficial lamellar keratectomy.

CONCLUSION

Superficial keratectomy in cats is an effective treatment to resolve chronic ulcerative keratitis refractory to medical treatment.

Feline calicivirus: a neglected cause of feline ocular surface infections?

OBJECTIVE

To investigate the prevalence of feline calicivirus (FCV) infection in relation to ocular surface lesions in cats with upper respiratory tract diseases (URTD).

ANIMALS STUDIED

Ninety-nine cats with ocular surface infection and symptoms or recent history of URTD were examined at various rescue shelters and hospitals.

PROCEDURE

A complete general and ophthalmic examination was performed including Schirmer tear test, slit-lamp biomicroscopy, fluorescein and lissamine green staining. Clinical and ocular symptoms were scored and recorded. Conjunctival samples were collected using a cytobrush, and nucleic acid extraction using RT-PCR was carried out to analyze for the presence of various infectious agents.

RESULTS

RT-PCR detected either FCV, feline herpes virus type 1 (FHV-1), Chlamydophila felis or Mycoplasma spp. in 63/99 samples. 30/63 samples were positive for FCV, 23/63 for C. felis, 21/63 for Mycoplasma spp., and 16/63 for FHV-1. Out of the 30 FCV-positive samples, 11 were positive only for FCV and in 19 samples FCV was seen in combination with other agents. FCV infection was highest in animals examined at the rescue centers and in the age group of 0-2 months. Erosive conjunctivitis was an important ocular finding. Oral ulcers were detected in all FCV-infected cats.

CONCLUSION

Results indicate that FCV is highly prevalent in cats with URTD either as a sole infectious agent or in combination with other pathogens and therefore is a potential cause for ocular surface lesions during the URTD.

Feline respiratory disease complex

Feline respiratory disease complex (FRDC) refers to the characteristic acute presentation of a contagious respiratory or ocular disease caused by one or multiple pathogens. Environmental and host factors impact the transmission, clinical presentation, preventive strategy, and treatment of affected cats. The FRDC is especially problematic in settings where large numbers of cats cohabit, including animal shelters, catteries, and semi-feral colonies. Although elimination of FRDC is an unrealistic goal, improved understanding can lead to strategies to minimize disease impact.

Development and evaluation of a real-time polymerase chain reaction method for the detection of Mycoplasma felis

Infection by Mycoplasma felis is associated with ocular and respiratory disease in cats and respiratory disease in horses. A correct diagnosis is beneficial since the use of specific antimycoplasmal treatment can lead to resolution. The objective of the present study was to develop a real-time polymerase chain reaction (PCR) method based on dual-labeled fluorogenic probe technology, targeting the gene encoding elongation factor Tu (tuf ), for the fast and specific detection of M. felis. Specificity was achieved by basing the assay design on partial sequencing of the tuf gene in strains and clinical isolates of M. felis as well as other mycoplasma species. The detection limit of the developed assay was in the order of 10 copies of target DNA, and no cross-reaction was observed with a panel of several mycoplasma species. Compared to a previously published conventional PCR protocol, the novel assay had equal or slightly improved performance in terms of sensitivity and specificity when analyzing 100 conjunctival swab samples from cats with clinical signs of infection.

Infectious causes for feline upper respiratory tract disease – a case–control study

The aim of this case–control study was to investigate the prevalence of microorganisms in group-living cats with clinical signs of upper respiratory tract disease (URTD), in in-contact cats and in cats in groups without URTD problems. Samples were taken from the ventral conjunctival fornix for analysis of feline herpesvirus-1 (FHV), Mycoplasma felis and Chlamydiaceae using a real-time polymerase chain reaction technique. The oropharynx was sampled for bacteriological culture and viral isolation. Specific infectious agents were identified in 11/20 (55%) of the case households, in 7/20 (35%) of the cats with clinical signs and in 3/20 (15%) of the control households, in 3/40 (7.5%) of the cats. Chlamydiae and M felis were only detected from case households, both from cats with URTD and from in-contact cats. The difference in prevalence between case and control households was statistically significant for M felis (P=0.047). The presence of M felis in cat groups was thus associated with clinical signs of URTD.