Identification of a highly conserved region in the human cytomegalovirus glycoprotein H gene and design of molecular diagnostic methods targeting the region

Rapid and sensitive point-of-care diagnosis of human cytomegalovirus infection using RPA-CRISPR technology

Background

Human cytomegalovirus (HCMV) is a common herpesvirus that can cause a range of symptoms, from mild conditions such as fevers to severe illnesses like pneumonia. Early and accurate diagnosis of HCMV infection is crucial, particularly for vulnerable populations with limited medical care. However, current diagnostic methods are often expensive, time-consuming, and require skilled technicians.

Materials and methods

We developed an HCMV-RPA-CRISPR diagnosis platform for the rapid and cost-effective detection of HCMV infection. This method utilizes recombinase polymerase amplification (RPA) to amplify the HCMV target gene isothermally without the need for thermal cycling equipment. The platform integrates the CRISPR/Cas12a system, significantly enhancing specificity and sensitivity. A total of 13 clinical blood samples were tested to evaluate the platform's effectiveness and accuracy. Additionally, a lateral flow assay (LFA) and fluorescence detection were incorporated for straightforward and rapid visual interpretation of the results.

Results

The assay effectively detected concentrations as low as a single copy of the positive control plasmid per microliter in under 1 h, without requiring specialized equipment or training. In clinical sample evaluations, both the fluorescence readout and LFA exhibited 100% sensitivity and specificity, identifying four HCMV-positive and nine HCMV-negative samples.

Conclusion

The HCMV-RPA-CRISPR diagnosis platform is comparably effective to qPCR for HCMV diagnosis. Its applicability in common clinical laboratories, clinics, and point-of-care settings, particularly in resource-limited environments, makes it a valuable tool for widespread HCMV screening and diagnosis.

Microwave treatment of breast milk for prevention of cytomegalovirus infection

BACKGROUND

Breast milk (BM) is the best nutrition for very preterm infants (VPI), except when provided by human cytomegalovirus (HCMV)-seropositive mothers. Given that VPI are at high risk of developing a sepsis-like syndrome or cholestasis, methods for prevention of HCMV infection via BM have been investigated. Although Holder pasteurization (HP) is the gold standard, HP needs special instruments. Microwave (MW) is available anywhere, therefore, we performed this study to determine whether MW can be used for HCMV prevention.

METHODS

Human cytomegalovirus Towne strain was added to formula, followed by heating procedure using HP or MW (at 500 W for 20, 30, 40, or 60 s). HFL-III cells were seeded in culture dishes. Aliquots of HCMV-milk samples after heating were inoculated onto susceptible cell monolayers. The number of plaques was counted to determine the viral titer. The determination of HCMV-DNA copies was also performed.

RESULTS

Addition of HCMV for a viral load of 5.0 × 10³ plaque-forming units (p.f.u.)/mL achieved 772 p.f.u./mL at baseline, with a decrease to 257 p.f.u./mL after MW radiation for 20 s. No plaque was detected after HP or MW for 30, 40, and 60 s. The temperature of the breast milk reached 60°C after MW radiation for 40 s. The number of HCMV-DNA copies did not change with MW.

CONCLUSIONS

Microwave at 500 W for 40 s can be used as a prevention strategy for HCMV transmission. Further research including the loss of bioactive properties in BM is required prior to clinical application.

Newborn Congenital Cytomegalovirus Screening Based on Clinical Manifestations and Evaluation of DNA-based Assays for In Vitro Diagnostics

OBJECTIVES

To establish a strategy for congenital cytomegalovirus (cCMV) screening and to establish confirmatory assays approved as in vitro diagnostics by the regulatory authorities, we evaluated the clinical risks and performance of diagnostic assays developed by commercial companies, since cCMV infection has significant clinical consequences.

STUDY DESIGN

Newborns with clinical manifestations considered to be consequences of cCMV infection (n = 575) were screened for the presence of cytomegalovirus (CMV) DNA in urine specimens collected onto filter paper placed in their diapers using the polymerase chain reaction-based assay reported previously. Liquid urine specimens were obtained from all of 20 CMV-positive newborns and 107 of the CMV-negative newborns identified in the screening. We used these 127 specimens, as well as 12 from cCMV cases identified in a previous study and 41 from healthy newborns, to compare the performance of 2 commercial assays and 1 in-house assay.

RESULTS

The risk-based screening allowed the identification of cCMV cases at least 10-fold more efficiently than our previous universal screening, although there appears to be a limit to the identification of asymptomatically infected newborns. Although CMV-specific IgM during pregnancy was found frequently in mothers of cCMV newborns, CMV-IgM alone is not an effective diagnostic marker. The urine-filter-based assay and the 3 diagnostic assays yielded identical results.

CONCLUSIONS

Although risk-based and universal newborn screening strategies for cCMV infection each have their respective advantages and disadvantages, urine-filter-based assay followed by confirmatory in vitro diagnostics assays is able to identify cCMV cases efficiently.

Presence of cytomegalovirus in the perilymphatic fluid of patients with profound sensorineural hearing loss caused by congenital cytomegalovirus infection

CONCLUSION

Not all patients diagnosed with congenital infection using umbilical cord assay were found to be positive for CMV-DNA by perilymphatic fluid assay. In addition, a CMV-DNA-positive result was observed in one patient who had not been diagnosed with congenital infection. Sampling of perilymphatic fluid from a large population of patients with congenital SNHL caused by congenital CMV infection or of unknown etiology is required to determine the prevalence of CMV-related profound HL.

OBJECTIVES

Sensorineural hearing loss (SNHL) is one of the most frequent manifestations in patients with congenital cytomegalovirus (CMV) infection. Using dried umbilical cord, a PCR-based assay was recently developed for the retrospective detection of congenital CMV infection. This study analyzed the presence of CMV in the perilymphatic fluid and evaluated differences in the effect of cochlear implantation between CMV-positive and -negative groups.

METHOD

Perilymphatic fluid was collected from each patient at the time of cochlear implantation and analyzed for the presence of CMV using a PCR method.

RESULTS

The perilymphatic fluid in two of the five patients suffering from congenital CMV infection and in one of the 17 patients without congenital CMV infection was found to be positive for CMV.

A novel real-time PCR method for determination and quantification of each cytomegalovirus glycoprotein H subtype in clinical samples

To investigate reinfection in patients with congenital cytomegalovirus (CMV) infection, we established a CMV subtype-specific real-time quantitative PCR method targeting the CMV gH epitope region that can be used for evaluating pathogenic CMV strains in cases of mixed CMV infection.

The quantitative detection of herpes simplex virus, varicella zoster virus, and cytomegalovirus DNAs in recipient corneal buttons

PURPOSE

We detected herpes simplex virus types 1 (HSV-1) and 2 (HSV-2), varicella zoster virus (VZV), and cytomegalovirus (CMV) DNAs in recipient corneal buttons taken at the time of penetrating keratoplasty.

METHODS

Twenty-seven corneal buttons were obtained from 27 patients (10 men and 17 women), 7 of whom had a history of HSV keratitis. Excised corneal buttons were immediately frozen in liquid nitrogen in the operating theater and then stored at -80°C until DNA extraction. The detection of HSV-1, HSV-2, VZV, and CMV DNAs was carried out by a nested polymerase chain reaction (PCR) method. The genome copy numbers for the nested PCR-positive samples were subsequently quantified by real-time PCR.

RESULTS

HSV-1, HSV-2, VZV, and CMV DNAs were detected in 10, 1, 9, and 2 of the 27 recipient corneal buttons, respectively. HSV-1 or HSV-2 DNAs were also detected in 5 of 7 patients with a history of HSV keratitis. Both CMV-positive patients (patients 2 and 3) had ocular pemphigoid. Among the nested PCR-positive samples, 2 HSV-1, 1 HSV-2, 1 VZV, and 1 CMV sample could be quantified by real-time PCR. Copy numbers ranged from 19 to 928 copies.

CONCLUSIONS

All 4 herpesviruses, including CMV, were detected in the corneal buttons. The relationship between CMV in the cornea and ocular diseases of the anterior segment should be further evaluated.

Monitoring human cytomegalovirus infection with nested PCR: comparison of positive rates in plasma and leukocytes and with quantitative PCR

BACKGROUND

Human cytomegalovirus (HCMV) infection poses a significant health threat to immunocompromised individuals. Here we performed this study to set up a highly sensitive nested PCR method applicable for detecting HCMV infection in high-risk individuals. In this work, 106 blood specimens from 66 patients with potential HCMV infection were obtained. Total DNA was extracted separately from plasma and peripheral blood leukocytes (PBL) of each sample. HCMV DNA was detected in parallel by nested PCR and quantitative real-time PCR (qRT-PCR), and the results were compared.

RESULTS

Serial dilution test revealed that the detection limit of nested PCR was 180 copies/ml. The nested PCR showed a higher positive rate than qRT-PCR (34.9% vs. 12.3%, p < 0.001). The positive rate of nested PCR based on PBL DNA was significantly higher than that based on plasma DNA (34.9% vs. 18.9%, p = 0.002). Of the 14 patients with serial samples, 11 were positive for HCMV DNA in PBL while only 7 were positive in plasma. Moreover, for each patient, nested PCR using PBL DNA also detected more positive samples than that using plasma DNA.

CONCLUSION

Combined use of nested PCR with PBL DNA is highly sensitive in defining HCMV infection. This assay is particularly useful in the case of quantification not essential.

Association between antibody response against cytomegalovirus strain-specific glycoprotein H epitopes and HLA-DR

The gH of CMV is a major target for strain-specific neutralizing antibodies. To verify whether there is a correlation between HLA-DR type and strain-specific antibodies, antibodies against CMV gH in potential donors and recipients for renal transplantation were investigated. Among 471 subjects, 404 (86%) showed reactivity to CMV gH, but no antibodies against gH were detected in 67 (14%) subjects. The positive rates were over 80% in most HLA subpopulations. Fewer subjects with HLA-DR10 and DR11 had antibodies to CMV gH than did those without HLA-DR10 and DR11. HLA-DR10 and DR11 may be associated with fewer/non-responders for strain-specific neutralizing antibodies.

Clinical predictive value of real-time PCR quantification of human cytomegalovirus DNA in amniotic fluid samples

The aim of this study was to evaluate the diagnostic reliability and prognostic significance of the quantification of cytomegalovirus (CMV) DNA in amniotic fluid (AF). We retrospectively reviewed the results for 282 amniotic fluid samples that had been tested for CMV by a quantitative real-time PCR. We observed three cases in which no CMV genomes were detected in the AF but in which the children were nevertheless congenitally infected. Hence, we conclude that a negative result by PCR for CMV in AF cannot rule out the possibility of congenital infection. No false-positive PCR results were observed. A correlation between the CMV viral load in AF and the fetal and neonatal outcomes could not be demonstrated in our study. Instead, a correlation was found between the CMV viral load and the gestational age at the time of amniocentesis.