Search for possible routes of vertical infection of adult T-cell leukemia virus (ATLV): evidence of viral transmission from mother to child

Adult T-cell leukemia (ATL) in Japan is remarkably concentrated in adult T-cell leukemia virus (ATLV)-endemic areas and this limited distribution and other epidemiological analysis have strongly suggested the possibility of familial spreading of ATLV. I am interested in whether ATLV can be transmitted from mother to child and the possible routes of vertical infection of ATLV. I report here the results of a study on them. The results were as follows: No ATLV antigen-positive cells were detected at birth or 1, 3 or 6 months after birth. However, at later stages, the viral antigen-bearing cells became detectable. In 19 of 23 infants examined, the ATLV-positive cells were detected at 9 to 36 months after birth. The titers of antibodies to ATLV in the pairs of samples from mothers and their infants at birth were virtually equal, as expected. After birth, the titer of maternally derived antibody in all infants decreased gradually, and it disappeared within 3 to 9 months. However, ATLV-antibody reappeared in 12 of 24 infants examined, being detected after 12 months old. Further, it was shown that all breast milk samples derived from 12 seropositive mothers contained the ATLV which was capable of being transmitted to peripheral leukocytes of neonates.