An RNA-Directed Gene Editing Strategy for Attenuating the Infectious Potential of Feline Immunodeficiency Virus-Infected Cells: A Proof of Concept.

Modern antiretroviral therapy for immunodeficiency viruses, although remarkably effective in controlling viral transcription, and overt virus-associated morbidity, has failed to absolutely eradicate retroviruses from their infected hosts as a result of proviral integration in long-lived reservoir cells. Immunodeficiency virus-infected patients are therefore consigned to lifelong antiviral therapy as a means to control viremia, viral transmission, and infection-associated morbidity. Unfortunately, lifelong antiviral therapies can be difficult for patients to continuously maintain and may be associated with therapy-specific morbidities. Patient advocates have argued for new methods to achieve retroviral eradication. As a proof-of-concept study, a lentivirus-delivered RNA-directed gene editing strategy was utilized in a series of in vitro experiments in an attempt to attenuate the feline immunodeficiency virus (FIV) proviral load, viral transcription, and production of infectious virions. We found that a feline T lymphocyte cell line (MCH5-4) treated with an FIV-specific clustered regularly interspersed short palindromic repeats (CRISPR)-associated protein 9 (Cas9) gene editing tool resulted in a reduction of cell-free viral RNA relative to control cells. Decreased infectious potential was demonstrated in a two-step FIV infection study-naïve MCH5-4 cells infected with cell-free FIV harvested from FIV-infected and CRISPR lentivirus-treated cells had less integrated proviral DNA than control cells. This study represents the initial steps towards the development of an effective method of proviral eradication in an immunodeficiency virus-infected host.

Assessment of feline blood for transfusion purposes in the Dublin area of Ireland.

The prevalence of A, B and AB blood types and of feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) infection was determined in cats in Ireland, in order to determine risk factors for blood taken for transfusion purposes. EDTA blood samples were available from 137 non-pedigree cats and 39 pedigree cats (91 females and 85 males, aged four months to 15.0 years) in the Dublin area of Ireland. Of the 176 EDTA blood samples obtained, 112 (from 92 healthy cats and 20 sick cats) were tested for the presence of both FIV antibodies and FeLV antigens. Blood typing was performed using an immunochromatographic cartridge (CHROM; Alvedia). Testing for FIV and FeLV was performed by ELISA (SNAP FIV/FeLV Combo Test; Idexx Laboratories). Of the 39 pedigree cats, the majority (38 [97.4 per cent]) was type A, and only one (2.6 per cent) was type B. Of the 137 non-pedigree cats, the majority (116 [84.7 per cent]) was type A, 20 (14.6 per cent) were type B, and one (0.7 per cent) was type AB. Of the 92 healthy cats tested, the prevalence of FIV and FeLV positivity was 4.35 and 1.09 per cent, respectively. None of the 20 sick cats tested was FIV-positive; two (10 per cent) of the 20 sick cats were FeLV-positive.

Feline immunodeficiency. ABCD guidelines on prevention and management.

OVERVIEW: Feline immunodeficiency virus (FIV) is a retrovirus closely related to human immunodeficiency virus. Most felids are susceptible to FIV, but humans are not. Feline immunodeficiency virus is endemic in domestic cat populations worldwide. The virus loses infectivity quickly outside the host and is susceptible to all disinfectants. INFECTION: Feline immunodeficiency virus is transmitted via bites. The risk of transmission is low in households with socially well-adapted cats. Transmission from mother to kittens may occur, especially if the queen is undergoing an acute infection. Cats with FIV are persistently infected in spite of their ability to mount antibody and cell-mediated immune responses. DISEASE SIGNS: Infected cats generally remain free of clinical signs for several years, and some cats never develop disease, depending on the infecting isolate. Most clinical signs are the consequence of immunodeficiency and secondary infection. Typical manifestations are chronic gingivostomatitis, chronic rhinitis, lymphadenopathy, weight loss and immune-mediated glomerulonephritis. DIAGNOSIS: Positive in-practice ELISA results obtained in a low-prevalence or low-risk population should always be confirmed by a laboratory. Western blot is the 'gold standard' laboratory test for FIV serology. PCR-based assays vary in performance. DISEASE MANAGEMENT: Cats should never be euthanased solely on the basis of an FIV-positive test result. Cats infected with FIV may live as long as uninfected cats, with appropriate management. Asymptomatic FIV-infected cats should be neutered to avoid fighting and virus transmission. Infected cats should receive regular veterinary health checks. They can be housed in the same ward as other patients, but should be kept in individual cages. VACCINATION RECOMMENDATIONS: At present, there is no FIV vaccine commercially available in Europe. Potential benefits and risks of vaccinating FIV-infected cats should be assessed on an individual cat basis. Needles and surgical instruments used on FIV-positive cats may transmit the virus to other cats, so strict hygiene is essential.

2008 American Association of Feline Practitioners' feline retrovirus management guidelines.

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.

Immunotherapy with internally inactivated virus loaded dendritic cells boosts cellular immunity but does not affect feline immunodeficiency virus infection course.

Immunotherapy of feline immunodeficiency virus (FIV)-infected cats with monocyte-derived dendritic cells (MDCs) loaded with aldrithiol-2 (AT2)-inactivated homologous FIV was performed. Although FIV-specific lymphoproliferative responses were markedly increased, viral loads and CD4+ T cell depletion were unaffected, thus indicating that boosting antiviral cell-mediated immunity may not suffice to modify infection course appreciably.

Feline leukemia virus and feline immunodeficiency virus.

Ophthalmic manifestations of FeLV or FIV infection can occur in all ocular tissues and may be manifestations of direct viral effects or secondary to viral-related malignant transformation. Additionally, the manifestations of common feline ophthalmic pathogens may be more severe and poorly responsive to therapy because of the immunosuppressive effects of FeLV or FIV infection. Prompt diagnosis of underlying viral infection in cats with ophthalmic disease is paramount for accurate diagnosis and prognosis and is required for appropriate therapeutic decision making.

Feline bone marrow transplantation: its use in FIV-infected cats.

The use of autologous and allogenic bone marrow transplantations (BMT) in FIV-infected and uninfected cats is a novel therapy for feline hematopoietic diseases and retroviral infections. A total of 13 specific pathogen-free (SPF) cats received either autologous or allogenic BMT and seven of these cats were also infected with FIV before autologous or allogenic BMT. All BMT recipients received total body irradiation of 900 cGy just before BMT. Two FIV-infected and four uninfected cats received autologous uninfected BM cells cryopreserved before BMT. Five infected and two uninfected cats received BM cells from allogenic uninfected donors (RBC-, MHC-, and cross-matched). MHC-matching was based on mixed leucocyte reaction (MLR) and the donor-recipient combination which was compatible by MLR analysis, was used in this study. Recipients were monitored for hematology, immunology, virology, and clinical signs. All FIV-infected and uninfected recipients of autologous BMT had complete engraftment with minimal complications. Uninfected recipients of allogenic BMT had a more severe clinical episode with slower rate of engraftment. None of these BMT groups had mortality. In contrast, only two of the five infected recipients of allogenic BMT survived for a significant period of time (23 and 50 weeks) and rest of the cats succumbed to transfusion reactions. Both infected BMT groups had persistent CD4/CD8 inversion, low CD4+ cell counts, and FIV infection of engrafted peripheral blood mononuclear cells (PBMC). Overall, successful autologous and allogenic BMTs were performed in FIV-free cats. All infected recipients of autologous BMT had compete engraftment and are currently alive, with thelongest survival time being over 1 year. Thus, BMT in combination with antiviral drug therapies may be an alternative therapy against retroviral infection.

Feline immunodeficiency virus infection: an overview.

In 1987, Pedersen et al. (1987) reported the isolation of a T-lymphotropic virus possessing the characteristics of a lentivirus from pet cats in Davis, California. From the first report onwards, it was evident that in causing an acquired immunodeficiency syndrome in cats, the virus was of substantial veterinary importance. It shares many physical and biochemical properties with human immunodeficiency virus (HIV), and was therefore named feline immunodeficiency virus (FIV). This article reviews recent knowledge of the aetiology, epidemiology, pathogenesis, clinical signs, diagnosis, prevention, and treatment options of FIV infection.

Caring for the retrovirus infected cat.

No commercial vaccine [correction of vacine] exists for feline immunodeficiency virus (FIV), and although feline leukemia virus (FeLV) vaccines are available, they are neither 100% effective nor used in all cats. These realities clearly indicate the veterinarian will be required to treat either FeLV- or FIV-positive cats for some time to come. The management of FIV- or FeLV-positive cats may require supportive therapies as well as virus-specific therapies such as zidovudine (AZT; Retrovir, Burroughs Wellcome, Research Triangle Park, NC).

Opportunistic infections associated with retroviral infections in cats.

Naturally occurring infection of cats with feline leukemia virus and feline immunodeficiency virus is common. A wide variety of clinical manifestations occur in retrovirus-infected cats including gastrointestinal tract disease, respiratory tract disease, central nervous system disease, ophthalmic disease, hepatic disease, urogenital tract disease, dermatologic disease, hematologic disease, and musculoskeletal disease. Clinical signs are often directly attributable to the primary viral infection, but because both feline leukemia virus and feline immunodeficiency virus can induce immunodeficiency, opportunistic secondary infections may cause the clinical manifestations of disease in some cats. Diagnosis, treatment, and zoonotic potential of the common opportunistic agents associated with feline retroviral infections are reviewed.

Problemas en el manejo de pacientes con SIDA / Problems in the management of AIDS patients

Para conocer los patrones clínico-epidemiológicos en el Atlántico, estudiamos 138 pacientes infectados con el VIH en dos instituciones de salud y la consulta privada; esta patología se diagnosticó mayormente en hombres que en mujeres (relación 3:1). El grupo de edad más afectado correspondió a las edades de 26 a 35 años. La conducta de riesgo más importante fue la promiscuidad. La población afectada de herosexuales es similar a la de homosexuales. La alta mortalidad, 75 por ciento de los casos en seis años de seguimiento, esta relacionada con el diagnóstico en una etapa avanzada (57,2 por ciento) y las infecciones oportunistas. El VIH, en nuestro medio, tiene un patrón epidemiológico tipo II. El número de casos infectados está en ascenso, confirmándose el desarrollo de la epidemia. El manejo ambulatorio y hospitalario de la enfermedad muestra un gran número de defectos, proponiéndose la ejecución de un plan conjunto con las instituciones de salud

Reversal of feline leukemia virus infection by adoptive transfer of lectin/interleukin-2-activated lymphocytes, interferon-alpha, and zidovudine.

Previous experimental studies utilizing human recombinant interferon-alpha-2b (IFN alpha-2b) alone or with zidovudine (AZT) to treat established feline leukemia virus (FeLV) infection resulted in a significant reduction in circulating virus throughout a 49-day treatment period. However, the anti-FeLV effect of IFN alpha was limited by the production of IFN alpha-neutralizing antibodies detected 7 weeks after the start of treatment. AZT without IFN alpha had no effect on circulating virus load. To examine the hypothesis that combination chemoimmunotherapy might induce the clearance of FeLV infection, persistently infected cats were infused with activated lymphocytes, IFN alpha, and AZT 12 weeks after infection with FeLV. Recipient cats received weekly infusions of 1.46 x 10(8) lymphocytes activated in vitro with lectin/IL-2 comprised of 98% T cells and an even distribution of CD4+ and CD8+ lymphocytes. FeLV infection was cleared in 4 of 9 cats receiving combined therapy after four adoptive cell transfers. These cats remained negative for circulating virus during a 63-day treatment period (17 adoptive cell transfers) despite the production of anti-IFN alpha-neutralizing antibodies. Sequential development of virus-neutralizing and virus envelope antibody titers were detected in those cats which cleared retroviremia, an antiviral response that was absent in untreated control animals or nonresponders. Three of four responder cats remained negative for FeLV 95 days after treatment was discontinued. Treatment of cats with lymphocytes without chemotherapy failed to influence the course of FeLV infection. These results suggest that combined treatment using IFN alpha and adoptive lymphocyte transfer served to reconstitute antiviral humoral immunity, counteract immunosuppression, and induce the reversal of retroviremia.

Husbandry practices for cats infected with feline leukemia virus or feline immunodeficiency virus.

Cats that are persistently infected with FeLV or feline immunodeficiency virus but are not manifesting clinical signs of disease are at risk for developing a wide variety of immunosuppressive, degenerative, or neoplastic diseases. Infected cats should be isolated to prevent transmission of virus to healthy cats, and to protect infected cats from exposure to pathogens that can cause life-threatening secondary infections. Iatrogenic transmission of virus from infected cats in isolation to healthy cats may be reduced by strict adherence to handling, sanitation, and disinfection procedures. Husbandry practices that may delay the complications of infection include regular vaccination, provision of high-quality diets, reduction of stress, control of endoparasites and ectoparasites, and early and aggressive treatment of clinical signs of disease.