Dynamics of the NK-cell subset redistribution induced by cytomegalovirus infection in preterm infants

Human cytomegalovirus (HCMV) infection promotes an expansion of NK-cells expressing the CD94/NKG2C receptor. We prospectively monitored the effects of HCMV on the NK-cell receptor (NKG2C, NKG2A, KIR, LILRB1) distribution in preterm infants. As compared to non-infected moderately preterm newborns (n = 19, gestational age: 32–37 weeks), very preterm infants (n = 5, gestational age: <32 weeks) suffering symptomatic postnatal HCMV infection displayed increased numbers of NKG2C+, KIR+ NK-cells, encompassed by a reduction of NKG2A+ NK-cells. A similar profile was observed in HCMV-negative newborns (n = 4) with asymptomatic infection, during follow-up at ∼4 and 10 months of age. Of note, viremia remained detectable in three symptomatic cases at ∼10 months despite the persistent expansion of NKG2C+ NK-cells. Our study provides original insights on the dynamics of the imprint exerted by primary HCMV infection on the NK-cell compartment, revealing that the expansion of NKG2C+ NK-cells may be insufficient to control viral replication in very preterm infants.