297 ASSESSMENT OF THE TRANSPORTATION OF BOVINE OOCYTES EXPERIMENTALLY EXPOSED TO BOVINE HERPESVIRUS TYPE 1 (BoHV-1) DURING THE PERIOD OF MATURATION IN IN VITRO OVIDUCTS

Abstract

The necessity of greater elucidation about oocyte pathogen interactions made us examine the interaction of bovine herpesvirus type 1 (BoHV-1), Los Angeles strain, with oocytes matured in vitro to assess the potential hazard of transmission of such infectious agent through IVF. The process of capacitation and transportation of oocytes through the oviduct depends on the quality of the female gamete. Keeping in mind that the BoHV-1 causes morphophysiological modification in oocytes, the aim of this study was to evaluate, in an experimental model of in vitro oviduct, whether the pathogen interferes in the transportation of oocytes. This was determined using the percentage of oocyte recovery and assessment of the alteration in the morphology of the oviduct lumen. Oviducts and oocytes were collected from bovine ovaries derived from slaughterhouse cows. The oviducts were dissected, washed, and placed in Petri dishes (100 × 20 mm). On the previous portions of the infundibulum, in vitro-matured control oocytes or oocytes exposed to the virus (105.5 TCID50 mL^-1) were introduced (20 oocytes per group) and then immersed in 100 mL of TCM-199 medium. Each dish was incubated at 38°C, 5% CO₂, and 95% humidity for 24 h. Then, we introduced in the infundibulum, through intramammary infusion probe, 5 mL from a physiologic solution containing 1% of bovine fetal serum. Each oviduct effluent was collected separately and evaluated through a stereoscope for the recovery and counting of oocytes. Immediately after the recovery, both oviduct groups were sectioned longitudinally and observed through an optical microscope (100 ×) for a morphological evaluation of the luminar area. For the control group, the percentage of recovery was 14.9% (65/437), whereas in the infected group, the oocyte recovery was 23.4% (100/428). The statistical analysis was made according to Student’s t-test (P < 0.05), and presented a significant difference in the final results. The previous results show that the group of oocytes that was exposed to the virus presented a higher percentage of recovery compared with the control group. The oviducts that received the exposed oocytes presented areas where it seemed there has been cytopathic effect represented by dark and lumpy sections, in which there were round and degenerating cells mainly located in the oviducts’ peripheral area. The morphophysiological modifications in contaminated oocytes and oviducts probably complicate their transportation and also interferes in the process of their liberation. It is relevant to elucidate the importance of the studies above because of their participation in the recovery of these gametic cells in bovine oviducts, as well as the transmission during IVF processes.

Vitrocel/Embriolife.