Detection of feline herpes virus 1 via polymerase chain reaction and immunohistochemistry in cats with ulcerative facial dermatitis, eosinophilic granuloma complex reaction patterns and mosquito bite hypersensitivity

Autophagy up-regulation upon FeHV-1 infection on permissive cells

FeHV-1 is a member of the Herpesviridae family that is distributed worldwide and causes feline viral rhinotracheitis (FVR). Since its relationship with the autophagic process has not yet been elucidated, the aim of this work was to evaluate the autophagy mediated by FeHV-1 and to determine its proviral or antiviral role. Our data showed that autophagy is induced by FeHV-1 in a viral dose and time-dependent manner. Phenotypic changes in LC3/p62 axis (increase of LC3-II and degradation of p62) were detected from 12 h post infection using western blot and immuno-fluorescence assays. In a second step, by using late autophagy inhibitors and inducers, the possible proviral role of autophagy during FeHV-1 infection was investigating by assessing the effects of each chemical in terms of viral yield, cytotoxic effects, and expression of viral glycoproteins. Our findings suggest that late-stage autophagy inhibitors (bafilomycin and chloroquine) have a negative impact on viral replication. Interestingly, we observed an accumulation of gB, a viral protein, when cells were pretreated with bafilomycin, whereas the opposite effect was observed when an autophagy inducer was used. The importance of autophagy during FeHV-1 infection was further supported by the results obtained with ATG5 siRNA. In summary, this study demonstrates FeHV-1-mediated autophagy induction, its proviral role, and the negative impact of late autophagy inhibitors on viral replication.

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.

Modifications of the PI3K/Akt/mTOR axis during FeHV-1 infection in permissive cells

FeHV-1 is the causative agent of infectious rhinotracheitis in cats. The relationship between viral infection and the PI3K/Akt/mTOR pathway, as well as its function in crucial physiological processes like as autophagy, apoptosis or the IFN induction cascade is known for other varicelloviruses. However, there is no information on whether autophagy is activated during FeHV-1 infection nor on how this infection modifies PI3K/Akt/mTOR pathway. In this work, we aim to elucidate the involvement of this pathway during cytolytic infection by FeHV-1 in permissive cell lines. Using a phenotypic approach, the expression of proteins involved in the PI3K/Akt/mTOR pathway was examined by Western blot analysis. The findings demonstrated the lack of modifications in relation to viral dose (except for phospho-mTOR), whereas there were changes in the expression of several markers in relation to time as well as a mismatch in the time of activation of this axis. These results suggest that FeHV-1 may interact independently with different autophagic signaling pathways. In addition, we found an early phosphorylation of Akt, approximately 3 h after infection, without a concomitant decrease in constitutive Akt. This result suggests a possible role for this axis in viral entry. In a second phase, the use of early autophagy inhibitors was examined for viral yield, cytotoxic effects, viral glycoprotein expression, and autophagy markers and resulted in inefficient inhibition of viral replication (12 h post-infection for LY294002 and 48 h post-infection for 3-methyladenine). The same markers were examined during Akt knockdown, and we observed no differences in viral replication. This result could be explained by the presence of a protein kinase in the FeHV-1 genome (encoded by the Us3 gene) that can phosphorylate various Akt substrates as an Akt surrogate, as has already been demonstrated in genetically related viruses (HSV-1, PRV, etc.). For the same reasons, the use of LY294002 at the beginning of infection did not affect FeHV-1-mediated Akt phosphorylation. Our findings highlight changes in the PI3K/Akt/mTOR pathway during FeHV-1 infection, although further research is needed to understand the importance of these changes and how they affect cellular processes and viral propagation.

An unusual case of eosinophilic uveitis in a cat

An 8-year-old female spayed domestic short-haired cat was examined for recurrent unilateral anterior uveitis of 5 month's duration. No underlying cause was found on infectious disease screening. The cat also had a 4-year history of allergic or immune-mediated skin disease that was controlled with corticosteroid injections followed by long-term oral cyclosporine therapy. Medical management with frequent topical anti-inflammatory drugs (prednisolone acetate 1% suspension, diclofenac 0.1% solution) controlled the intraocular inflammation; however, the uveitis would relapse when therapy was discontinued. Eventually, secondary glaucoma developed OD and the eye was enucleated. At the time of surgery, a complete blood count showed a mild eosinophilia. Histopathology revealed a marked panuveitis characterized by an abundant accumulation of mixed inflammatory cells, with a predominantly eosinophilic infiltrate in the anterior chamber, iris, ciliary body, and choroid. No etiologic agents were found on serial sections, and there were no cellular criteria for malignancy noted. Nine months after enucleation, the chronic dermatitis appeared to be in remission despite no further medical management. This is the first known report of a primarily eosinophilic uveitis in a cat with chronic allergic skin disease and may be considered an ocular variant of feline eosinophilic granuloma complex.

Feline lymphoplasmacytic rhinitis (FLPCR): Severity of inflammation correlates with reduced mucosal IgA expression

Feline lymphoplasmacytic rhinitis (FLPCR) is a rare disease with an unclear pathogenesis characterized by lymphoplasmacytic (LPC) inflammation and progressive tissue destruction. Aims were to evaluate specific FLPCR clinical and pathological features to gain insights into disease pathogenesis. Signalment, clinical signs, serology and 47 pin. h biopsies were retrospectively collected from 33 FLPCR and 3 normal cats. Microscopical lesions and immunohistochemistry results utilizing anti-CD3, anti-CD20, anti-FOXP3, anti-feline-IgA, IgG, IgE and anti-FeLV (p27 and gp70), FIV, FCV and, FHV were scored and most were analyzed statistically. The majority of cats were domestic short haired (26/31) with median age of 11 years and a 0.35 F/M ratio. Serology evidenced 3/22 FIV and 1/22 FeLV positive cats. Immunohistochemistry evidenced 1/33 FeLV-p27 positive cats. Common clinical signs were sneezing (19/24 [79 %]), mucous discharge (13/24 [54 %]) and stertor (10/24 [42 %]). In normal tissues, IgAs were expressed in mucin, apical and lateral cell membrane of columnar cells and in periglandular plasma cells. IgGs were expressed in 20-30 % of columnar cells. Number of clinical signs was statistically significantly higher in female cats (p < 0.0001) and was significantly correlated with chronicity (p = 0.004), and IgG scores (p = 0.01). LPC severity scores correlated positively with infiltration of neutrophils (p = 0.015), gland destruction (p = 0.019) and angiogenesis (p = 0.016) and negatively with fibrosis (p < 0.0001). LPC severity scores were also significantly associated to female sex (p = 0.01) and to IgA (p = 0.03), with higher IgA scores associated to lower LPC scores. FLPCR associated to disruption of mucosal defense mechanisms generating cycles of tissue inflammation, tissue damage and repair with progressive loss of function independent from viral infections.

Feline Neuropathic Pain

Neuropathic pain represents the extreme in maladaptive pain processing. In itself, it is a disease in which pain has become exaggerated in some combination of scope, severity, character, field, duration, and spontaneity. It is almost certainly an underappreciated, underdiagnosed cause of possible significant patient morbidity in cats. This article explores the basic mechanisms, recognition, known and suspect syndromes, and prospective treatment of feline maladaptive and neuropathic pain.

Quantitative real time polymerase chain reaction (qRT-PCR) and RNAscope in situ hybridization (RNA-ISH) as effective tools to diagnose feline herpesvirus-1-associated dermatitis

BACKGROUND

Felid herpesvirus type 1 (FHV-1)-associated dermatitis is characterized by facial and nasal involvement; clinical and histopathological manifestations may overlap with other dermatitides.

OBJECTIVE

To evaluate the realibility of qRT-PCR-2^{- ΔΔC q} and RNAscope in situ hybridization (RNA-ISH) methods to diagnose FHV-1-associated dermatitis, in formalin-fixed paraffin-embedded (FFPE) tissues.

ANIMALS

Sixteen FFPE samples from cats with facial dermatitis and four controls were studied.

METHODS AND MATERIALS

Based on histopathological features, cases were separated into: Group 1, samples with herpetic dermatitis (four); Group 2, samples with nonherpetic facial dermatitis (six); Group 3, samples with facial dermatitis of ambiguous nature (allergic or viral) (six); and Group 4, samples from healthy cats (four). A relative quantification using the 2^{- ΔΔC q} method was used to estimate the "upregulation" of each FHV-1 target viral gene copies (glycoprotein-B and thymidine-kinase) relative to reference gene. Detection of FHV-1 mRNA was performed using the RNAscope 2.5 detection kit.

RESULTS

By 2^{- ΔΔC q} analysis, upregulation of both FHV-1 genes was observed in all samples from Group 1 and two of six from Group 3. No upregulation was identified in samples from groups 2 and 4. Positive mRNA hybridization signal was observed in all cases from Group 1 and two cases of Group 3. No positivity was observed in samples from groups 2 and 4.

CONCLUSIONS AND CLINICAL IMPORTANCE

QRT-PCR 2^-ΔΔCq analysis and RNA-ISH can identify the FHV-1 genome as causative agent of the associated dermatitis, even where inclusion bodies are not detectable. Both techniques are functional in retrospective studies, have greater specificity than conventional PCR, and may be proposed for research and diagnostic purposes.

Case report: systemic tuberculosis caused by Mycobacterium bovis in a cat

BACKGROUND

The diagnosis of previous cases of feline tuberculosis in Turkey has been made based solely on pathological changes without isolation of the causative agent. This case report details the first case of feline tuberculosis in Turkey for which the causative agent (Mycobacterium bovis) was confirmed with microbiological isolation, morphological evaluation, molecular (PCR) characterization and antibiotic sensitivity.

CASE PRESENTATION

Systemic tuberculosis was diagnosed via postmortem examination of a 5-year-old stray male cat. Mycobacterium bovis was isolated from the lungs, bronchial and gastrointestinal lymph nodes, kidney and liver. The isolate was defined as M. bovis using the Genotype MTBC assay (Hain Lifescience, Germany), which allows differentiation of species within the Mycobacterium tuberculosis complex with an easy-to-perform reverse hybridization assay. Pathological changes were characterized by multifocal to coalescing granulomatous inflammation in the lungs, liver, lymph nodes and kidneys. Further pathological changes included severe, diffuse, hepatocytic atrophy, periportal fibrosis with lymphohistiocytic infiltration, multifocal lymphohistiocytic interstitial nephritis, mild focal pulmonary anthracosis and mild renal and hepatic amyloidosis. Infection by immunosuppressive viral pathogens including feline herpes virus-1, feline immunodeficiency virus and feline parvovirus virus were ruled out by polymerase chain reaction assay (PCR). The isolated mycobacteria were susceptible to isoniazid, ethambutol, rifampicin or streptomycin.

CONCLUSION

Disseminated M. bovis is a rare infection in cats. Involvement of submandibular lymph nodes suggested that primary transmission might have been the oral route in the present case.

Skin as a marker of general feline health: Cutaneous manifestations of infectious disease

Practical relevance: Infectious disease in feline patients often presents a diagnostic challenge. This article reviews the most relevant viral, bacterial and protozoal diseases and their cutaneous manifestations. Many of the diseases discussed have overlapping presentations or may mimic more common noninfectious disease processes. The purpose of the article is to reinforce knowledge of common and uncommon infectious diseases, help practitioners identify possible infectious dermatoses, create a comprehensive and prioritized differential list, and provide guidance for the diagnosis of these diseases. A working knowledge of these clinical syndromes is important if what is thought to be a case of a common disease does not respond to conventional management.

AUDIENCE

This review is aimed at veterinarians who treat cats and especially those with an interest in feline dermatology. Tables are included to allow the reader to formulate a concise list of differential diagnoses for clinically similar presentations. The diagnostic approach to a case of ulcerative facial dermatitis is reviewed in a Case Notes quiz. Evidence base: This article includes up-to-date information regarding dermatologic manifestations of less commonly encountered feline cutaneous infectious diseases. Information has been drawn from the published, peer-reviewed literature and the most recent textbook chapters with a particular aim of describing and differentiating clinical lesions and the diagnostic approach to cutaneous disease, especially in unusual cases.

Feline Epitheliotropic Mastocytic Conjunctivitis in 15 Cats

Mast cell infiltration occurs in malignant, inflammatory (eg, allergic, infectious), and idiopathic disease processes in humans and animals. Here, we describe the clinical and histological features of a unique proliferative conjunctivitis occurring in 15 cats. Ocular specimens were examined histologically, and polymerase chain reaction (PCR) for feline herpesvirus 1 (FHV-1) was performed on ocular tissues obtained from 10 cats. Cats had a median age of 8 years (range: 7 months-17.5 years). The known median duration of ocular lesions prior to biopsy was 4 months (range: 1 week-3 years). Ocular disease was unilateral in 12 cats, and 9 cats had coexisting corneal disease. Clinically and histologically, proliferative or nodular conjunctival lesions were noted in 13 cats. The nictitating membrane was affected in 10 cats. Histologically, lesions were characterized by mixed inflammatory infiltrates with an abundance of Giemsa-positive and toluidine blue-positive intraepithelial and subepithelial mast cells, marked edema, and papillary epithelial hyperplasia. Feline herpesvirus 1 was demonstrated by PCR in 1 of 10 cats tested. Follow-up information was available for 14 cats: 8 had no recurrence during a median follow-up period of 17.5 months (range: 4.5-30 months), 2 underwent orbital exenteration, 3 had recurrence that was medically managed, and 1 cat had diffuse conjunctivitis at the time of biopsy and recurrence was deemed irrelevant. Various ocular medications were administered before and after surgical biopsy. This condition was designated as feline epitheliotropic mastocytic conjunctivitis, with intraepithelial mast cells being an essential feature and papillary epithelial proliferation being characteristic but not diagnostic alone. The condition appears to be uncommon and benign. Although the cause is unknown, an allergic component is possible.

Erythema multiforme, Stevens-Johnson syndrome and toxic epidermal necrolysis: a comparative review

BACKGROUND

Human erythema multiforme (EM) and Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) are separate conditions. There is no consensus on classification criteria for the eponymous diseases in animals.

RESULTS

Animal EM is very different from 90% of human EM, which is herpes virus associated (HAEM). Animals lack acrally distributed, typical raised targets. Unlike canine parvovirus 'EM', HAEM is not an active infection. Animal EM is often attributed to drugs, but this is rarely proved. Conversely, human and animal SJS/TEN are almost identical, life-threatening disorders of epidermal necrosis and detachment, typically triggered by drugs (occasionally by infectious agents). Both EM and SJS/TEN are mediated by cytotoxic lymphocyte responses against altered keratinocytes (infectious agents or drugs). Apoptosis results from direct cytotoxicity or through soluble mediators, namely Fas ligand, granzymes, perforin and granulysin. Diagnosis in humans is clinicopathological, with emphasis on clinical lesions; histopathology confirms the pathological process as interface (cytotoxic) dermatitis. Human EM is self-limiting; only recurrent and rare persistent cases require antiviral/immunosuppressive therapies. Drug-induced EM responds to drug withdrawal. Idiopathic canine EM (>40%) is usually chronic, refractory to treatment and may represent heterogeneous conditions. Early identification and removal of the causative drug and high-quality supportive care are critical in SJS/TEN. Mortality rate is nevertheless high.

CONCLUSIONS AND CLINICAL IMPORTANCE

(1) Histopathological lesions do not reliably differentiate EM, SJS and TEN. (2) A multicentre study to develop a consensus set of clinical criteria for EM and SJS/TEN in animals is overdue. (3) No adjunctive therapies, including intravenous immunoglobulin and ciclosporin, have met evidence-based standards.

Feline eosinophilic granuloma complex(ities): some clinical clarification

PRACTICAL RELEVANCE

The feline eosinophilic granuloma complex (EGC) comprises a group of clinically well recognised but poorly understood dermatoses that are common in cats. In many cases, lesions are severe and can be accompanied by varying degrees of (and sometimes considerable) pruritus and/or pain. In addition, lesions can be chronic and recurrent. It is, therefore, important to achieve a prompt and accurate diagnosis in order to provide optimal, often life-long, treatment for affected cats.

PATIENT GROUP

There is no age predisposition or well documented breed predilection for the development of EGC lesions in cats. Some studies have reported a possible female predisposition, but this has not been consistently documented.

CLINICAL CHALLENGES

The clinical diagnosis of EGC lesions is usually straightforward, but investigation of the potential underlying aetiology can pose a challenge for the clinician. Information on the indication for various diagnostic tests and their interpretation is lacking, and the tendency for these cases to be managed with chronic medical intervention prior to achieving a definitive diagnosis can further complicate the interpretation of any diagnostic investigation. In addition, successful therapeutic management of these cases can be challenging. Some cats suffer only a single episode of disease that resolves with treatment, while others have recurrent lesions and some of these can be refractory to treatment. The individual variation in both the clinical nature of the disease and the response to therapy could be related to disease severity, but could also be explained by differences in the underlying aetiopathogenesis.

EVIDENCE BASE

This article reviews the published literature to discuss the complex aetiology of the EGC and present an overview of the different clinical presentations and diagnosis. A further and particular aim has been to provide some evidence-based recommendations for the management of this unusual group of dermatoses.