Comparison of T-cell subpopulations in cats naturally infected with feline leukaemia virus or feline immunodeficiency virus.

T-cell subsets were studied by flow cytometry in 58 feline leukaemia virus (FeLV)-positive cats with naturally acquired FeLV infection to determine whether the changes in CD4+ or CD8+ T cell populations differed from those observed in 55 feline immunodeficiency virus (FIV)-positive cats with naturally acquired FIV infection. The sole criterion for inclusion into the study was seropositivity. Mean (SD) CD4+ T cell values of FeLV positive cats were decreased to 31.1 (8.0) per cent and their CD8+ T cell values were increased to 22.8 (6.3) per cent in comparison with uninfected control cats (37.9 [9.5] per cent CD4+; 15.2 [6.3] per cent CD8+). The CD4+/CD8+ ratio was reduced to 1.5 (0.7), compared with 3.0 (1.5) in 39 FeLV-and FIV-negative control cats. Differences from control values were significant, but there was no significant difference between CD4+ and CD8+ lymphocytes of FeLV-versus FIV-infected cats. These findings indicate that FeLV and FIV have similar effects on T lymphocyte subsets. Both retrovirus infections can induce immunodeficiency, both viruses infect a broad range of lymphohaemopoietic cells, despite having different primary target cells, and can induce the killing of lymphocytic cells in vitro. It is concluded that a decreased CD4+/CD8+ ratio is not restricted to FIV infections but may also occur in FeLV infection.

Use of two virustatica (AZT, PMEA) in the treatment of FIV and of FeLV seropositive cats with clinical symptoms.

In the present study the therapeutic efficacy and the side effects of two antiretroviral compounds used in human acquired immunodeficiency syndrome (AIDS) research, 3'-azido-2',3'-dideoxythymidine (AZT, zidovudine, Retrovir) and 9-(2-phosphonylmethoxyethyl)adenine (PMEA), were investigated in the treatment of cats naturally infected with feline immunodeficiency virus (FIV) and cats naturally infected with feline leukemia virus (FeLV). AZT was administered subcutaneously at a dose of 5 mg kg-1 body weight every 12 h and PMEA was administered subcutaneously at a dose of 2.5 mg kg-1 body weight every 12 h during a 3 week hospitalization. The therapeutic efficacy of both compounds was investigated. There was a stronger potency of PMEA than of AZT on the regression of stomatitis in FIV and in FeLV infected cats. In addition, in FIV infection PMEA had a stronger effect on the improvement of the general clinical status. Both antiretroviral compounds were potent agents to improve the immunologic status of FIV infected cats by raising the CD4/CD8 ratio. In FeLV infection PMEA and AZT appeared to reduce antigenemia. The hematological side effects caused by PMEA were severe and stronger than those of AZT. Therefore the advantage of PMEA in clinical and immunologic improvement was diminished by the hematologic disorders, which do not allow long term treatment with this drug in the dose used.

Decline in CD4+ cell numbers in cats with naturally acquired feline immunodeficiency virus infection.

T-cell subsets were studied by fluorescence-activated cell sorter analysis in 57 feline immunodeficiency virus (FIV)-seropositive cats with naturally acquired FIV infection to see whether CD4(+)-CD8+ alterations were comparable to those observed in human immunodeficiency virus-infected patients. CD4+ values were decreased and CD8+ values were increased. The CD4+/CD8+ ratio was reduced to 1.6, compared with 3.3 in 33 FIV-seronegative control cats. Variance analysis of data showed a significant influence of FIV seropositivity, sex, and spaying of female cats on CD4+ values. CD8+ values were significantly influenced by FIV seropositivity, age, and breed. These findings indicate a similarity between FIV and human immunodeficiency virus infections, as far as alterations of T-cell subsets are concerned.