2015 ACVIM Forum Research Abstract Program

Vaccination against FIV with this product induces antibodies that are detected transiently by the commercially available kit. This assay cannot be used alone to accurately distinguish a cat with naturally occurring FIV infection from a cat that has been vaccinated against FIV. In an attempt to understand the immune response of cats infected by Leishmania infantum chagasi, the aim of this study was to evaluate the level of expression of genes encoding interleukins IL-4, IL-10, IL-12p40 and IFN-c in spleen samples of naturally infected cats, by quantitative reverse transcription PCR (qRT-PCR). Disease diagnosis was based on the finding of amastigote forms of the parasite by cytological examination and confirmed by DNA amplification of L. infantum chagasi in bone marrow tissue. Three groups of cats were evaluated; the first group composed by six symptomatic naturally infected cats, the second composed by six asymptomatic naturally infected cats and the third composed of six clinically healthy and uninfected cats. Prior to cats inclusion in the study owners were informed of the necessary interventions and their consent was obtained for each cat. The study was approved by the Committee for Ethics in Animal Research, of São Paulo State University. Total RNA was extracted from spleen and converted into cDNA. Cytokines gene expression was measured and final quantitation was evaluated by 2 -DDC T method. An endogenous "housekeeping" gene (beta-actin) was quantified and used to normalize the results. The mRNA expression of IL-4 was reduced in both groups in comparison to healthy cats, with gene expression of symptomatic and asymptomatic cats supressed 2.52 and 2.22 times, respectively. The mRNA expression of IL-10 gene was reduced in all naturally infected cats. The reduction was slightly higher in symptomatic (supressed 2.40 times) than in asymptomatic (supressed 2.15 times) cats when compared to the control group. The mRNA expression of IL-12 was reduced in both groups in comparison to healthy cats, with gene expression of asymptomatic and symptomatic cats supressed 2.52 and 2.30 times, respectively, in comparison to healthy cats. The mRNA expression of IFN-c gene was reduced in all naturally infected cats, regardless of the presence or absence of symptoms, when compared to the control group. The reduction was more significant in asymptomatic (supressed 1.15 times) than in symptomatic (supressed 0.57 times) cats. The results of this study suggest that there is reduced expression, and eventually production, of the four cytokines in the spleen of cats naturally infected by L. infantum chagasi, regardless of the clinical status of animals, and that spleen cells of the studied cats did not to elicit a specific immune response to Leishmania infection.