Congenital Herpes Virus Tied to Common Childhood Cancer

Childhood acute lymphoblastic leukemia develops when the bone marrow makes too many immature white blood cells, stem cells that become lymphoblasts, B lymphocytes, or T lymphocytes.

It is widely suspected, yet controversial, that infection plays an etiologic role in the development of acute lymphoblastic leukemia (ALL), the most common childhood cancer and a disease with a confirmed prenatal origin in most cases. Children who develop ALL are over three times more likely to have tested positive for the common herpes virus cytomegalovirus (CMV) at birth.

Scientists at the University of California (Berkeley, CA, USA) and their colleagues first compared bone marrow infections in 127 children diagnosed with ALL, and in 38 children diagnosed with another type of leukemia, acute myeloid leukemia (AML). They used state-of-the-art methods to screen the samples for all known viruses and bacteria. They then used an ultra-sensitive digital droplet screen to test for CMV in newborn blood samples of 268 children who went on to develop ALL. They also tested newborn blood samples from 270 healthy children.

The team found genetic traces of CMV in abnormal white blood cells and intact virus particles in blood samples in the children with ALL, but rarely in those with AML. They found that the children who went on to develop ALL were 3.71 times more likely to be CMV-positive at birth. The odds were higher for Hispanic children who developed ALL as they were 5.9 times more likely to be CMV-positive at birth. They demonstrated active viral transcription in leukemia blasts as well as intact virions in serum.

Stephen S. Francis, PhD, an assistant professor and first author of the study said, “"If it's truly that in-utero CMV is one of the initiating events in the development of childhood leukemia, then control of the virus has the potential to be a prevention target. That's the real take-home message.” The study was published on December 15, 2016, in the journal Blood.

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