Preexisting Immunity to Common Virus Offers Protection Against Birth Defects and Miscarriage

 

Preexisting Immunity to Common Virus Offers Protection Against Birth Defects and Miscarriage

Researchers, including an Indian-origin scientist, have unveiled groundbreaking insights into the transmission of a common virus known for causing miscarriages and birth defects. Their findings open new doors for developing a vaccine that can safeguard both mothers and their infants.

Cytomegalovirus (CMV) is a prevalent herpesvirus that often infects women unknowingly before they reach child-bearing age. While typically benign, CMV poses a significant risk during pregnancy, where it can lead to miscarriages and a range of birth defects, including cerebral palsy and hearing impairment.

Scientists have long understood that women who contract CMV for the first time during pregnancy face the highest risk of complications. However, they have struggled to explain why individuals who already carry the virus are less susceptible.

A research team based at Tulane University in Louisiana, USA, has shed light on how pre-existing immunity to CMV plays a vital role in limiting transmission during pregnancy and protecting against related birth defects. Their findings, published in PLOS Pathogens, pinpoint the specific immune mechanisms responsible for this protection.

Dr. Amitinder Kaur, the principal investigator and a professor of microbiology and immunology, emphasized the importance of understanding how pre-existing immunity can shield against CMV transmission during pregnancy. This knowledge is pivotal in the development of an effective CMV vaccine capable of safeguarding pregnant women and their unborn children.

In their study, the team employed a nonhuman primate model closely resembling human CMV infection and transmission. When pregnant mothers were initially infected with CMV during the first trimester, all of them transmitted the virus to their offspring, leading to a high miscarriage rate. However, when nonhuman primates with prior CMV infections were reinfected during pregnancy, their offspring remained protected.

The mothers' robust immune response upon reinfection resulted in only one out of five mothers passing the virus through the placenta, with no adverse health outcomes observed in any of the infants. This research underscores that if a mother possesses CMV immunity before conceiving, her immune system can effectively shield her baby from congenital CMV transmission if she gets reinfected during pregnancy.

These findings hold immense promise for the development of a CMV vaccine aimed at preventing infections in pregnant women, particularly in regions with a high prevalence of CMV.