Glycan moiety modifications of feline alpha1-acid glycoprotein in retrovirus (FIV, FeLV) affected cats

alpha1-Acid glycoprotein (AGP) is considered one of the major acute phase proteins in cats. In humans, AGP is a heavily glycosylated protein that undergoes several modifications of its glycan moiety during acute and chronic inflammatory pathologies. In this paper we present the feline AGPs (fAGP) glycan moiety modifications in the course of two prevalent feline diseases, the FIV (feline immunodeficiency virus) dependent feline acquired viral immunodeficiency and the feline leukemia virus (FeLV) associated lymphoma. The glycan moiety of fAGP was investigated by means of the binding of its oligosaccharides residues with specific lectins. Four lectins were used: Sambucus nigra agglutinin I and Maackia amurensis agglutinin lectins were used to detect sialic acid residues, Aleuria aurantia lectin was used to detect L-fucose residues and Concanavalin A was used to evaluate the degree of branching. It was found that fAGP undergoes several post-translational modifications of its glycan pattern: in particular the degree of sialylation is increased in FeLV-positive cats diagnosed with lymphoma, while FeLV-positive that did not presented any specific clinical signs cats do not present any increase of expression of sialic acid on the surface. Furthermore, FIV induced a modification of the glycan moiety of fAGP, which however varied widely among individuals. In order to determine the number and the position of oligosaccharide chains, the cDNA sequence of fAGP was also determined. The translation of the mature fAGP coding sequence gave rise to a sequence of 183 residues, with five potential N-glycosylation sites, but also with seven potential phosphorylation sites.     

Therapeutic effects of recombinant feline interferon-omega on feline leukemia virus (FeLV)-infected and FeLV/feline immunodeficiency virus (FIV)-coinfected symptomatic cats

The clinical efficacy of a recombinant feline interferon, rFeIFN-omega, was evaluated for the treatment of cats presented with clinical signs associated with feline leukemia virus (FeLV) infection and FeLV/feline immunodeficiency virus (FIV) coinfection in the field. In this multicentric, double-blind, placebo-controlled trial, 81 cats meeting the inclusion criteria were randomly placed into 2 groups and treated subcutaneously with rFelFN-omega (1 million [M]U/kg per day) or placebo once daily for 5 consecutive days in 3 series (day 0, 14, 60). The cats were monitored for up to 1 year for clinical signs and mortality. During the initial 4-month period, interferon (IFN)-treated cats (n = 39) had significantly reduced clinical scores compared with placebo (n = 42), with all cats having received concomitant supportive therapies. Compared with the control, the IFN-treated group showed significantly lower rates of mortality: 39% versus 59% (1.7-fold higher risk of death for controls) at the 9-month time point and 47% versus 59% (1.4-fold higher risk of death for controls) at the 12-month time point. The IFN treatment was associated with minor but consistent improvement in abnormal hematologic parameters (red blood cell count, packed cell volume, and white blood cell count), apparently underlying the positive effects of IFN on clinical parameters. These data demonstrate that rFeIFN-omega initially has statistically significant therapeutic effects on clinical signs and later on survival of cats with clinical signs associated with FeLV infection and FeLV/FIV coinfection.     

Seroprevalence of feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) in shelter cats on the island of Newfoundland,Canada

Feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) are retroviruses found within domestic and wild cat populations. These viruses cause severe illnesses that eventually lead to death. Housing cats communally for long periods of time makes shelters at high risk for virus transmission among cats. We tested 548 cats from 5 different sites across the island of Newfoundland for FIV and FeLV. The overall seroprevalence was 2.2% and 6.2% for FIV and FeLV, respectively. Two sites had significantly higher seroprevalence of FeLV infection than the other 3 sites. Analysis of sequences from the FeLV env gene (envelope gene) from 6 positive cats showed that 4 fell within the FeLV subtype-A, while 2 sequences were most closely related to FeLV subtype-B and endogenous feline leukemia virus (en FeLV). Varying seroprevalence and the variation in sequences at different sites demonstrate that some shelters are at greater risk of FeLV infections and recombination can occur at sites of high seroprevalence.     

Prevalence of and factors associated with feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) in cats of the state of Santa Catarina,Brazil

A cross-sectional study was conducted in 274 cats for determination of FeLV antigenemia and FIV seropositivity and factors associated with those infections in cats presented at the Veterinary Hospital of the Santa Catarina State University - UDESC (Brazil). Apparent prevalence for sick cats at the hospital population was 28.41% (95%CI 21.88–34.94%) for FeLV, 7.65% (95%CI 3.71–11.50%) for FIV and 2.18% (95%CI 0.56–5.47%) for both viruses. For healthy cats, the apparent prevalence was 9.89% (95%CI 3.75–16.02%) for FeLV, 2.20% (95%CI 0.34–7.75%) for FIV by immunoassay (ELISA). Average age for FeLV- and FIV-positive individuals was 38.32 and 64.25 months, respectively. Behavior such as aggressiveness and sex (male) were both associated with increased odds of result positivity test for FeLV and FIV; older animals were also associated with FIV test results. A very small proportion of the animals were vaccinated against FeLV and none against FIV. Most of the animals were adopted from shelters or rescued from streets, living with multiple cats that had access to outdoors. The high prevalence of FeLV suggests a need for better control strategies against this disease.     

A survey of FIV antibodies and FeLV antigens in free-roaming cats in the capital area of Finland.

Feline immunodeficiency virus (FIV) was first isolated and identified in 1986. Since then it has been shown to have a worldwide distribution, and the infection generally appears to have reached a state of endemicity. This is the 1st study of FIV-prevalence in Finland. Serum samples of 196 free-roaming cats were tested for antibodies to FIV and FeLV antigens (Feline leukemia virus). With a combined enzyme-linked immunosorbent assay (ELISA), 13 of the cats (6.6%) turned out to be positive for FIV and 2 for FeLV (1.0%). Adult male cats in the capital area of Finland had a FIV prevalence of 24%, a relative proportion 4.7 times higher than that for females.     

Coinfection of Leishmania chagasi with Toxoplasma gondii, Feline Immunodeficiency Virus (FIV) and Feline Leukemia Virus (FeLV) in cats from an endemic area of zoonotic visceral leishmaniasis

The aim of the present study was to determine the coinfection of Leishmania sp. with Toxoplasma gondii, Feline Immunodeficiency Virus (FIV) and Feline Leukemia Virus (FeLV) in a population of cats from an endemic area for zoonotic visceral leishmaniasis. An overall 66/302 (21.85%) cats were found positive for Leishmania sp., with infection determined by direct parasitological examination in 30/302 (9.93%), by serology in 46/302 (15.23%) and by both in 10/302 (3.31%) cats. Real time PCR followed by amplicon sequencing successfully confirmed Leishmania infantum (syn Leishmania chagasi) infection. Out of the Leishmania infected cats, coinfection with FIV was observed in 12/66 (18.18%), with T. gondii in 17/66 (25.75%) and with both agents in 5/66 (7.58%) cats. FeLV was found only in a single adult cat with no Leishmania infection. A positive association was observed in coinfection of Leishmania and FIV (p<0.0001), but not with T. gondii (p>0.05). In conclusion, cats living in endemic areas of visceral leishmaniasis are significantly more likely to be coinfected with FIV, which may present confounding clinical signs and therefore cats in such areas should be always carefully screened for coinfections.     

Serological survey of Toxoplasma gondii, Dirofilaria immitis, Feline Immunodeficiency Virus (FIV) and Feline Leukemia Virus (FeLV) infections in pet cats in Bangkok and vicinities, Thailand

The seroprevalence of Toxoplasma gondii, Dirofilaria immitis (heartworm), feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) infections was examined using serum or plasma samples from 746 pet cats collected between May and July 2009 from clinics and hospitals located in and around Bangkok, Thailand. The samples were tested for heartworm, FIV, and FeLV using a commercial ELISA. Of the 746 samples, 4.6% (34/746) were positive for heartworm antigen, 24.5% (183/746) had circulating FeLV antigen, and 20.1% (150/746) had antibodies against FIV. In addition, the first 348 submitted samples were tested for T. gondii antibodies using a modified agglutination test (MAT, cut off 1:25); 10.1% (35/348) were seropositive. Of the 348 cats sampled for all four pathogens, 11, 10, and 1 were positive for T. gondii antibodies and FIV antibodies, FeLV antigen, or D. immitis antigen, respectively. Of the 35 T. gondii-seropositive cats, 42.9% (15/35) were co-infected with at least one of the other three pathogens. The presence of antibodies to FIV was significantly associated with both age and gender, while FeLV antigen presence was only associated with age. In the case of FIV, males were twice as likely to be infected as females, and cats over 10 years of age were 13.5 times more likely to be infected than cats less than 1 year of age. FeLV antigen was more common in younger cats, with cats over 10 years of age being 10 times less likely to be FeLV positive than cats under 1 year of age. This is the first survey for these four pathogens affecting feline health in Thailand.     

Diseases associated with spontaneous feline leukemia virus (FeLV) infection in cats

More than 2000 cats sent for necropsy in order to provide a diagnosis were investigated immunohistologically using paraffin sections for the presence of a persistent infection with feline leukemia virus (FeLV). The spectrum of neoplastic and non-neoplastic diseases associated significantly with FeLV infection was determined statistically. Three-quarters of the cats with persistent FeLV infections died of non-neoplastic diseases and about 23% died of tumors, nearly exclusively those of the leukemia/lymphoma disease complex. A strong association with liver degeneration, icterus and a FeLV-associated enteritis was found in addition to the known association with non-neoplastic diseases and conditions such as anemia, bacterial secondary infections and respiratory tract inflammations due to the immunosuppressive effect of FeLV, hemorrhages and feline infectious peritonitis. Surprisingly, diseases and conditions like feline infectious panleukopenia, enteritis (of other types than FeLV-associated enteritis and feline infectious panleukopenia), glomerulonephritis, uremia and hemorrhagic cystitis were not associated with persistent FeLV infection. Another unexpected finding was that most pathogenic infectious agents demonstrated in the cats were not FeLV-associated either. Thus, immunosuppression due to FeLV infection seems to make the animals susceptible to certain pathogenic infectious agents, but not to the majority.     

Plasma electrophoretogram in feline immunodeficiency virus (FIV) and/or feline leukaemia virus (FeLV) infections

The electrophoretogram of 89 cats, including those infected by feline immunodeficiency virus (FIV+), feline leukaemia virus (FeLV+) and non-infected, showed statistically significant differences in several of the fractions. FIV+ cats had very high protein values (mean, 8.10 g/dl), mostly because of hypergammaglobulinemia (mean, 2.81 g/dl) as compared with non-infected animals and FeLV+. In addition, in these FIV+ animals, the albumin/globulins ratio (A/G) was very low (mean, 0.72). Statistically significant differences in A/G and alpha2-globulin fraction were observed in FeLV+ group (A/G mean, 0.88 +/- 0.08; alpha2-globulin, mean, 0.84 +/- 0.07 g/dl) when compared with non-infected group (A/G mean, 1.06 +/- 0.08; alpha2-globulin mean, 0.68 +/- 0.04 g/dl). The alpha1-globulin fraction was higher in double infected animals (FIV and FeLV positive, F-F) (3.55 g/dl), than in FeLV+ or FIV+ cats (3.10 and 3.07 g/dl respectively), but no statistical conclusions may be drawn from this fact because of the low number of F-F animals. This technique may help to assess the initial clinical status of retrovirus-infected cats, and the clinical course of these chronic diseases, specifically during and after suitable therapy.     

Feline leukaemia virus (FeLV) and feline immunodeficiency virus infections in cats in the Pisa district of Tuscany, and attempts to control FeLV infection in a colony of domestic cats by vaccination

The seroprevalence of feline immunodeficiency virus (FIV) in 203 apparently healthy domestic cats living in the district of Pisa, central Italy, was 11.3 per cent, and the prevalence of feline leukaemia virus (FeLV) was 8.4 per cent. The prevalence of FIV depended significantly on the lifestyle and age of the cats; cats living outdoors were more likely to be FIV-positive than cats living indoors, and the proportion of FIV-positive cats increased with age. In contrast, there was no significant relationship between these variables and the prevalence of FeLV. There was no significant relationship between the cats' seropositivity for FIV and FeLV. The results of a five-year field study to control FeLV infection by vaccination in a colony of 30 domestic adult cats naturally exposed to the infection suggest that the vaccination was effective in FIV-negative cats, but failed to protect FIV-positive cats against FeLV.     

Evaluation of a novel nested PCR for the routine diagnosis of feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV)

Laboratory diagnosis of feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) usually involves both viruses, as the clinical signs are similar and coinfection may occur. Serological methods may not represent an accurate diagnosis: maternal antibodies or cross-reactions may give false positive results to FIV, and false negative results may occur in latent FeLV status, or in certain FIV infection stages. A nested polymerase chain reaction (PCR) technique was designed to detect FeLV, FIV and feline endogenous retrovirus simultaneously. The detection of endogenous sequences was considered indicative of successful DNA extraction. The technique was used to diagnose FIV and FeLV in the blood cells of 179 cats. The kappa value with the serological data was 0.69 for FeLV and 0.87 for FIV. The joint detection of FeLV and FIV by this novel nested PCR is sensitive, specific, fast and convenient, and its applicability for clinical diagnosis is promising, as the direct evidence of the presence of the virus is more realistic than the indirect data provided by the serological detection.     

The presence of leukaemia (lymphosarcoma) and feline leukaemia virus (FeLV) in cats in The Netherlands

To study the presence and spread of feline leukaemia virus (FeLV) in The Netherlands, seven different groups of cats were examined. The indirect fluorescent antibody (IFA) test was used to detect FeLV-antigen in blood smears. Of cats with lymphosarcoma/leukaemia 73.2% were positive and 32.4% with infectious peritonitis were positive. Only one of sixty-six cats with other tumours–a cat with mammary carcinoma–was positive.
Forty-two (7.5%) of 557 cats with various complaints were positive for FeLV-antigen. The IFA-test appeared to be an important diagnostic supplement.
Of all stud males which had had contact with FeLV-positive cats 24.7% were positive for FeLV-antigen, whereas all stud males which had not had this contact, were negative.
There was a distinct difference between the percentages of FeLV-positive individuals in the groups of cats which had had (20.6%) and which had not had (0.4%) contact with FeLV-positive cats.
From the follow-up study it was found that 67.3% of the FeLV-positive cats died from, or were destroyed because of, FeLV-associated diseases within a period of 20 months.     

Vaccination of cats against feline immunodeficiency virus (FIV): a matter of challenge.

So far, most apparently successful immunodeficiency virus vaccines have only been tested against challenge with cell culture-adapted virus. However, even live priming of cats with feline herpesvirus (FHV) vectors expressing the FIV gag and env gene followed by inactivated booster vaccination with fixed FIX infected cell vaccine proved non-protective against infection with a primary FIV isolate. An effective FIV vaccine for field applications therefore is still not underway.     

Recombinant feline leukemia virus (FeLV) variants establish a limited infection with altered cell tropism in specific-pathogen-free cats in the absence of FeLV subgroup A helper virus

Feline leukemia virus subgroup B (FeLV-B) is commonly associated with feline lymphosarcoma and arises through recombination between endogenous retroviral elements inherited in the cat genome and corresponding regions of the envelope (env) gene from FeLV subgroup A (FeLV-A). In vivo infectivity for FeLV-B is thought to be inefficient in the absence of FeLV-A. Proposed FeLV-A helper functions include enhanced replication efficiency, immune evasion, and replication rescue for defective FeLV-B virions. In vitro analysis of the recombinant FeLV-B-like viruses (rFeLVs) employed in this study confirmed these viruses were replication competent prior to their use in an in vivo study without FeLV-A helper virus. Eight specific-pathogen-free kittens were inoculated with the rFeLVs alone. Subsequent hematology and histology results were within normal limits, however, in the absence of detectable viremia, virus expression, or significant seroconversion, rFeLV proviral DNA was detected in bone marrow tissue of 4/4 (100%) cats at 45 weeks postinoculation (pi), indicating these rFeLVs established a limited but persistent infection in the absence of FeLV-A. Altered cell tropism was also noted. Focal infection was seen in T-cell areas of the splenic follicles in 3/4 (75%) rFeLV-infected cats analyzed, while an FeLV-A-infected cat showed focal infection in B-cell areas of the splenic follicles. Nucleotide sequence analysis of the surface glycoprotein portion of the rFeLV env gene amplified from bone marrow tissue collected at 45 weeks pi showed no sequence alterations from the original rFeLV inocula.     

Retrospective study of 46 cases of feline haemobartonellosis in Israel and their relationships with FeLV and FIV infections

Forty-six cats with clinical haemobartonellosis were studied; 75 per cent of the cats of known age were two-and-a-half years old or younger, 50 per cent were intact males and 19.5 per cent were castrated males. The predominant signs of the disease were tachypnoea, lethargy, depression, anorexia, infestation with fleas, pale mucous membranes, icterus, emaciation, dehydration, splenomegaly, anaemia, leucocytosis, increased activities of alanine aminotransferase and aspartate aminotransferase, and azotaemia. Thirty-eight per cent of the cats that were tested for feline leukaemia virus (FeLV) antigen were positive, and 22 per cent of those tested for feline immunodeficiency virus (FIV) antibodies were positive. The prevalence of both FeLV and FIV was much higher than in the general Israeli cat population. The cats infected with both Haemobartonella felis and FeLV had a significantly lower body temperature, were more anaemic and the mean cell volume of their erythrocytes was greater than in the cats with haemobartonellosis alone.     

Diagnosing feline immunodeficiency virus (FIV) infection in FIV-vaccinated and FIV-unvaccinated cats using saliva

We recently showed that two immunochromatography point-of-care FIV antibody test kits (Witness FeLV/FIV and Anigen Rapid FIV/FeLV) were able to correctly assign FIV infection status, irrespective of FIV vaccination history, using whole blood as the diagnostic specimen. A third FIV antibody test kit, SNAP FIV/FeLV Combo (an enzyme-linked immunosorbent assay [ELISA]), was unable to differentiate antibodies produced in response to FIV vaccination from those incited by FIV infection. The aim of this study was to determine if saliva is a suitable diagnostic specimen using the same well characterized feline cohort. FIV infection status of these cats had been determined previously using a combination of serology, polymerase chain reaction (PCR) testing and virus isolation. This final assignment was then compared to results obtained using saliva as the diagnostic specimen utilizing the same three point-of-care FIV antibody test kits and commercially available PCR assay (FIV RealPCR). In a population of cats where one third (117/356; 33%) were FIV-vaccinated, both immunochromatography test kits accurately diagnosed FIV infection using saliva via a centrifugation method, irrespective of FIV vaccination history. For FIV diagnosis using saliva, the specificity of Anigen Rapid FIV/FeLV and Witness FeLV/FIV was 100%, while the sensitivity of these kits was 96% and 92% respectively. SNAP FIV/FeLV Combo had a specificity of 98% and sensitivity of 44%, while FIV RealPCR testing had a specificity of 100% and sensitivity of 72% using saliva. A revised direct method of saliva testing was trialed on a subset of FIV-infected cats (n = 14), resulting in 14, 7 and 0 FIV positive results using Anigen Rapid FIV/FeLV, Witness FeLV/FIV and SNAP FIV/FeLV Combo, respectively. These results demonstrate that saliva can be used to diagnose FIV infection, irrespective of FIV vaccination history, using either a centrifugation method (Anigen Rapid FIV/FeLV and Witness FeLV/FIV) or a direct method (Anigen Rapid FIV/FeLV). Collection of a saliva specimen therefore provides an acceptable alternative to venipuncture (i) in fractious cats where saliva may be easier to obtain than whole blood, (ii) in settings when a veterinarian or trained technician is unavailable to collect blood and (iii) in shelters where FIV testing is undertaken prior to adoption but additional blood testing is not required.     

A phylogenetic study of Feline Immunodeficiency Virus (FIV) among domestic cats in Turkey

Feline Immunodeficiency Virus (FIV) is the most prominent retrovirus in cats. Molecular studies on FIV are of great importance to enable further studies, for example, understanding the pathogenesis and developing improved vaccines. We aimed to elucidate the molecular status of FIV and provide a detailed characterization of FIV in Turkey because at present there is very limited information available in the literature. We also evaluated a potential link between clinical symptoms and FIV subtypes according to results obtained from molecular tests.Whole blood was collected from 200 client-owned domestic cats and molecular diagnosis and characterization was performed. The env, gag and vif gene regions were amplified and sequenced for phylogenetic analysis. We obtained specific amplicons based on bothenvand gag for FIV in 21 cats; only 2 of the 21 positive samples could also be characterized based on the vif gene region. Separate clusters were identified according to previously determined genotyping strategies; however, they were observed in FIV subtype B. The molecular findings of some individual cats were evaluated in conjunction with their clinical symptoms in an attempt to determine potential relationships between the genetic characteristics of FIV and symptoms of disease. As a result, overexpression of the vif gene could be important in leading to serious clinical symptoms.Our results emphasize the necessity of considering FIV in diagnosis and performing the neccesary diagnostics to confirm or rule out FIV infection. The molecular dynamics of FIV should be periodically updated by further analyses to establish a successful prevention strategy.