Photosensitive chemical and laser light treatments decrease epizootic hemorrhagic disease virus associated with in vitro produced bovine embryos

Photoinactivation was employed to eliminate EHDV-2 from in vitro produced bovine embryos experimentally exposed to this virus. Immature oocytes were matured, fertilized, and cultured in chemically defined conditions. All treatments were performed on zygotes. Developmental potential of zygotes and cell numbers of resulting hatched blastocysts were assessed after exposure to a 1 mW helium neon laser (633 nm, red) for 1, 5, 10, and 15 min; the photosensitive chemicals hematoporphyrin (15 microM) and hypericin (1 and 10 microM) for 15 min; a combination of 10 microM hypericin and laser light for 1, 3, or 5 min; and a combination of 15 microM hematoporphyrin and laser light for 1, 2, or 3 min. There were no significant differences among proportions of embryos developing or cell numbers after treatment with or without exposure to laser light alone for up to 10 min. No differences were observed after exposure of zygotes to photosensitive chemicals alone. Exposure to 10 microM hypericin and 5 min of laser light or 15 microM hematoporphyrin and 2 min of laser light compromised zygote developmental potential. After exposure to 10(6) TCID50/mL EHDV-2 for 90 min groups of 10 zygotes were exposed to 10 microM hypericin or 15 microM hematoporphyrin and laser light to inactivate the virus. Hematoporphyrin was effective with 3 min light exposure at reducing the percentage of EHDV-2 contaminated zygote pools (16.7%) as compared to EHDV-2 exposed pools without treatment (88.9%) but hematoporphyrin + 1 min light was ineffective. Hypericin + 3 min light provided an intermediate effect (55.6%).