Real-Time PCR Quantification of Human Cytomegalovirus DNA in Amniotic Fluid Samples from Mothers with Primary Infection

Abstract

A real-time PCR assay was developed to quantify human cytomegalovirus (HCMV) DNA in amniotic fluid (AF) samples collected from 30 pregnant women with primary HCMV infection as detected either from HCMV-immunoglobulin G (IgG) seroconversion or by the presence of HCMV-specific IgG and IgM associated with a low IgG avidity. Clinical information available for each case included ultrasonographic examination and fetal or newborn outcome. HCMV infection of fetuses or newborns was confirmed for the 30 studied cases. AF samples were subdivided into three groups. In group A (n ‫؍‬ 13), fetuses presented major ultrasound abnormalities, and pregnancy was terminated. In group B (n ‫؍‬ 13), fetuses had normal ultrasound findings, the pregnancy went to term, and the newborns were asymptomatic at birth. In group C (n ‫؍‬ 4), fetuses had no or minor ultrasonographic signs, and pregnancy was terminated. The HCMV DNA load values in AF samples were significantly higher in group A (median, 2.8 ؋ 10 5 genome equivalents [GE]/ml) than in group B (median, 8 ؋ 10 3 GE/ml) (P ‫؍‬ 0.014). Our findings suggest that HCMV load level in AF samples correlates with fetal clinical outcome but might also be dependent on other factors, such as the gestational age at the time of AF sampling and the time elapsed since maternal infection.Human cytomegalovirus (HCMV) is the most common cause of viral intrauterine infection in developed countries, affecting 0.5 to 2% of all live births (1,32,40). Although the possibility of severe symptomatic fetal infection following recurrent maternal infection has been reported (8), fetal damage is mostly related to primary maternal infection (16,38,39). In this case, the transmission of the virus to the fetus may occur in 20 to 50% of pregnancies (18,27,38). It has been reported that HCMV transmission rates increase with gestational age and that a major risk of transmission is observed for seroconversion occurring late in pregnancy (5).Congenitally infected infants are asymptomatic at birth in about 90% of cases, and for symptomatic infants, infection ranges from mild to severe disseminated life-threatening disease resulting in up to 20% perinatal mortality (9,16,22,28,31,37). Up to 90% of the surviving symptomatic newborns will exhibit psychomotor and perceptual sequelae such as sensorineural hearing loss, mental retardation, cerebral palsy, seizures, and visual defects (2). Additionally, 10% of the infants who are asymptomatic at birth will later develop complications, mainly neurodevelopmental defects and deafness (7,15,40).The diagnosis of maternal primary HCMV infection is based mostly on serological testing, including HCMV immunoglobulin G (IgG) seroconversion and the presence of specific HCMV IgG and IgM (35). Moreover, the direct detection of viral components, including pp65 antigenemia and DNAemia, can be helpful for acute infection diagnosis. Prenatal diagnosis of HCMV congenital infection relies on virus isolation from amniotic fluid (AF) and/or viral DNA detection by PCR in AF samples (4,12,24,25,36,42)...

Clinical Predictive Value of Real-Time PCR Quantification of Human Cytomegalovirus DNA in Amniotic Fluid Samples

“…The value of the results of quantitative PCR for CMV in AF as a prognostic indicator of symptomatic congenital infection is even more controversial. Some authors have found that a high CMV viral load in AF is associated with a high risk of symptomatic infection in the fetus (13,15,19,20). Others, however, failed to demonstrate such an association (27,29,36), whereas still others proposed a possible association between the viral load…”

Prenatal Diagnosis of Congenital Human Cytomegalovirus Infection in Amniotic Fluid by Nucleic Acid Sequence-Based Amplification Assay

“…In general, both techniques have been shown to provide high specificity (96 to 100%) and good sensitivity (70 to 90%) (4,8,10,14,15), with the exception of a few reports from a single group showing low specificity and positive predictive value for PCR on AF samples (5,9). Since irrevocable decisions are often made on the basis of prenatal diagnosis, the use of a confirmatory assay is highly recommended.…”

Human Cytomegalovirus UL144 Gene Polymorphisms in Congenital Infections

“…Identification of other prognostic markers is therefore needed. The prognostic value of the HCMV load in amniotic fluid and in fetal blood is under evaluation (9,10,17,18). Characterization of HCMV strains, and particularly the analysis of a potential link between HCMV strain genotypes and disease severity, is also being investigated.…”