D. L. Pavão

Acceptable microorganisms concentration in a semen sample for in vitro embryo production

The aim of this study was to report that the acceptable concentration of microorganisms in a semen sample for insemination may not be safe for an in vitro fertilization procedure. It seems that the semen sample should be completely germ-free, because of the excellent microorganism proliferation condition promoted by the in vitro environment.

Evaluation of the effectiveness of semen processing techniques to remove bovine viral diarrhea virus from experimentally contaminated semen samples

The aim of this study was to evaluate the capacity of three semen processing techniques, Percoll gradient centrifugation, Swim-up and a combination of Swim-up and Percoll gradient centrifugation, to reduce the viral load of bovine viral diarrhea virus (BVDV) in experimentally infected semen samples. The evaluation was performed using two approaches: first, searching for the presence of virus in the processed samples (via virus titration and RT-PCR) and second, ascertaining the possible interference on in vitro embryo production. The sperm count and DNA integrity (Comet assay) of the processed samples were analyzed (Experiment 1). The amount of virus in the processed samples was determined by titration in cell culture (Experiment 2). The samples processed by Swim up/Percoll gradient centrifugation were utilized for in vitro embryo production, and the embryos produced were tested for BVDV by RT-PCR (Experiment 3). Sperm concentration, Comet assay and embryo production were analyzed by chi-squared tests (P<0.05). There was a significant difference between sperm separation techniques when the sperm count and Comet assay were analyzed. The sperm count obtained from the Swim up/Percoll gradient centrifugation group was lower than that obtained in either of the two other groups (Swim up and Percoll gradient centrifugation), and the Comet assay showed that the combination of the two semen processing techniques (Swim up/Percoll gradient) produced a 1.1% prevalence of Comet level 2, which was not observed in the other groups. The BVDV titer (10(6.68)TCID(50)/mL) added to experimentally infected semen samples decreased after Percoll gradient centrifugation to 10(2.3)-10(1)TCID(50)/mL; for the Swim up group, the titer range was 10(3.3)-10(1.87)TCID(50)/mL, and in the Swim up/Percoll gradient centrifugation group, BVDV was undetectable. The decreases in titer varied from 99.9% in the Swim up-processed group to 100% in the Swim up/Percoll gradient centrifugation group. In vitro embryo production displayed similar blastocyst development rates among all groups, and RT-PCR was negative for the produced embryos. The data showed that the combination of Swim up/Percoll gradient centrifugation promoted the elimination of BVDV from the semen samples without damaging spermatozoa cells and also allowed successful in vitro embryo production free of BVDV. Hence, the risk of BVDV contamination is negligible for the embryo recipient.

Interação do Mycoplasma bovigenitalium com células do cumulus in vitro após o período de maturação oocitária bovina

The Mycoplasma is considered cosmopolitan and can be disseminated through international trade of animals, industrialized semen and embryo transfer products. The expansion of cumulus cells is used as a parameter for evaluating cattle oocytes cultivated in vitro, and their morphological changes are representative. The aim of the present study was to evaluate the interaction of Mycoplasma bovigenitalium with primary-culture cumulus cells, after the in vitro maturation period. Cumulus complex oocytes (COCs) obtained through follicular puncture of ovaries from a cattle slaughterhouse were divided into two groups to be matured for 24 hours in the maturation medium (TCM 199 + hormones) in a climate controlled chamber at 38o C, 5% CO2, and 95% humidity. Subsequently, the oocytes were removed from the plates, which remained with only the cumulus cells attached. With the monostratum cell formed, one group was infected with 30 oL (5 x 106 cells/mL) M. bovigenitalium, replicated in modified Hayflick medium at 37o C in a mycroaerofilic chamber, while the other was kept as a control. The results showed that with 24 hours of exposure to the pathogen, the cultures showed a small number of rounded and grainy cells, when compared to the controls. This effect persisted until the 7th day, when a process of cell detachment began. It can be concluded that a mycoplasma contamination may be imperceptible to the manipulations of FIV, because cells infected by this group of bacteria present no cloudiness in the culture field, and when they do not lyse the host cell, they make it more susceptible to environment and other infectious agents.

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

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.

274 ASSESSMENT OF TRYPSIN AND ANTIBIOTIC TREATMENT EFFECTIVENESS IN IN VITRO-MATURED OOCYTES EXPERIMENTALLY EXPOSED TO LEPTOSPIRA INTERROGANS SEROVAR GRIPPOTYPHOSA

Techniques of production and transfer of embryos is safe as long as it follows the control regulations defined by the manual of the International Embryo Transfer Society (IETS) for treating oocytes with trypsin, antibiotics, and TCM-199 medium. The aim of this work was to evaluate the effectiveness of treatments, established by IETS, in bovine oocytes experimentally exposed to Leptospira interrogans serovar Grippotyphosa and to assist implementation of quality control standards on in vitro embryo production. The oocytes were obtained through follicular puncture of ovaries derived from the slaughterhouse. They were selected and divided into 4 groups: the control group and groups exposed to 5, 10, and 30 μL of an L. interrogans strain at 4.7 × 105 μL-1; and 4 additional groups exposed to the same concentrations of another L. interrogans strain at 6.3 × 105 μL-1, in which the gene for virulence is not expressed. The groups were kept in maturation medium (TCM-199 medium, 0.5 (iLof FSH, 50IU mL-1 hCG, 1μL mL-1 17-βiestradiol) and incubated at 38°C, 5% CO2, and 95% humidity for 24 h. All the groups were separately subjected to the treatments with antibiotic, trypsin, and TCM-199 medium after maturation. The treatment involved 10 drops (each 200 μL), with 8 drops of TCM-199 medium and 2 drops of antibiotic (penicillin 10000 IU mL-1 and streptomycin 10 mg mL-1) or trypsin 0.25%; exposed to trypsin and antibiotic for 120 s. For the sequential washes, all drops contained TCM-199 medium. The analysis for presence of the pathogen by dark-field optical microscopy showed that in the groups exposed to L. interrogans and subjected to antibiotic washes, the effectiveness was 50% (100/200) for the group exposed to 5 μL, 40% (80/200) for that exposed to 10 μL, and 22.5% (45/200) for that exposed to 30 μL. We found the same results after the trypsin washes. After the washings with TCM-199 medium, the groups infected with 5 and 10 μL presented 100% of effectiveness; however, for the group infected with 30 μL, the washings were not effective. For the groups exposed to L. interrogans that did not express virulence, after the washings with antibiotics as well as with trypsin, the results showed no effectiveness in all of them (n = 200). Yet, after washings with TCM-199, the group exposed to 5 μL showed 28.5% (57/200) of effectiveness, whereas in those exposed to 10 and 30 μL, the medium washes were not effective. Complementary studies are being made with ultramicrotome cut and polymerase chain reaction for more reliable conclusions, to confirm the results. With such results, we conclude that the quality control regulations established by IETS for IVP could be reviewed and possibly redefined, because the effectiveness of the treatment may depend not only on the pathogen species, but also its virulence as well as its concentration and the action of the treatments on the type of pathogen. We thank Vitrocel/Embriolife for supporting the laboratory.