Prevalence of human herpesvirus 6A and 6B during pregnancy.

The aim of the present study was to assess the frequency of human herpesvirus 6A (HHV-6A) and human herpesvirus 6B (HHV-6B) infection during pregnancy. 100-100 blood samples were collected from pregnant and non-pregnant women, then nucleic acid was isolated from both plasma and leukocytes fraction. Nested and real-time PCR were used to detect and differentiate HHV-6A and HHV-6B DNA and to determine viral loads. Reverse transcription PCR (RT-PCR) for HHV-6 U79/80 mRNA was performed in order to reveal active HHV-6 replication.HHV-6A and HHV-6B active infections were not detected in blood samples neither from pregnant nor from non-pregnant women. Frequency of HHV-6B and HHV-6A latency did not show difference between the studied groups (15% vs. 16%). HHV-6B latency was dominant in both studied groups (14/15 and 15/16). Beside these results, in leukocyte samples of one pregnant and three non-pregnant women high HHV-6A viral loads (1.28 × 10⁵ - 5.07 × 10⁵ GEq / 1.5 × 10⁶ leukocytes) were detected, and viral DNA was also found in plasma samples. Although RT-PCR did not confirm virus replication, but chromosomal integration was also not proved unequivocally, the number of 0.08-0.33 HHV-6 copy / 1 leukocyte refers more to postnatal infection.