Members of the herpesvirus family, cytomegalovirus (CMV), Epstein-Barr virus (EBV), and herpes simplex virus (HSV), have been recognized as causal agents of chorioretinal inflammatory diseases. Reverse genetics experiments further demonstrated that a G(2254) A(2254) nucleotide mutation introduced in neurovirulent strain Ab4, which resulted in an asparagine for aspartic acid substitution (D(752) N(752)), rendered the virus nonneurovirulent in the equine. Upon infection, the linear viral DNA is delivered to the nucleus, where it circularizes to form the viral episome. Initiation of viral DNA replication caused the protein to move from the prereplicative sites to the replication compartments, while inhibition of replication caused movement in the opposite direction. Thus, the blocking of a temperature-sensitive step precludes the synthesis of viral deoxyribonucleic acid and, therefore, the formation of mature virus. PCR and ISH allowed detection of oyster herpesvirus DNA in 93.3 and 86.6%, respectively, of analyzed oysters while polyclonal antibodies allowed detection of viral proteins in 76.6% of analyzed adult oysters. The onset of illness varied from day 0 to 42 days and was the result of different types of maternal infection (27 cases) and an external source (one case).
In conclusion, our findings indicate that HSV-1 and HSV-2 are shed into breast milk in a significant proportion of puerperals and breast-feeding may be an important route for the transmission of these viruses to infants.