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1.
Activation of protein kinase C by a phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA), was shown to stimulate the respiratory burst in normal cat neutrophils. Neutrophils from feline leukemia virus (FeLV)-exposed viremic and nonviremic cats had significant suppression of their respiratory burst when stimulated with TPA. The addition of whole ultraviolet light-inactivated FeLV and FeLV proteins to normal cat neutrophils produced no significant suppression of the respiratory burst. These data suggest two possible mechanisms for suppression. The first is partially due to viral alterations of the neutrophil as seen in viremic cats, but, because exogenously applied FeLV or FeLV proteins had no effect on the respiratory burst, an additional mechanism is present. The second mechanism may be caused by a latent FeLV infection residing in nonviremic cat bone marrows which alters their immune system, resulting in immunosuppression.  相似文献   

2.
Biological effects of staphylococcal protein A (SPA) immunotherapy were studied in 5 viremic and 6 nonviremic cats with induced FeLV infection and in 6 control cats. The SPA therapy neither reversed FeLV viremia nor resulted in consistent improvement in humoral immune responses to FeLV antigens. However, SPA immunotherapy induced a proliferative response in bone marrow granulocytic lineage, possibly resulting in expression of FeLV-free mature neutrophils in the blood. Seemingly, viral burden and chemiluminescent responses were reversed in viremic cats during SPA immunotherapy.  相似文献   

3.
Fifteen specific-pathogen-free cats were experimentally infected with FeLV; 8 cats recovered after transient or nondetectable viremia, and 7 cats became persistently viremic. Four additional cats served as noninfected controls. Antibodies to whole FeLV (ELISA and immunoblot [western] analysis), antibodies to fixed FeLV-infected cells, and virus-neutralizing antibodies were monitored for as long as 3 years after infection. As a group, cats that recovered after acute infection developed higher titer of these various antibodies than did cats that became persistently viremic. However, specific combination or titer of antibodies was not always found in recovered cats or in persistently viremic cats. Six cats that had recovered from acute FeLV infection nearly 3 years earlier were reinfected with the same virus. Three of the cats appeared to be resistant to reinfection, 2 cats became transiently viremic, and 1 cat became persistently viremic. Slight and transient anamnestic ELISA-detectable antibody response to whole virus was seen after reinfection; immunofluorescence- and western blot-detectable responses were not greatly enhanced. Five FeLV-recovered cats were monitored for 2 years; FeLV infection spontaneously recurred in 1 cat.  相似文献   

4.
Two hundred fifty Boston cats with disorders such as lymphosarcoma, myeloproliferative disease, anemia, glomerulonephritis, pregnancy abnormalities, feline infectious peritonitis, toxoplasmosis, and various bacterial infections were examined for feline leukemia virus (FeLV) by immunofluorescence. Antibody titers against feline oncornavirus-associated cell membrane antigen (FOCMA) were tested in 133 of these cats. The tests for FeLV and FOCMA antibody were also conducted among healthy cats not known to have been exposed to FeLV, as well as among healthy cats from households where FeLV was known to be present. Most of the cats with lymphosarcoma and the other aforementioned disorders were infected with FeLV and low FOCMA antibody titers. Healthy cats known to have been exposed to FeLV were often viremic, but those that remained healthy were able to develop high FOCMA antibody titers. Healthy cats without known prior exposure to FeLV were unlikely to be viremic but often had detectable FOCMA antibody titers, indicating that some exposure occurs under natural conditions in the Boston area. The association of FeLV with infections other than lymphosarcoma was assumed to be caused by the immunosuppresive effect of FeLV, thus allowing development of disease.  相似文献   

5.
Use of tears for diagnosis of feline leukemia virus infection   总被引：2，自引：0，他引：2  
A comparison was made of the use of serum, tears, and saliva for the detection of feline leukemia virus (FeLV) infection in cats. Cotton swabs were used to collect saliva, and tear-test strips were used to collect tears. Specimens were analyzed by a commercially available ELISA. Using a 10- to 15-minute specimen incubation period, FeLV was detected in 70% of the saliva specimens and in 73% of the tear specimens from viremic (serum-positive) cats. Feline leukemia virus antigen was not detected in saliva and tear specimens from serum-negative cats. The sensitivity of the tear assay was improved by increasing the incubation time to 24 hours. Tear strips could be air-dried and stored at room temperature for up to 7 days without any appreciable loss of activity. Client-owned and experimentally infected laboratory cats were tested for FeLV, using air-dried tear-test strips and a 24-hour incubation period. Tears were positive (contained FeLV antigen) in 65 of 72 (90%) serum-positive cats and did not contain antigen in 46 of 46 (100%) serum-negative cats. Results of ELISA obtained from serum and tears also were compared with results obtained from indirect fluorescent antibody testing of blood smears. Results of indirect fluorescent antibody and ELISA compared favorably with each other and with the results of tear testing.  相似文献   

6.
A randomized blind trial of a commercial FeLV vaccine was conducted to evaluate its performance in cats under conditions of long-term natural exposure. Seventy-nine nonviremic, seronegative cats were randomized into 2 groups. Cats were given 3 doses of either FeLV vaccine or placebo (killed rabies virus vaccine) sc at weeks 0, 3, and 9 of the trial. Six weeks later, 44 known-viremic cats were added to the colony. Cats were housed in a single large room and food dishes and litter pans were used in common. Blood samples were collected at 4, 8, and 12 months after the addition of the viremic cats and were assayed for viremia by use of ELISA. Twelve-month samples were also assayed independently by use of indirect fluorescent antibody testing. Investigators conducted assays on coded samples without knowledge of the cat's vaccination status; neither the investigators nor colony personnel knew which cats had been given the FeLV vaccine and which had been given the placebo until the twelfth month of exposure. After 12 months of cohabitation with infected cats, vaccinated cats had a significantly (P less than or equal to 0.02) lower incidence of persistent viremia (defined as 2 positive ELISA test results at least 8 weeks apart or 1 positive indirect fluorescent antibody test result), compared with the placebo-inoculated cats. The incidence of persistent viremia was approximately 3 times greater among the placebo-inoculated cats than among vaccinates.  相似文献   

7.
Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are retroviruses causing significant morbidity and mortality in cats. The aim of this study was to describe the epidemiological, clinical and clinicopathologic aspects of FeLV and FIV infections in different populations of cats in Greece, including client-owned cats, stray cats and cats who live in catteries.A total of 435 cats were prospectively enrolled. Serological detection of FeLV antigen and FIV antibody was performed using a commercial in-house ELISA test kit.The results showed that 17 (3.9 %) and 40 (9.2 %) of the 435 cats were positive for FeLV antigen and FIV antibody, respectively, whereas 5 (1.1 %) had concurrent infection with FeLV and FIV. Factors that were associated with FeLV antigenemia, based on multivariate analysis, included vomiting, rhinitis, infection with FIV, neutropenia, decreased blood urea nitrogen and increased serum cholesterol and triglyceride concentrations. Factors associated with FIV seropositivity included male gender, older age, outdoor access, weight loss, fever, gingivostomatitis, skin lesions and/or pruritus and hyperglobulinemia.Various clinical signs and laboratory abnormalities were found to be significantly associated with retroviral infections, suggesting that current guidelines to test all sick cats should be followed, taking into particular consideration the high-risk groups of cats found in this study.  相似文献   

8.
Cats exposed to feline leukemia virus (FeLV), a naturally occurring gammaretrovirus develop either progressive or regressive infection. Recent studies using analyses with enhanced sensitivity have correlated loads throughout FeLV with the clinical outcome, though remarkably, during the acute phase of infection, proviral and viral RNA burdens in the peripheral blood do not differ between groups. We hypothesized that viral loads in specific leukocyte subsets influence the infection outcome. Using a method established to determine the proviral and cell-associated viral RNA loads in specific leukocyte subsets, we evaluated viral loads in eleven FeLV-exposed specific pathogen-free (SPF) cats 2.5 years post-infection. Six cats had undergone regressive infection whereas five were persistently viremic. Aviremic cats had lower total proviral blood loads than the persistently infected cats and FeLV proviral DNA was shown to be integrated into genomic DNA in four out of four animals. Lymphocytes were predominantly infected vs. moncytes and granulocytes in aviremic cats. In contrast, persistently viremic cats were provirus-positive in all leukocyte subsets. The acute phase kinetics of FeLV infection were analyzed in two additional cats; an early lymphoreticular phase with productive infection in lymphocytes in both cats and in monocytes in one cat was followed by infection of the granulocytes; both cats became persistently infected. These results indicate that FeLV persistent viremia is associated with secondary viremia of bone marrow origin, whereas regressive cats only sustain a non-productive infection in low numbers of lymphocytes.  相似文献   

9.
Most studies that investigate the prevalence of infections with feline leukemia virus (FeLV) are based on the detection of p27 antigen in blood, but they do not detect proviral DNA to identify the prevalence of regressive FeLV infections. The aim of the present study was to assess the prevalence and status of FeLV infection in cats in Southern Germany. P27 antigen enzyme-linked immunosorbent assay (ELISA), anti-p45 antibody ELISA, DNA polymerase chain reaction (PCR) of blood and RNA PCR of saliva were performed. Nine out of 495 cats were progressively (persistently) infected (1.8%) and six were regressively (latently) infected (1.2%). Cats with regressive infections are defined as cats that have been able to overcome antigenemia but provirus can be detected by PCR. Twenty-two unvaccinated cats likely had abortive infections (regressor cats), testing FeLV antigen- and provirus-negative but anti-p45 antibody-positive. Most of the FeLV-vaccinated cats did not have anti-FeLV antibodies. Both progressive, as well as regressive infections seem to be rare in Germany today.  相似文献   

10.
Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are among the most common infectious diseases of cats. Although vaccines are available for both viruses, identification and segregation of infected cats form the cornerstone for preventing new infections. Guidelines in this report have been developed for diagnosis, prevention, treatment, and management of FeLV and FIV infections. All cats should be tested for FeLV and FIV infections at appropriate intervals based on individual risk assessments. This includes testing at the time of acquisition, following exposure to an infected cat or a cat of unknown infection status, prior to vaccination against FeLV or FIV, prior to entering group housing, and when cats become sick. No test is 100% accurate at all times under all conditions; results should be interpreted along with the patient's health and risk factors. Retroviral tests can diagnose only infection, not clinical disease, and cats infected with FeLV or FIV may live for many years. A decision for euthanasia should never be based solely on whether or not the cat is infected. Vaccination against FeLV is highly recommended in kittens. In adult cats, antiretroviral vaccines are considered non-core and should be administered only if a risk assessment indicates they are appropriate. Few large controlled studies have been performed using antiviral or immunomodulating drugs for the treatment of naturally infected cats. More research is needed to identify best practices to improve long-term outcomes following retroviral infections in cats.  相似文献   

11.
The safety and the efficacy of several feline leukemia virus (FeLV) vaccines for 16-week-old kittens were determined. Vaccines were derived from an FL74 lymphoblastoid cell line that has been in continuous tissue culture passage for about 4 years. The vaccines were made from living virus, formaldehyde-inactivated whole FL74 cells, and formaldehyde-inactivated whole virus. The efficacy of each produced vaccine was determined by challenge exposure of vaccinated cats with virulent FeLV. The two formaldehyde-inactivated vaccines were found to be safe for use in kittens. Neither vaccine produce a significant feline oncornavirus-associated cell membrane antigen or virus-neutralizing antibody response, nor did they prevent infection with virulent FeLV. The inactivated whole-virus vaccine, however, did substantially decrease the proportion of kittens infected with virulent FeLV that became persistently viremic. In contrast, the whole FL74 cell vaccine did not reduce the number of infected kittens that became persistently viremic. The live-virus vaccine was found to be both safe and efficacious. About a half of the kittens vaccinated with live virus had transient bone marrow infection that lasted from 2 to 4 weeks. Viral antigen was not detected in peripheral blood, and infective virus was not shed in saliva, urine, or feces during the period that the vaccinal virus could be recovered from the bone marrow. In addition, there was no horizontal spread of vaccinal virus from vaccinated to non-vaccinated cagemates. Within several weeks, vaccinated kittens demonstrated no clinical or hematologic abnormalities and had high serum levels of feline oncornavirus-associated cell membrane antigen and virus-neutralizing antibody. Kittens vaccinated with living FeLV were resistant to infection with virulent virus.  相似文献   

12.
Monoclonal antibodies specific for 3 distinct epitopes of the species-specific determinants of feline leukemia virus (FeLV) p27 were used in an enzyme-linked immunosorbent assay (ELISA) for measurement of serum p27 in cats infected with FeLV. Group-specific antigen (GSA) of FeLV in peripheral blood leukocytes was also determined by an immunofluorescence assay. Antibodies to FeLV and the feline oncornavirus-associated cell membrane antigen (FOCMA) were also measured. Thirty-six cats were surveyed and assigned to 4 categories. Five developed persistent viremia (category 1), characterized by continuous expression of p27, GSA, and low antibody titers to FeLV and FOCMA. Eleven cats with transient viremia (category 2) and 13 cats that were never detectably viremic (category 3), as judged by absence of GSA and p27, developed increased antibody titers to FeLV and FOCMA. Seven cats were never viremic, as judged by the GSA in the peripheral blood leukocytes, but still had detectable serum p27 (category 4). Most category 4 cats developed high antibody titers against FOCMA and/or FeLV. Of 307 field cats examined, 7% of the healthy cats and 10% of the sick cats could be assigned to category 4. However, this difference was not significant (P greater than or equal to 0.05). Of 26 cats with neoplasms 2 (1 of 12 with lymphosarcoma) could be classified as category 4. Because virus could be isolated from 2 category 4 cats, they were considered immune carriers.  相似文献   

13.
Objective To determine prevalences of feline leukaemia virus (FeLV) and feline immunodeficiency virus (FIV) infections in ‘healthy’ cats that, through acute misadventure or other circumstance, were presented to veterinary practitioners. Prevalences of FeLV and FIV in this population were compared to those in a population of predominantly sick cats. Design and procedures Serum specimens were obtained over a 2-year period from 200 cats oldeer than 1 year of age presented to veterinary clinics for routine procedures, including cat fight injuries or abscesses, vehicular trauma, neutering, dental scaling, vaccination, grooming or boarding. An additional 894 sera were obtained over approximately the same period from specimens submitted by veterinarians to a private clinical pathology laboratory, mainly from sick cats suspected of having immune dysfunction, but including some sera from healthy cats being screened prior to FeLV vaccination. FIV antibody and FeLV antigen were detected in samples using commercial enzyme immunoassays. Results Amongst 200 ‘healthy’ cats, the prevalence of FeLV infection was 0 to 2%, and the prevalence of FIV was 6.5 to 7.5%, depending on the stringency of the criteria used to define positivity. FIV infection was significantly more prevalent in cats which resided in an inner city environment (P = 0.013). Of the 894 serum specimens submitted to the laboratory by practitioners, 11/761 (1.4%) were FeLV positive, while 148/711 (20.8%) were FIV positive. The prevalence of FIV was significantly higher in these predominantly ‘sick’ cats than in cats seen for routine veterinary procedures (P < 0.00001), while there was no difference in the prevalence of FeLV (P = 0.75) Conclusions The prevalence of FeLV and FIV in healthy cats may have been substantially overestimated in some previous Australian surveys. FeLV infection would appear to be a rare cause of disease in Australian cats. The higher prevalence of FIV positivity in sick as opposed to healthy cats infers that FIV infection contributes to the development of disease.  相似文献   

14.
FeLV was discovered 40 years ago and vaccines have been commercially available for almost two decades. So far, most FeLV pathogenesis and vaccine studies were conducted assaying parameters, such as virus isolation and antigen detection. Accordingly, regressive infection was characterized by transient or undetectable viremia, while persistent viremia is typically observed in cats with progressive infection. Using real-time polymerase chain reaction assays, the spectrum of host response categories to FeLV infection was recently refined by investigating proviral and plasma viral RNA loads. Cats believed to be immune to FeLV infection were found to turn provirus-positive after virus exposure. Moreover, efficacious FeLV vaccines were found unable to prevent provirus-integration and minimal viral replication. Remarkably, no difference was found in initial proviral and plasma viral RNA loads between cats with different infection outcomes. Only subsequently, the infection outcome is associated with FeLV loads. FeLV provirus was found to persist for years; reoccurrence of viremia and disease development was observed in some cats. Thus, aviremic provirus-positive cats are FeLV carriers and, following reactivation, may act as an infection source. However, integrated viral DNA may also be essential for solid protection and long-lasting maintenance of protective immunity. In conclusion, real-time TaqMan PCR and RT-PCR assays are highly sensitive and specific. They yield a more sensitive measure for FeLV exposure than antigen detection, virus isolation or immunofluoresence assays. We recommend the use of real-time PCR assays to identify FeLV exposed cats, particularly in catteries, and investigate obscure clinical cases that may be FeLV-associated. The use of sensitive molecular methods will contribute to a more in-depth understanding of the FeLV pathogenesis.  相似文献   

15.
Molecular techniques have demonstrated that cats may harbour feline leukaemia virus (FeLV) provirus in the absence of antigenaemia. Using quantitative real-time polymerase chain reaction (qPCR), p27 enzyme-linked immunosorbent assay (ELISA), anti-feline oncornavirus-associated cell-membrane-antigen (FOCMA) antibody testing and virus isolation (VI) we investigated three groups of cats. Among cats with cytopenias or lymphoma, 2/75 were transiently positive for provirus and anti-FOCMA antibodies were the only evidence of exposure in another. In 169 young, healthy cats, all tests were negative. In contrast, 3/4 cats from a closed household where FeLV was confirmed by isolation, had evidence of infection. Our results support a role for factors other than FeLV in the pathogenesis of cytopenias and lymphoma. There was no evidence of exposure in young cats. In regions of low prevalence, where the positive predictive value of antigen testing is low, qPCR may assist with diagnosis.  相似文献   

16.
A blind randomized field trial of a commercial FeLV vaccine was conducted. Cats on study were vaccinated with either a commercial FeLV vaccine or a placebo, then housed with FeLV-positive cats in a ratio of approximately 2 study cats to 1 infected cat (results of the first 12 months of the study have been reported). All surviving placebo-treated and FeLV-vaccinated cats were re-vaccinated 1 year after initial exposure to FeLV-infected cats. Exposure continued for an additional 12 months, and the viremia status of the cats was monitored by immunofluorescent antibody (IFA) and ELISA testing at 4-month intervals. During the second year of observation, 1 additional FeLV-vaccinated cat had positive results of 2 consecutive ELISA tests, but remained IFA negative. Classifying this cat as persistently viremic reduced the estimate of the preventable fraction, but did not alter the conclusions drawn earlier, viz, that vaccination appreciably reduces the number of cats that become persistently viremic after long-term natural exposure.  相似文献   

17.
In felids, feline leukemia virus (FeLV) infection results in a variety of outcomes that range from abortive (virus readily eliminated and never detectable) to progressive infection (persistent viremia and viral shedding). Recently, a novel outcome was postulated for low FeLV infectious doses. Naïve cats exposed to faeces of persistently infected cats seroconverted, indicating infection, but remained negative for provirus and p27 antigen in blood. FeLV provirus was found in some tissues but not in the bone marrow, infection of which is usually considered a necessary stage for disease progression. To investigate the impact of low FeLV doses on young cats and to test the hypothesis that low dose exposure may lead to an unknown pathogenesis of infection without involvement of the bone marrow, 21 cats were infected oronasally with variable viral doses. Blood p27, proviral and viral loads were followed until week 20 post-infection. Tissue proviral loads were determined as well. The immune response was monitored by measuring FeLV whole virus and p45 antibodies; and feline oncornavirus-associated cell membrane antigen (FOCMA) assay. One cat showed regressive infection (transient antigenemia, persistent provirus-positivity, and seroconversion) with provirus only found in some organs at sacrifice. In 7 of the 20 remaining cats FOCMA assay positivity was the only sign of infection, while all other tests were negative. Overall, the results show that FeLV low dose exposure can result in seroconversion during a presumed abortive infection. Therefore, commonly used detection methods do not detect all FeLV-infected animals, possibly leading to an underestimation of the prevalence of infection.  相似文献   

18.
A procedure for measuring in vitro feline neutrophil chemotaxis was developed, using a modified Boyden chamber apparatus and 3-microns-pore polycarbonate filters. A pooled feline serum sample was used as the chemoattractant. Chemotaxis was evaluated in 5 groups of cats: group 1-specific-pathogen-free cats that had not been exposed to feline leukemia virus (FeLV); group 2-previremic, FeLV-infected, specific-pathogen-free cats; group 3-FeLV-viremic, subclinically affected cats; group 4-FeLV-viremic, clinically affected cats; and group 5-sick cats that were not infected with FeLV. Neutrophils from the viremic, clinically affected cats had significantly lower (P less than 0.025) chemotactic responses than did those from subclinically affected, viremic cats. Conversely, neutrophils from cats that were ill due to causes other than FeLV had the highest mean chemotactic values. Among the viremic, subclinically affected cats, a linear relationship was found between age and chemotaxis, indicating that impairment of neutrophil function may be greater in younger viremic cats. However, FeLV-infected cats can not be identified on the basis of neutrophil chemotaxis.  相似文献   

19.
A new recombinant gp70 vaccine was found to be safe and effective for prevention of infection by FeLV. The vaccine incorporates a unique purified saponin adjuvant with the recombinant antigen. Serious systemic reactions were not observed during the efficacy trial. Local reactions were transient and mild. More than 2,000 doses were administered to a cross section of household cats in a field safety trial. Only 1 cat had hypersensitivity reaction, which resolved. Among veterinarians who used the vaccine and the cat owners, the vaccine was judged satisfactory and safe. After rigorous intraperitoneal challenge exposure without use of immunosuppressants, 100% of the controls in the efficacy trial became infected, 70% of which remained persistently infected with FeLV. Among vaccinates, 45% were never viremic and 40% cleared transient infection within 12 weeks after challenge exposure. Of the 20 vaccinated cats, 3 were persistently infected. Overall, 85% of cats vaccinated with this recombinant DNA FeLV vaccine resisted persistent FeLV infection after stringent challenge exposure, which translates to preventable fraction of 78.6%.  相似文献   

20.
Background: Nonregenerative cytopenias such as nonregenerative anemia, neutropenia, and thrombocytopenia in cats with feline leukemia virus (FeLV) antigen are assumed to be caused by the underlying FeLV infection. In addition, cats with negative FeLV antigen-test results that have cytopenias of unknown etiology often are suspected to suffer from latent FeLV infection that is responsible for the nonregenerative cytopenias.
Objective: The purpose of this study was to assess the role of latent FeLV infection by polymerase chain reaction (PCR) in bone marrow of cats with nonregenerative cytopenias that had negative FeLV antigen test results in blood.
Animals: Thirty-seven cats were included in the patient group. Inclusion criteria were (1) nonregenerative cytopenia of unknown origin and (2) negative FeLV antigen test result. Antigenemia was determined by detection of free FeLV p27 antigen by ELISA in serum. Furthermore, 7 cats with positive antigen test results with nonregenerative cytopenia were included as control group I, and 30 cats with negative antigen test results without nonregenerative cytopenia were included as control group II.
Methods: Whole blood and bone marrow samples were tested by 2 different PCR assays detecting sequences of the envelope or long terminal repeat genes. FeLV immunohistochemistry was performed in bone marrow samples.
Results: Two of the 37 cats (5.4%) in the patient group were positive on the bone marrow PCR results and thus were latently infected with FeLV.
Conclusions and Clinical Importance: The findings of this study suggest that FeLV latency is rare in cats with nonregenerative cytopenias.  相似文献   

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