Adjuvant immunotherapy of feline fibrosarcoma with recombinant feline interferon-omega

BACKGROUND: Recombinant feline interferon-omega (rFeIFN-omega) was tested as a treatment option for cats with fibrosarcoma to assess safety and feasibility. HYPOTHESIS: Treatment with rFeIFN-omega in cats with fibrosarcoma is safe and feasible. ANIMALS: Twenty domestic cats. METHODS: In an open-labeled uncontrolled clinical trial 12 injections of 1 x 10(6) U/kg rFeIFN-omega were administered over a 5-week period: the 1st through 4th injections were given intratumorally, and the 5th through 12th injections were administered subcutaneously at the tumor excision site. Wide surgical excision of the tumors was carried out after the 4th injection and before the 5th injection of rFeIFN-omega. A Common Terminology Criteria for Adverse Events (CTCAE) analysis was conducted. Flow cytometry of fibrosarcoma cells after incubation with rFeIFN-omega and recombinant feline interferon-gamma was performed to assess the biological effect of rFeIFN-omega. RESULTS: Changes in blood cell count, increases in serum aspartate-amino-transferase activity, serum bilirubin concentration, serum creatinine and serum electrolyte concentrations, weight loss, anorexia, increased body temperature, and reduced general condition were observed but were mostly minor (grade 1 and 2) and self limiting. Eosinophilia (P = .025), neutropenia (P = .021), and weight loss (P < .001) were statistically correlated with rFeIFN-omega-treatment (analysis of parameters before treatment and after 3 injections of rFeIFN-omega). Flow cytometry of 5 unrelated feline fibrosarcoma cell lines showed increased expression of major histocompatibility complex (MHC) class I molecules (P = .026) in response to in vitro incubation with rFeIFN-omega, whereas expression of MHC class II molecules was not affected significantly. CONCLUSIONS AND CLINICAL IMPORTANCE: RFeIFN-omega for the treatment of feline fibrosarcoma is safe, well tolerated, and can be easily performed in practice. To assess the efficacy of the treatment, it should be tested in a placebo-controlled trial.     

Prevalence of feline leukaemia provirus DNA in feline lymphomas

A significant drop in the prevalence of feline leukaemia virus (FeLV) antigenaemic cats and antigen-associated lymphomas has been observed after the introduction of FeLV vaccination and antigen-testing with removal of persistently antigenaemic cats. However, recent reports have indicated that regressively infected cats may contain FeLV provirus DNA and that lymphoma development may be associated with the presence of provirus alone. In the present study, we investigated the presence of FeLV antigen and provirus DNA in 50 lymphomas by immunohistochemistry and semi-nested polymerase chain reaction, respectively. Interestingly, almost 80% of T-cell lymphomas and 60% of B-cell lymphomas contained provirus DNA while only 21% of T-cell lymphomas and 11% of B-cell lymphomas expressed FeLV antigen. In conclusion, our results support previous hypotheses that vaccination and removal of persistently antigenaemic cats have led to a drop in FeLV antigen-expressing lymphomas. However, FeLV provirus DNA is still present in a high percentage of feline lymphomas.     

Experimentally induced feline chlamydial infection (feline pneumonitis)

Cats exposed to aerosols of feline Chlamydia psittaci developed a disease characterized principally by conjunctivitis. Signs of conjunctivitis appeared between postexposure days (PED) 5 and 10, were often unilateral initially, and persisted for 22 to 45 days. Fever followed the onset of conjunctivitis (PED 11 to 15) and persisted for 3 to 8 days. Signs of mild rhinitis (occasional sneezing and mild serous nasal discharge) occurred in some cats between PED 8 and 37. Neither signs of lower respiratory tract disease nor significant pulmonary lesions were produced by the feline pneumonitis agent. Small foci of pneumonia were detected microscopically in 3 of 6 cats examined between PED 7 and 14. Chlamydiae were identified between PED 7 and 14 in the cytoplasm of epithelial cells in stained conjunctival smears. Conjunctivitis persisted for at least 18 days after chlamydiae no longer were detectable in conjunctival smears. Low levels of chlamydial infectivity, however, still were present in conjunctiva and lung on PED 45.     

Carrier-state infection of feline T-lymphoblastoid cells with feline calicivirus

The susceptibility of feline T lymphocytes to feline calicivirus (FCV) in vitro was investigated using feline T-lymphoblastoid cell lines, namely MYA-1 and FL74 cells. The virus titers of supernatants in FCV-infected MYA-1 and FL74 cell cultures increased rapidly, and FCV antigens were also detected in the FCV-infected cells. There were slight differences in the molecular weights of capsid proteins expressed in FCV-infected MYA-1, FL74 and Crandell feline kidney cells. MYA-1 and FL74 cells were productively and persistently infected with FCV, and FCV antigens were observed in the FCV-infected cells for more than one month. At 3 months post infection, FCV-infected FL74 cells that stopped producing infectious FCV could be reinfected with FCV. However, no cytopathic effects were observed.     

Relevance of feline calicivirus, feline immunodeficiency virus, feline leukemia virus, feline herpesvirus and Bartonella henselae in cats with chronic gingivostomatitis

Despite its common occurrence, the aetiology of chronic gingivostomatitis in cats remains uncertain. Aetiology is likely multifactorial, and several infectious agents may be associated with chronic gingivostomatitis. The purpose of this study was to investigate the prevalence of feline calicivirus (FCV), feline immunodeficiency virus (FIV), feline leukemia virus (FeLV), feline herpesvirus (FHV), and Bartonella henselae (B. henselae) in cats with chronic gingivostomatitis and in an age-matched control group. In addition, other factors, e. g., environmental conditions were investigated. In 52 cats with chronic gingivostomatitis and 50 healthy age-matched control cats, the presence of FCV ribonucleic acid (RNA), and FHV deoxyribonucleic acid (DNA) (polymerase chain reaction [PCR] from oropharyngeal swabs), and B. henselae DNA (PCR from oropharyngeal swabs and blood), as well as FeLV antigen (serum), and antibodies against FCV, B. henselae, and FIV (serum) were examined. FCV RNA was significantly more common in cats with chronic gingivostomatitis (53.8%, p < 0.001) than in controls (14.0%); a significant difference was also found in the prevalence of antibodies to FCV between the cats with chronic gingivostomatitis (78.8%, p = 0.023) and controls (58.0%). Of the other infectious agents investigated, there was no significant difference in the prevalence between the cats with chronic gingivostomatitis and the controls. The results of this study allow the conclusion that FCV, but no other infectious agents, is commonly associated with chronic gingivostomatitis in cats.     

Diagnosis of feline leukemia virus and feline immunodeficiency virus infections

Feline leukemia virus is an oncogenic retrovirus that can result in a wide variety of neoplastic and non-neoplastic diseases, including immunosuppression. Diagnosis of FeLV infection can be achieved by several methods, including virus isolation; IFA assay of a peripheral blood smear; and detection of a viral protein (called p27) by ELISA testing of whole blood, plasma, serum, saliva, or tears. Commercially available ELISA kits have revolutionized FeLV testing and have become very popular as "in-house" procedures. This article discusses the interpretation of ELISA results and compares them with IFA assay findings. Feline immunodeficiency virus is a lentivirus that causes immunosuppression, but not neoplasia, in cats. It originally was called feline T-lymphotropic lentivirus. Differentiating FIV infection from the immunosuppressive type of FeLV infection requires virus isolation or serology. The most rapid method for diagnosis of FIV infection is ELISA testing for antiviral antibody.     

Clinical aspects of feline immunodeficiency and feline leukemia virus infection

Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are retroviruses with a global impact on the health of domestic cats. The two viruses differ in their potential to cause disease. FIV can cause an acquired immunodeficiency syndrome that increases the risk of developing opportunistic infections, neurological diseases, and tumors. In most naturally infected cats, however, FIV itself does not cause severe clinical signs, and FIV-infected cats may live many years without any health problems. FeLV is more pathogenic, and was long considered to be responsible for more clinical syndromes than any other agent in cats. FeLV can cause tumors (mainly lymphoma), bone marrow suppression syndromes (mainly anemia) and lead to secondary infectious diseases caused by suppressive effects of the virus on bone marrow and the immune system. Today, FeLV is less important as a deadly infectious agent as in the last 20 years prevalence has been decreasing in most countries.     

Detection of feline coronavirus antibody, feline immunodeficiency virus antibody, and feline leukemia virus antigen in ascites from cats with effusive feline infectious peritonitis

To investigate the usefulness of ascites as a material for viral tests in cats with effusive feline infectious peritonitis (FIP), we attempted to detect anti-feline coronavirus antibody, anti-feline immunodeficiency virus antibody, and feline leukemia virus antigen in ascites from 88 cats clinically suspected with effusive FIP. In each of these three viral tests, all cats positive for serum antibody/antigen were also positive for ascitic antibody/antigen, while cats negative for serum antibody/antigen were also negative for ascitic antibody/antigen. This finding indicates that ascites is useful for these viral tests.     

Clinical trial of a feline pheromone analogue for feline urine marking

Thirty-six cases of feline urine marking problem were collected through the cooperation of veterinary practitioners in the Kanto, Chubu, and Kansai areas in Japan, for an assessment of the clinical effect of treatment with a synthetic analogue of a feline cheek gland pheromone-like product. The mean frequency of urine marking was 14.2 times/week (median, 10; range, 1-77) at pre-treatment week (preW), and decreased significantly from the first week of treatment, dropping to 4.2 times/week (median, 2; range, 0-44) at the fourth week of treatment. This effect continued until the fourth week after cessation of treatment. These 36 cases were divided into 3 groups based on the effectiveness of treatment as demonstrated in the fourth week of treatment; 37% was categorized as the totally eliminated group (urine marking was not seen), 40% as the reduced group (the frequency of urine marking was equal to or less than 50% that of the preW), and 23% as the unchanged group (the frequency of urine marking was more than 50% that of the preW). Effectiveness of treatment in these groups was 38%, 24%, and 38% at the fourth week after the cessation of treatment, respectively. The decreasing rate of urine marking was compared between cats with and without intercat aggression, and it was revealed that the frequency of marking was sustained at high level in cats with intercat aggression. These results suggest that this pheromone treatment is as effective in Japan as has been reported in other countries for solving feline urine marking problems.     

Onset of immunity in kittens after vaccination with a non-adjuvanted vaccine against feline panleucopenia, feline calicivirus and feline herpesvirus

The induction of a quick onset of immunity against feline parvovirus (FPV), feline herpesvirus (FHV) and feline calicivirus (FCV) is critical both in young kittens after the decline of maternal antibodies and in cats at high risk of exposure. The onset of immunity for the core components was evaluated in 8–9 week old specific pathogen free kittens by challenge 1 week after vaccination with a combined modified live (FPV, FHV) and inactivated (FCV) vaccine. The protection obtained 1 week after vaccination was compared to that obtained when the challenge was performed 3–4 weeks after vaccination. The protocol consisted of a single injection for vaccination against FPV and two injections 4 weeks apart for FHV and FCV.At 1 week after vaccination, the kittens showed no FPV-induced clinical signs or leukopenia following challenge, and after FCV and FHV challenges the clinical score was significantly lower in vaccinated animals than in controls. Interestingly, the relative efficacy of the vaccination was comparable whether the animals were challenged 1 week or 3–4 weeks after vaccination, indicating that the onset of protection occurred within 7 days of vaccination. Following the 1-week challenge, excretion of FPV, FHV and FCV was significantly reduced in vaccinated cats compared to control kittens, confirming the onset of immunity within 7 days of vaccination.