The paired analysis classified 135 tumors, or 61.1%, as IE1-high and 124, or 56.1%, as UL123-positive. IE1-high status was observed in 74.8% of grade III–IV gliomas compared with 31.4% of grade I–II tumors. The corresponding UL123-positive proportions were 70.2% and 25.7%. Both assays also identified markers more frequently in patients aged 50 years or older, in tumors lacking the IDH1 R132H mutation, and among those with a preoperative Karnofsky Performance Status below 80. Neither marker showed a significant association with sex. These findings extend earlier reports that HCMV proteins and nucleic acids can be detected in some gliomas, although other studies have reported little or no signal using different methods.

Immunohistochemistry detected IE1 in the nuclei and cytoplasm of tumor cells. Investigators combined staining intensity, scored from zero for no staining to three for strong staining, with the proportion of stained cells to produce a final score of zero to 12. Tumors scoring four or higher were classified as IE1-high, while those scoring below four were IE1-low. Three pathologists, blinded to the PCR results and patient outcomes, evaluated the sections and resolved disagreements by joint review. A nonimmune mouse immunoglobulin G control was used in place of the primary antibody. Positive cells were generally sparse and weakly stained in low-grade tumors, whereas staining was more widely distributed and conspicuous in high-grade tumors.

UL123 DNA was measured in triplicate by quantitative real-time PCR, with the mean cycle threshold value used to classify each sample. A mean Ct below 35 was considered UL123-positive, and a value of 35 or above was considered negative. Melting-curve analysis was used to assess amplification specificity. The assay documentation did not establish sample-specific DNA amplifiability in UL123-negative specimens, so a negative result could reflect low viral DNA, DNA degradation, or PCR inhibition rather than complete absence of the virus. The operational cutoff was not analytically validated, an important qualification because threshold choice can materially affect detection rates and group assignments.

The protein and DNA assays produced the same binary classification for 162 of the 221 paired specimens, corresponding to 73.3% agreement. Cohen’s kappa was 0.451, indicating an association beyond chance but not enough agreement for the tests to be treated as interchangeable. There were 100 double-positive and 62 double-negative samples, while 35 tumors were positive only by immunohistochemistry and 24 only by PCR. The paired positive rates did not differ significantly overall, with a McNemar P value of 0.193, and the assays remained associated when results were separated by tumor grade, age, or sex. Possible explanations for discordance include uneven distribution of viral material within a tumor and the detection of protein when DNA levels fall below the PCR threshold, but neither mechanism was directly tested.

Kaplan–Meier analysis showed substantially lower survival estimates among patients whose tumors were positive for either marker. At 36 months, estimated overall survival was 25.9% in the IE1-high group and 54.7% in the IE1-low group. Median overall survival was 18.2 months for IE1-high patients, while the median was not reached in the IE1-low group; the log-rank P value was below 0.001. For UL123, 36-month survival was 25.0% among positive cases and 52.6% among negative cases, with medians of 16.7 months and not reached, respectively, and again a P value below 0.001. These were unadjusted comparisons, and the study did not report hazard ratios or confidence intervals.

Patients whose tumors were positive by both assays had the poorest observed outcomes. Among the 162 concordant cases, 36-month overall survival was 21.0% for the 100 double-positive patients and 59.7% for the 62 double-negative patients, with a log-rank P value below 0.001. Median survival was 15.6 months in the double-positive group and was not reached in the double-negative group. The same pattern appeared within both grade categories. In grade I–II disease, estimated 36-month survival was 9.1% for double-positive cases and 56.1% for double-negative cases; in grade III–IV disease, the figures were 22.5% and 66.7%. The combined survival analysis excluded 59 patients with discordant results, so its estimates apply specifically to patients with matching assay classifications.

Several factors prevent the observed survival differences from being interpreted as an independent prognostic effect of HCMV. Older age, lower preoperative performance status, higher grade, and IDH1 wild-type status were themselves associated with worse outcomes and were unevenly distributed between marker groups. The analysis did not use multivariable survival adjustment, did not include postoperative treatment or extent of resection, and used a Ct threshold without analytical validation. It also grouped tumors mainly by histologic grade rather than by fully integrated contemporary molecular classification, while IDH1 R132H testing alone does not identify every IDH1 or IDH2 mutation. More aggressive tumors may make viral markers easier to detect, and marker status could partly reflect tumor biology rather than drive progression.

The study’s principal strength is its paired testing of protein and DNA in a relatively large, single-center glioma cohort, including grade-stratified clinicopathological and survival analyses. Its main limitations are the need for independent replication, potentially influential tissue-selection and assay procedures, incomplete control documentation for negative PCR results, and the absence of adjusted survival models. Future studies should use blinded testing with predefined thresholds, validate PCR amplifiability, examine additional viral DNA targets and multiple regions of each tumor, apply current integrated tumor classifications, and report adjusted hazard estimates and confidence intervals. Until such validation is available, IE1 protein and UL123 DNA should be regarded as investigational markers associated with aggressive glioma features and poorer observed survival, rather than proven causes of disease or clinically ready prognostic tools.

Subject of Research: HCMV IE1 protein and UL123 DNA associations with glioma features and overall survival

Article Title: Association of HCMV IE1 protein and UL123 DNA with clinicopathological features and survival in patients with glioma

Article References: Hao, Z., Liu, Q., Guo, Y., Zhang, J., Ding, R., Chen, L., & Yin, X. (2026). Association of HCMV IE1 protein and UL123 DNA with clinicopathological features and survival in patients with glioma. Frontiers in Cellular and Infection Microbiology, 16, Article 1975136. https://doi.org/10.3389/fcimb.2026.1975136

Image Credits: AI Generated

DOI: 10.3389/fcimb.2026.1975136

Keywords: human cytomegalovirus, glioma, IE1 protein, UL123 DNA, immunohistochemistry, quantitative PCR, overall survival, IDH1 status, tumor grade, Association, HCMV, protein