Comparison Cytomegalovirus Qualitative Assay Using Real-Time PCR and Conventional PCR

Loop-mediated isothermal amplification assay for screening congenital cytomegalovirus infection in newborns

Congenital cytomegalovirus (CMV) infection is a common cause of sensorineural hearing loss and neurodevelopmental impairment in newborns. However, congenital CMV infection cannot be diagnosed using samples collected more than 3 weeks after birth because testing after this time cannot distinguish between congenital infection and postnatal infection. Herein, we developed a robust loop-mediated isothermal amplification (LAMP) assay for the large-scale screening of newborns for congenital CMV infection. In contrast to conventional quantitative polymerase chain reaction (qPCR), which detects CMV within a dynamic range of 1.0 × 106 to 1.0 × 102 copies/μL, our quantitative LAMP assay (qLAMP) detects CMV within a dynamic range of 1.1 × 108 to 1.1 × 103 copies/μL. Moreover, the turnaround time for obtaining results following DNA extraction is 90 min in qPCR but only 15 min in qLamp. The colorimetric LAMP assay can also detect CMV down to 1.1 × 103 copies/μL within 30 min, irrespective of the type of heat source. Our LAMP assay can be utilized in central laboratories as an alternative to conventional qPCR for quantitative CMV detection, or for point-of-care testing in low-resource environments, such as developing countries, via colorimetric naked-eye detection. KEY POINTS: • LAMP assay enables large-scale screening of newborns for congenital CMV infection. • LAMP allows colorimetric or quantitative detection of congenital CMV infection. • LAMP assay can be used as a point-of-care testing tool in low-resource environments.

Clinical characteristics and treatment courses for cytomegalovirus-associated thrombocytopenia in immunocompetent children after neonatal period

Background

Cytomegalovirus (CMV) causes severe diseases in premature infants and immunocompromised hosts, and antiviral therapy is often required for disease control. However, the clinical manifestations and treatment courses for CMV-associated thrombocytopenia in immunocompetent children are unclear.

Methods

Medical records of the children who suffered from thrombocytopenia, and showed positive CMV polymerase chain reaction and CMV-like symptoms were retrospectively analyzed at three university hospitals in Daegu from January 2000 to March 2017. Patients suffering from leukemia, immunodeficiency, and other infections were excluded.

Results

Among 1,065 children with thrombocytopenia, 29 (2.7%) displayed CMV-associated thrombocytopenia. The median age at diagnosis was 15 months and the median platelet count was 26,000/µL. They were classified into the CMV-induced thrombocytopenia (23/29) and CMV-related secondary immune thrombocytopenia (ITP, 6/29) groups. Fourteen subjects had hepatic dysfunction, four had Evans syndrome, two had pneumonitis, and one had gastritis. IVIG was used for 21 patients, and six patients among them showed recurrence, for whom IVIG or antiviral therapy was used. All, except one, recurrent or chronic cases belonged to the CMV-induced thrombocytopenia group. Antiviral therapy was used more frequently for the CMV-induced thrombocytopenia group (8/23, 34.8%) than for the CMV-related secondary ITP group (0/6); however, the results were not statistically significant (P=0.148).

Conclusion

CMV is a rare but unique etiology of thrombocytopenia, and observed even in healthy children after the neonatal period. About one-third patients need antiviral therapy for disease control. Further, CMV-induced thrombocytopenia is more complex than CMV-related secondary ITP.