Human Cytomegalovirus (HCMV) transcripts (including UL21.5 mRNA) have been found to be packaged in virions and their detection in plasma may indicate the presence of infectious viral particles. Objective of this study was to verify whether UL21.5 mRNA detected in the plasma was indeed encapsulated in viral particles, representing an indirect marker of active replication. To distinguish between virion-packaged and free-floating RNA, plasma samples from 22 immunocompromised patients were tested before and after ribonuclease (RNAse) digestion. UL21.5 mRNA was detected 1-2 weeks prior to preemptive therapy administration in 20 episodes (from 18 patients) of clinically significant DNAemia, while it was undetectable in three of the four patients with transient, self-resolving DNAemia. After RNAse digestion, UL21.5 mRNA was still detectable, with a median reduction of 0.1 (IQ range 0-0.3) Log 10. Concentrations of UL21.5 mRNA in plasma correlated significantly with HCMV DNA in whole blood or plasma (R=0.67), and 75% of samples positive for UL21.5 mRNA had HCMV DNA concentrations above 10 4 copies/ml blood or 10 3 copies/ml plasma. Moreover, UL21.5 mRNA was positive in patients who developed HCMV infection resistant to letermovir or maribavir, whereas it was undetectable in plasma of patients with transient self-resolving DNAemia blips during letermovir prophylaxis (not associated with drug-resistance). HCMV UL21.5 mRNA in plasma is virion-associated and represents a marker for productive HCMV infection. The determination of UL21.5 mRNA could improve current strategies for the management of HCMV infection in immunocompromised patients.

Postnatal cytomegalovirus (HCMV) infection is well characterized in preterm infants, where it can lead to severe symptomatic infection. We analyzed the rate and route of transmission of postnatal HCMV infections in full-term babies during the first year of life. A cohort of 120 HCMV seropositive mothers and their 122 newborns were tested after delivery for HCMV DNA shedding in different bodily fluids. Postnatal HCMV infection was defined as the detection of >2.5×10 2 HCMV-DNA copies/mL in infants’ saliva swabs. Maternal neutralizing antibody serum titer, HCMV specific T-cell response, and HCMV glycoprotein B (gB) IgG on breastmilk were analyzed. HCMV shedding was detected in 67 of 120 mothers (55.8%), and 20 of 122 infants (16.4%) developed HCMV infection within the first three months of life. Six additional infants were infected during the first year, for a postnatal infection rate of 21.3%. Viral shedding was more frequent in breastmilk than saliva, urine and vaginal secretions, and the mothers of infected infants showed higher levels of HCMV-DNA in milk. No association was found between the antibody levels in serum or milk and maternal viral shedding, whereas a slightly lower frequency of HCMV-specific CD4 + T-cells with long-term memory phenotype was observed in women with HCM-DNA-positive milk. About one out of five infants develop HCMV infection within the first year of life. Breastmilk appears the major route of transmission of the infection, maternal saliva have a minor role whereas the role of vaginal secretions is negligible.

Monkeypox virus (MPXV) is a zoonotic disease endemic in the rain forest countries of Central and West Africa. Understanding the immune response in zoonosis is fundamental to prevent and contrast viral spreading. MPXV is a close relative of the Variola (smallpox) virus and vaccination with vaccinia virus give an 85% protection against MPXV. With the emergence of the recent MPXV outbreak, Jynneos vaccine has been proposed to individuals at high-risk of exposure. Comparative data on MPXV immune response in vaccinated or infected subjects is still scarce. Here we described the differences between a group of infected patients in comparison to smallpox or Jynneos vaccinated subjects. The patients’ response is stronger and faster, while the Jynneos vaccinated controls need more time to develop a good immunity. Interestingly, the historic smallpox-vaccinated controls retain a degree of protection, even after years from vaccination, which is most visible in the T-cellular memory that is comparable to the newly vaccinated subjects.