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Human cytomegalovirus (HCMV) displays genetic polymorphisms. This variability may contribute to strain-specific tissue tropism and disease expression in HCMV-infected humans. To determine strain variability in a sequence and UL144 gene regions, 51 low-passage isolates from 44 HCMV-infected children were studied. Isolates were obtained from 28 healthy children attending child care centers in Iowa and from 16 congenitally infected infants born in Texas. Isolates demonstrated substantial nucleotide variation in each gene region. Phylogenetic analysis of a sequence variability allowed 39 isolates to be grouped into six clades. The largest clade contained 16 isolates with > or = 95% nucleotide homology. Forty-eight of the 49 HCMV isolates yielding UL144 amplicons was grouped according to the clades described a few years ago [Lurain et al. (1999) Journal of Virology 73:10040-10050]. No linkage was observed among a sequence, UL144, and glycoprotein B (gB; UL55) polymorphisms. Four Texas and 11 Iowa isolates displayed > or = 95% sequence homology for a sequence and UL144 regions and possessed identical gB genotypes. No relationship between UL144 polymorphisms and outcome of congenital HCMV infection was observed. These data indicate that HCMV strains circulating among young children have UL144 polymorphisms similar to those of HCMV strains excreted by immunocompromised adults. Identification of conserved nucleotide sequences among Iowa and Texas children suggests genetic stability and biologic importance of these gene regions.

To determine factors that influence the occurrence of congenital cytomegalovirus (CMV) infection, the authors surveyed prospectively 8,254 infants born in eastern Iowa between October 1989 and June 1994. The authors conducted a case-control study to identify maternal risk factors, matching each CMV-infected infant with three uninfected infants according to hospital and date of birth. CMV strains were compared by using the polymerase chain reaction (PCR) to identify common sources of infection. Of the 7,229 infants cultured successfully for CMV, 35 (0.48%) were congenitally infected. Mothers of CMV-infected infants were more likely to be single (odds ratio (OR) = 3.05, p = 0.016), to work in sales (OR = 4.93, p = 0.008), or to be students (OR = 5.01, p = 0.017). Conversely, women who worked in health-care professions were less likely to have a congenitally infected infant (OR = 0.14, p = 0.049). PCR analysis indicated 27 distinct strains of CMV, but two groups of infants (two infants per group) excreted strains with indistinguishable molecular patterns. One of these pairs of infants had older siblings who attended the same child-care center during their mothers' pregnancies. The authors concluded that demographic and occupational factors influenced the risk of giving birth to an infant with congenital CMV infection. Many distinct CMV strains were identified, suggesting that major point source outbreaks had not occurred. Nonetheless, point source acquisition of CMV from child-care environments did account for some cases of congenital CMV infection in eastern Iowa.

Human cytomegalovirus (HCMV) strains display genetic polymorphisms, and these polymorphisms can be analyzed to study viral transmission and pathogenesis. Recently, short tandem repeat (STR) length polymorphisms have been identified in the HCMV genome. We assessed the utility of STRs in characterizing HCMV strains and found that a multiplexed PCR assay using primers based upon these STRs accurately maps HCMV strains. Using primers for 10 microsatellite regions, the STR profiles of 44 wild-type and 2 laboratory strains of HCMV were characterized. The results of STR analysis were compared with those for strain characterization using nucleotide sequencing and restriction fragment length polymorphism analysis. In each instance, STR analysis accurately and specifically identified strains that were indistinguishable or distinct by conventional molecular analysis. Analysis of short tandem repeats also detected polymorphisms that supported simultaneous excretion of two HCMV strains. These results indicate that STR analysis allows rapid, precise molecular characterization of HCMV strains.Human cytomegalovirus (HCMV), a betaherpesvirus, has a large, complex genome consisting of approximately 240,000 nucleotide base pairs (bp) and over 200 open reading frames (20). Wild-type and laboratory strains of HCMV display nucleotide polymorphisms in several regions of the genome, especially in the a sequence, major immediate early (MIE), glycoprotein B (gB; UL55), and UL144 gene regions (7,8,12,(16)(17)(18); J. F. Bale, S. J. Petheram, M. Robertson, J. R. Murph, and G. Demmler, submitted for publication). Although the effects of these polymorphisms on the biology of HCMV infections are largely unknown, molecular variations can be analyzed to study the epidemiology and pathogenesis of HCMV infections (4,5,16).Mapping the molecular profiles of HCMV has enabled investigators to determine the source and transmission patterns of HCMV infections. Studies of HCMV epidemiology have mapped strains by using analysis of the restriction fragment length polymorphisms (RFLPs) of the entire HCMV genome (1, 10), PCR-based analysis of a sequence variations (2, 22), DNA sequence analysis of polymorphic regions (11,19; Bale et al., submitted), and stepwise analysis of the RFLPs of gene regions by using PCR-based methods (3,7,15,18). Our laboratory has previously used a PCR-based algorithm that compares the size and RFLPs of the a sequence amplicon, the gB genotype as described by Chou and Dennsion (8), and the RFLPs of an amplicon derived by amplification of the MIE gene region (18). Although these molecular approaches can characterize HCMV strains accurately, they are time-consuming and available only in research laboratories.Recently, Davis and colleagues reported that the HCMV genome contains numerous short tandem repeats (STRs) (9). The microsatellite regions consist of iterated motifs of one to six bases that occur in the genomes of eukaryotes and some prokaryotes and represent potential sites of mutation (14, 21). Davis and colleagues found at ...

Intrauterine infection with cytomegalovirus (CMV), a betaherpesvirus, remains the most frequent congenital virus infection in many regions of the world. Although most CMV-infected newborns lack signs of CMV infection, approximately 10% have signs that can consist of low birth weight, jaundice, hepatosplenomegaly, skin rash, microcephaly, and chorioretinitis. Neonates with signs of CMV infection at birth have high rates of audiologic and neurodevelopmental sequelae. Although postnatal therapy with ganciclovir transiently reduces virus shedding and may lessen the audiologic consequences of CMV in some infected infants, additional strategies are needed to prevent congenital CMV disease and to improve the neurodevelopmental prognosis of infants infected with CMV in utero. Some cases of intrauterine infections can be prevented in susceptible women by avoiding contact with the urine or saliva of young children who may be shedding CMV. Vaccines against CMV remain in the experimental stages of development. Termination of pregnancy can be offered to women whose infants have evidence of intrauterine CMV infection and sonographic signs of central nervous system damage. Infants who survive symptomatic intrauterine infections have high rates of neurodevelopmental sequelae and require comprehensive evaluation and therapy through center and home-based early intervention programs.