Analysis of bone marrow response before and during treatment with AZT (3'-azido-3'-deoxythymidine) of cats (Felis catus) naturally infected with feline immunodeficiency virus

• Grant number: 05/04323-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: January 01, 2006
• End date: December 31, 2006
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Clinics and Surgery
• Principal Investigator: Regina Kiomi Takahira
• Grantee: Luis Fernando Negro Silva
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

The feline imunnodeficiency is one of the most prevalent infectious diseases in cats. A survey with 401 animals reported 11,7% of positivity. Studies on peripheral blood, bone marrow and the changes in the hematopoietic precursors can reveal the mielossupression mechanisms and the induction of diseases associated to the infection by the retrovirus in animals and humans. It was demonstrated that bone marrow cells are reservoirs for FIV and a site for its replication and that therapies associating nucleotides analogues (AZT and 3TC) and non analogues (ABC) suppress the viral replication by synergism, but they also possess a high degree of medullar toxicity. The present work has for objectives: to evaluate the bone marrow of naturally infected cats, the answer of the bone marrow of the animals submitted to the treatment in two moments: two months after the beginning of this, and at the end of the four months of treatment and also to evaluate the possible medullar toxicity induced by the treatment. Naturally infected domestic cats (Felis catus) from the region of Botucatu-SP, FIV positive by PCR will be separated in two groups of five animals: treated and non treated (control). The treatment and viral quantification will be part of project “Evaluation of the treatment with AZT (3’-azido-3’-deoximitidine) in cats naturally infected by CLADE B feline immunodefiency virus and characterization of mutant resistant” (process nº05/53.786-5). The animals will be treated with AZT pediatric solution in the dose of 5 mg/kg every 12 hours for four months. The bone marrow will be collected immediately before the treatment, two months after its beginning and at the end of the four months of treatment. Bone marrow will be collected with a special bone marrow aspirative biopsy needle, through a puncture in the feline iliac crest. The animals will be anesthetized before the beginning of the collection, and then they will be placed in the collection position. After the local antisepsis, the needle will be positioned on the iliac crest. After the fixation of the needle in the medullar cavity, the stilet will be removed and a 20 mL plastic disposable syringe will be connected, and it will be applied a negative pressure for the aspiration of the medullar material. A maximum volume of 0,5 mL of bone marrow will be aspired in EDTA at 3% diluted in physiologic saline, and them the sample will be homogenized. The smears of bone marrow will be made immediately after the collection and air dried for posterior staining and reading. The slides will be analyzed in an optical microscope, analyzing four parameters: cellurarity estimation in a low magnification field, visualization of the morphology and maturation of the hematopoietic cellular lineages; differential cell count in 500 cells in 100X field and estimation of the mieloid:eritroid ratio. The findings will be compared and analyzed in agreement with Harvey, 2003. The differences among the groups will be compared by the variance analysis (ANOVA) or by the Kruskal-Wallis test, for variables with parametric and not parametric distribution, respectively. There will be considered significant the differences smaller than 0,05 (p).