Fourteen heart transplant recipients were monitored for human cytomegalovirus (HCMV) infection based on determination of antigenemia, viremia, and DNAemia (by polymerase chain reaction [PCR]) in peripheral blood polymorphonuclear leukocytes (PMNL). Three patients had symptomatic primary, 10 had recurrent (3 asymptomatic), and 1 (seronegative) had no HCMV infection. Severe clinical symptoms appeared when levels of viremia/antigenemia were greater than 50 infected PMNL/2 x 10(5) cells examined. Of 200 blood samples examined, 93 (46.5%) were positive for viremia/antigenemia and DNAemia, whereas 48 (24.0%) were positive for DNAemia only; 59 (29.5%) were negative in all assays. Follow-up of HCMV infections in heart transplant recipients showed that PCR can detect viral appearance in blood 7-10 days earlier than assays for antigenemia/viremia. On the other hand, viral disappearance from blood, as assessed by PCR, occurred weeks or months later than revealed by other assays. Detection of virus by PCR only was never associated with overt HCMV-related clinical symptoms. Of the 8 symptomatic patients treated with ganiclovir, 2 became PCR-negative at the end of treatment and 1 cleared virus from blood in the following weeks, whereas 5 showed persistent or recurrent infection.

The genomic characteristics of human cytomegalovirus (HCMV) strains sequenced directly from clinical pathology samples were investigated, focusing on variation, multiple-strain infection, recombination, and gene loss. A total of 207 datasets generated in this and previous studies using target enrichment and high-throughput sequencing were analyzed, in the process enabling the determination of genome sequences for 91 strains. Key findings were that (i) it is important to monitor the quality of sequencing libraries in investigating variation; (ii) many recombinant strains have been transmitted during HCMV evolution, and some have apparently survived for thousands of years without further recombination; (iii) mutants with nonfunctional genes (pseudogenes) have been circulating and recombining for long periods and can cause congenital infection and resulting clinical sequelae; and (iv) intrahost variation in single-strain infections is much less than that in multiple-strain infections. Future population-based studies are likely to continue illuminating the evolution, epidemiology, and pathogenesis of HCMV.

Human cytomegalovirus (HCMV) was investigated in peripheral blood leukocytes (PBL) of 52 immunocompetent patients (40 pregnant women) with primary HCMV infection by quantitative determination of pp65 antigenemia, viremia, and leukoDNAemia. pp65 antigenemia was detected in 12 (57.1%) of 21, 4 (25%) of 16, and 0 of 10 patients examined 1, 2, and 3 months after onset, respectively. Viremia was detected in 5 (26.3%) of 19 patients during the first month only. LeukoDNAemia was detected in 20 of 20, 17 (89.5%) of 19, and 9 (47.3%) of 19 patients tested 1, 2, and 3 months after onset, respectively. Four (26.6%) of 15 patients were still DNAemia-positive at 4-6 months, whereas none were positive at >6 months. HCMV was not detected in PBL of 20 HCMV-immune donors or of 9 seropositive subjects with recurrent infection. Virus levels were low by all assays and did not correlate with clinical course of infection, intrauterine transmission, or severity of outcome. Invasive procedures in the presence of maternal leukoDNAemia did not seem to interfere with vertical transmission of HCMV infection.

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the combination of immunological and molecular assays is the most sensitive approach to the diagnosis of respiratory viral infections; and infections caused by the less investigated hCoVs and hMPVs represent a fair proportion of respiratory infections.

The development of adaptive T cell immunity after primary HCMV infection appears to be a complex and slow process until a memory T cell response develops. The T cell immune response appears to influence vertical HCMV transmission.

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IMPORTANCEThe management of mother-infant dyads during the ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic constitutes a major issue for neonatologists. In mothers with SARS-CoV-2 infection, current recommendations suggest either to separate the dyad or encourage protected rooming-in under appropriate precautions. No data are available regarding the risk of mother-to-infant transmission of SARS-CoV-2 during rooming-in.OBJECTIVE To evaluate the risk of postnatal transmission of SARS-CoV-2 from infected mothers to their neonates following rooming-in and breastfeeding. DESIGN, SETTING, AND PARTICIPANTSA prospective, multicenter study enrolling mother-infant dyads from March 19 to May 2, 2020, followed up for 20 days of life (range, 18-22 days), was performed. The study was conducted at 6 coronavirus disease 2019 maternity centers in Lombardy, Northern Italy. Participants included 62 neonates born to 61 mothers with SARS-CoV-2 infection who were eligible for rooming-in practice based on the clinical condition of the mother and infants whose results of nasopharyngeal swabs were negative at birth. EXPOSURES Mothers with SARS-CoV-2 infection were encouraged to practice rooming-in and breastfeeding under a standardized protocol to minimize the risk of viral transmission.MAIN OUTCOMES AND MEASURES Clinical characteristics and real-time reverse transcriptase-polymerase chain reaction for SARS-CoV-2 on neonatal nasopharyngeal swabs at 0, 7, and 20 days of life. RESULTSOf the 62 neonates enrolled (25 boys), born to 61 mothers (median age, 32 years; interquartile range, 28-36 years), only 1 infant (1.6%; 95% CI, 0%-8.7%) was diagnosed as having SARS-CoV-2 infection at postbirth checks. In that case, rooming-in was interrupted on day 5 of life because of severe worsening of the mother's clinical condition. The neonate became positive for the virus on day 7 of life and developed transient mild dyspnea. Ninety-five percent of the neonates enrolled were breastfed. CONCLUSIONS AND RELEVANCEThe findings of this cohort study provide evidence-based information on the management of mother-infant dyads in case of SARS-CoV-2 maternal infection suggesting that rooming-in and breastfeeding can be practiced in women who are able to care for their infants.