Reactivation of Betaherpesvirinae (Human herpesvirus 6A: HHV-6A, -6B, HHV-7) may be associated with mental illness and host fatigue. This study aimed to determine whether viral reactivation, measured by monitoring salivary viral DNA load, can be used to monitor depression in pregnant and postpartum women. Saliva samples were collected from 64 pregnant women at five points of observation periods. The HHV-6- and HHV-7-specific qPCRs were carried out to measure viral DNA load. When HHV-6 DNA was detected in saliva, nested PCR was used to discriminate between HHV-6A and -6B. In both viruses, a significant correlation was observed between detection frequency and viral DNA load in saliva. In the low-shedding group, HHV-6 DNA was significantly higher in the third trimester (p < 0.0001), the time of delivery (p = 0.0003), 1 month after birth (p = 0.0023) compared with the first trimester, and HHV-7 was at the time of delivery (p = 0.0277) and 1 month after birth (p = 0.0235). Most of the detected HHV-6 DNAs in saliva were HHV-6B. Both viral DNA loads were significantly lower (HHV-6: p = 0.0101, HHV-7: p = 0.0044) in the subjects with abnormal Edinburgh Postnatal Depression Scale (EPDS) scores. The detection rate and viral DNA load of both viruses in saliva increased after the third trimester. Salivary virus DNA shedding was significantly lower in subjects with an abnormal EPDS score.
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