Feline leukemia virus detection in corneal tissues of cats by polymerase chain reaction and immunohistochemistry

Comparative measurement of FeLV load in hemolymphatic tissues of cats with hematologic cytopenias

BACKGROUND

Feline leukemia virus (FeLV) is a serious viral infection in cats. FeLV is found in some tissues, such as spleen, lymph nodes and epithelial tissues. However, there is controversy about the organ in which the virus can be reliably detected in infected cats. The purpose of this study was to determine the level of viral infection in hemolymphatic tissues, including blood, bone marrow and spleen by reverse-transcriptase quantitative polymerase chain reaction (RT-qPCR).

RESULTS

A total of 31 cats with clinical signs of FeLV infection associated with at least a single lineage hematologic cytopenia were included in this study. Peripheral blood, bone marrow and spleen samples were obtained from each cat. Complete blood counts, biochemical tests, and a rapid test to detect FeLV p27 antigen in blood samples of cats were performed. Of 31 cats, 9 had anemia alone, 4 had thrombocytopenia alone, 2 had neutropenia alone, 9 had bicytopenia of anemia and thrombocytopenia, 3 had bicytopenia of anemia and neutropenia, and 4 had pancytopenia. FeLV RNA was then detected by RT-qPCR in the whole blood, bone marrow and spleen. Viral RNA copy numbers were detected in all cats by RT-qPCR whereas 24 out of 31 cats were positive for the serum FeLV antigen. We detected a significantly greater number of viral RNA in the spleen compared with the whole blood and bone marrow.

CONCLUSION

Spleen is a site where FeLV is most frequently detected in cats with hematologic cytopenias.

Clinical, pathological, immunohistochemical and molecular characterization of feline chronic gingivostomatitis

Objectives This study presents the clinical, pathological, immunohistochemical and molecular characterization of 26 cats with feline chronic gingivostomatitis (FCG). Methods Oral mucosal biopsies, blood and swabs were collected from cats presenting with oral lesions. The tissue sections were submitted for histopathology and immunohistochemical analysis for feline calicivirus (FCV), feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV). The swabs were subjected to PCR analysis for FCV, and blood for FeLV and FIV. Results The main clinical findings were dysphagia (88.2%), halitosis (76.5%), sialorrhea (47.1%), weight loss (41.2%), intense oral discomfort (35.3%), oral hemorrhage (17.6%), and lackluster and fragile coat (11.8%). Gross inspection revealed bilateral lesions across the palatoglossal fold to the lateral tongue base. The lesions were diffuse, proliferative, intensely red and friable, and bled easily upon examination in 80.8% of cases. In 23.1% of cases, the lesions were multifocal to coalescent, at times forming multiple vesicles on a reddened, edematous palatoglossal fold. Microscopic examination showed that 15.4% of lesions had moderate (grade 2) and 84.6% had severe (grade 3) inflammation. Immunohistochemistry revealed the presence of FeLV antigens in the epithelium and the inflammatory infiltrate of 30.8% of the cats with FCG. FCV antigens were not detected in the FCG lesions. Conclusions and relevance The FCG cases analyzed could not be correlated with FCV. It is possible that FeLV plays a role as a causal agent of lesions in cases where the presence of the virus has been confirmed by immunohistochemistry in epithelial samples.

Genotyping of feline leukemia virus in Mexican housecats

Feline leukemia virus (FeLV) is a retrovirus with variable rates of infection globally. DNA was obtained from cats' peripheral blood mononuclear cells, and proviral DNA of pol and env genes was detected using PCR. Seventy-six percent of cats scored positive for FeLV using env-PCR; and 54 %, by pol-PCR. Phylogenetic analysis of both regions identified sequences that correspond to a group that includes endogenous retroviruses. They form an independent branch and, therefore, a new group of endogenous viruses. Cat gender, age, outdoor access, and cohabitation with other cats were found to be significant risk factors associated with the disease. This strongly suggests that these FeLV genotypes are widely distributed in the studied feline population in Mexico.

Detection of antibodies to the feline leukemia Virus (FeLV) transmembrane protein p15E: an alternative approach for serological FeLV detection based on antibodies to p15E

The aim of this report was to investigate whether the diagnosis of feline leukemia virus (FeLV) infection by serology might be feasible and useful. Among the various viral proteins, the FeLV env-gene product (SU) and the envelope transmembrane protein p15E were considered promising candidates for the serological diagnosis of FeLV infection. Thus, we evaluated p15E and three other FeLV antigens, namely, a recombinant env-gene product, whole FeLV, and a short peptide from the FeLV transmembrane protein, for their potential to detect FeLV infection. To evaluate possible exposure of cats to FeLV, we tested serum and plasma samples from experimentally and naturally infected and vaccinated cats for the presence of antibodies to these antigens by enzyme-linked immunosorbent assays (ELISAs). The serological results were compared with the p27 and proviral real-time PCR results. We found that p15E displayed a diagnostic sensitivity of 95.7% and a specificity of 100% in experimentally infected cats. In naturally infected cats, p15E showed a diagnostic sensitivity of 77.1% and a specificity of 85.6%. Vaccinated cats displayed minimal antibody levels to p15E, suggesting that anti-p15E antibodies indicate infection rather than vaccination. The other antigens turned out to be too unspecific. The lower specificity in cats exposed to FeLV under field conditions may be explained by the fact that some cats become infected and seroconvert in the absence of detectable viral nucleic acids in plasma. We conclude that p15E serology may become a valuable tool for diagnosing FeLV infection; in some cases, it may replace PCR.

Ocular manifestations of feline viral diseases

Feline viral diseases are common and cats can be presented with a variety of clinical manifestations. Ocular disease associated with viral pathogens is not unusual, particularly with viruses causing upper respiratory tract disease in cats, such as feline herpesvirus type 1 and feline calicivirus. These agents mainly cause ocular surface disease. Other viruses, such as feline immunodeficiency virus and feline coronavirus, can cause uveitis, while feline leukemia virus can induce ocular lymphosarcoma. This review covers the most common viral pathogens of cats that cause ocular manifestations, the specific features of the ocular diseases caused by these viruses and therapeutic recommendations.

The use of porcine small intestinal submucosa for the repair of full-thickness corneal defects in dogs, cats and horses

OBJECTIVE

To evaluate the efficacy of using a porcine small intestinal submucosa (SIS) graft covered by a conjunctival flap for the surgical repair of full-thickness corneal wounds in dogs, cats and horses.

PROCEDURE

All records dating from August 1999 to February 2003 from Purdue University Veterinary Teaching Hospital of patients that had undergone ophthalmic surgical procedures and received a SIS corneal graft for a full-thickness lesion were reviewed. Fifteen cases were identified including six dogs, two cats and seven horses. Requirements for inclusion in this study were that SIS was used as a corneal graft in a full-thickness corneal defect and that the graft was completely covered with a conjunctival flap.

RESULTS

Of the 15 cases, one canine patient had received SIS following removal of an epibulbar melanocytoma. The remaining five canine patients had undergone this surgical procedure for the repair of corneal perforation. The two feline patients had been presented for corneal perforation following chronic ulceration. One equine patient had been presented for a deep melting ulcer, three for stromal corneal abscesses, and three for corneal perforations. Complications encountered postoperatively included aqueous leakage, conjunctival flap dehiscence, synechia, cataract and fibrin in the anterior chamber. Fourteen out of 15 patients were visual at the final re-evaluation.

CONCLUSION

SIS is an inexpensive, easy-to-handle biomaterial that appears to be suitable for the repair of full-thickness corneal wounds in dogs, cats and horses. Results of our study support the conclusion that this relatively new product is an effective alternative to traditional implantation materials utilized in veterinary ophthalmology.

Lack of detection of feline leukemia and feline sarcoma viruses in diffuse iris melanomas of cats by immunohistochemistry and polymerase chain reaction

Diffuse iris melanoma was confirmed by light-microscopic examination in 10 formalin-fixed, paraffin-embedded globes from 10 cats. To determine if feline leukemia virus or a replication defective feline leukemia virus, feline sarcoma virus, was present in these anterior uveal melanomas, immunohistochemistry and polymerase chain reaction for feline leukemia virus were utilized. Immunohistochemical staining for feline leukemia virus glycoprotein 70 was performed on all 10 tumors using an avidin-biotin complex technique. The DNA was extracted from each specimen and a 166-base pair region of the feline leukemia virus long terminal repeat was targeted by polymerase chain reaction. Immunohistochemical staining for feline leukemia virus glycoprotein 70 and polymerase chain reaction amplification of a feline leukemia virus long terminal repeat region were negative in all cases. Feline leukemia virus/feline sarcoma virus was not detected in any neoplasms and therefore was unlikely to play a role in the tumorigenesis of these feline diffuse iris melanomas.