Like SARS-CoV-2, human cytomegalovirus (HCMV) is a virus that causes only mild symptoms in most people it infects, but has the ability to cause severe problems in certain cases.

Most people around the world encounter HCMV as children. Infection is lifelong, and the virus usually remains latent. However, HCMV infection is a major cause of illness in organ transplant recipients, whose immune systems must be suppressed for transplants to be accepted. And children born with HCMV infection may also develop related congenital disorders, including childhood hearing loss and neurological problems. Development of new treatment strategies is still needed to address these complications.

Vaccines that stimulate an immune response against HCMV are one strategy to protect against infection by the virus. Potent virus-neutralizing antibodies are part of another strategy to treat HCMV infection. But the development of these strategies depends on our ability to answer questions about how the virus infects cells and how the immune system responds.

In a paper published in PLOS Pathogens, Xiaohua Ye and colleagues clarified answers to some questions about HCMV infections. They isolated antibodies that are part of a human donor’s response to a natural HCMV infection. Among these antibodies, they found one that was especially powerful at neutralizing the virus.

Other antibodies targeting the same region of the virus as the powerful antibody they discovered have been associated with protective immunity against HCMV disease in transplant recipients and infants at risk for congenital HCMV infection — two populations most affected by severe consequences from HCMV. This work advances our understanding of how antibodies neutralize HCMV, which will be helpful for the development of vaccines and antibody drugs against HCMV infection.