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9/08/2025  |   11:30 AM - 12:30 PM   |  Breakout 1   |  Memorial Hall

Quantitation of HCMV DNA and infectious virus in saliva samples of young children in childcare centers

Abstract Summary

Introduction: Contact with young children who attend large group programs is a major risk factor for congenital human cytomegalovirus (HCMV) infection. The CMV Transmission and Immune Tracking (TransmIT) Study aims to understand HCMV spread within childcare centers to inform future efforts to reduce transmission from children to pregnant caretakers. We hypothesized that higher viral DNA loads would correlate with positive viral culture as a marker of saliva infectiousness. Methods: Children <36 months of age (n=64) were enrolled at 13 childcare centers. One saliva sample was collected from each child. Saliva was diluted in transport medium and processed for nucleic acid or stored for viral culture. HCMV DNA and replication were quantified by digital PCR (dPCR) and by modified shell vial assay (fibroblasts or epithelial cells), respectively. Results: HCMV DNA was detected by dPCR in 58 of 64 (90.6%) saliva samples. Of these, 21 (36.2%) had low (<10e3 copies/ml), 26 (44.8%) had medium (1x10e3–1x10e4 copies/ml), and 11 (19.0%) had high (>10e4 copies/ml) viral DNA loads. Viral replication was detected by shell vial assay in 47 of 64 (73.4%) samples and by DNA PCR in 47 of 58 (81.0%) samples. Unexpectedly, virus in only 24 (51.1%) of shell samples could infect both cell types, whereas 23 (48.9%) infected a single cell type (21 [44.7%] in fibroblasts and 2 [4.3%] in epithelial cells). Quantitative shell culture results revealed 0–1.04x10e5 infectious virus units/ml of saliva. Conclusions: Most young children in childcare settings shed infectious HCMV in saliva, but in varying amounts. In contrast to expected ability of HCMV to infect both cell types, nearly half of virus isolates could infect only one type, potentially reflecting in vivo differences in tropism. These findings highlight the importance of mitigating CMV transmission risk in large group childcare settings.

Learning Objectives

• Understand the prevalence and variable amounts of HCMV shedding in saliva among young children attending large group childcare centers.
• Evaluate the relationship between detection of HCMV genomes and of infectious virus in saliva.
• Discuss potential implications of observed cell type-specific HCMV infection for understanding viral transmission dynamics.

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