Altered TLR7 Expression-Mediated Immune Modulation Is Supportive of Persistent Replication and Intrauterine Transmission of HBV.

Hepatitis B Virus (HBV) is posing as a serious public health threat mainly due to its asymptomatic nature of infection in pregnancy and vertical transmission. Viral sensing toll-like receptors ( TLR ) and Interleukins ( IL ) are important molecules in providing an antiviral state. The study aimed to assess the role of TLR7-mediated immune modulation, which might have an impact in the intrauterine transmission of HBV leading to mother to child transmission of the virus. We investigated the expression pattern of TLR7 , IL-3 , and IL-6 by RT-PCR in the placentas of HBV-infected pregnant women to see their role in the intrauterine transmission of HBV. We further validated the expression of TLR7 in placentas using Immunohistochemistry. Expression analysis by RT-PCR of TLR7 revealed significant downregulation among the Cord blood (CB) HBV DNA positive and negative cases with mean ± standard deviation (SD) of 0.43 ± 0.22 (28) and 1.14 ± 0.57 (44) with p  = 0.001. IL-3 and IL-6 expression revealed significant upregulation in the CB HBV DNA-positive cases with p  = 0.001. Multinomial logistic regression analysis revealed that TLR7 and IL-3 fold change and mother HBeAg status are important predictors for HBV mother to child transmission. Immunohistochemistry revealed the decreased expression of TLR7 in CB HBV DNA-positive cases. This study reveals that the downregulation of TLR7 in the placenta along with CB HBV DNA-positive status may lead to intrauterine transmission of HBV, which may lead to vertical transmission of HBV.