Cytomegalovirus diversity among patients of all ages in Johannesburg, South Africa, 2022-2023

Abstract

Background: Cytomegalovirus (CMV), a common deoxyribonucleic acid (DNA) viral DNA pathogen with diverse genotypes, can possibly and significantly affect the severity of the disease and treatment outcomes. Accurate and reliable glycoprotein B (gB) genotype detection is important in understanding the epidemiology of CMV infection and disease. Methods: A total of 111 specimens were collected from patients who accessed care in public and private healthcare settings in Johannesburg, South Africa for CMV related illness. Study samples were tested for CMV using the Argene CMV-R gene real-time PCR detection kit. Thereafter CMV positive samples underwent genotyping using an in-house real-time multiplex PCR, targeting gB1, gB2, gB3, and gB4. Samples that failed genotyping were further analysed using conventional PCR followed by sequencing. In addition, some CMV positive samples were selected for amplification and sequencing of the unique long (UL) 54 and UL97 genes to identify mutations associated with drug resistance. Results: Among the total study population 25/111 (23%) were excluded due to sample haemolysis or insufficient volume. From the remaining 86/111 (77%) tested for CMV, 86% (74/86) tested positive. The gB3 genotype was the most prevalent at 77% (57/74). No single gB2, gB1 and gB4 genotypes were detected. Mixed genotype infections were detected in 6.7% (5/74) of patient samples. Unfortunately, we were unable to generate UL54 and UL97 sequence data to analyse for drug resistance. Discussion and Conclusions: Our analysis revealed genotype gB3 as the predominant strain within the study population. The presence of mixed infections in 6.7% of samples highlights the complex nature of CMV epidemiology. Overall, this research enhances the understanding of CMV genetic diversity, which is important for informing targeted public health and treatment strategies.