Ultrastructural alterations in some organelles of bovine embryos exposed to bovine herpesvirus-1 (BHV-1) in vitro

Abstract

The aim of this study was to evaluate the ultrastructure of early bovine embryos after the microinjection of bovine herpesvirus (BHV-1) viral suspension into the subzonal space and the possibility of virus penetration into the cellular structures of embryos. The embryos (morula, early blastocyst) were recovered from superovulated Holstein-Friesian donor cows on Day 6 of the estrous cycle. Part of embryos were microinjected with the suspension of BHV-1 under the ZP, washed in SOF-medium and cultured for 48 h. Embryo development was evaluated by morphological inspection, the presence of viral particles was determined both immunocytochemically (fluorescent anti-IBR-FITC conjugate) and by transmission electron microscopy (TEM) on the basis of ultrastructure of cellular organelles. It was found that BHV-1 microinjection impairs embryo development to higher preimplantation stages compared with the control. Immunofluorescent analysis confirmed the presence of BHV-1 particles in all BHV-1-microinjected embryos. TEM detected the presence of BHV-1 particles and showed ultrastructural alterations in cell organelles. Our study describes for the first time the presence of virus-like particles and changes occurred as a consequence of viral infection of embryos. Virus-like particles were revealed in vacuoles of disintegrated cytoplasm, around nuclei and inside them. We suppose that consequences of viral infection on the embryo viability may depend also on the titre of virus. Based on these observations we conclude that BHV-1 infection compromises preimplantation development of bovine embryos in vitro.