Determination of Cytomegalovirus Glycoprotein B Genotypes in Different Geographical Regions and Different Patient Groups in Turkey

Abstract

Cytomegalovirus (CMV), a common virus found all around the world, usually causes asymptomatic infections in immunocompetent hosts, however it may lead to serious complications in immunodeficient patients and in the fetus. CMV is divided into four genotypes according to the polymorphisms in UL55 gene that encodes for envelope glycoprotein B. Nucleotide polymorphisms of CMV gB gene can affect the cell tropism of the virus and host immune response and believed to have important changes in the pathogenesis of CMV. The aim of this study was to determine the gB genotypes of CMV isolates from different patient groups selected from different regions of Turkey. A total of 136 clinical specimens from patients (66 female, 70 male; age range: 0-65 years, mean age: 24.03 +/- 17.17) who were diagnosed to have CMV infection by polymerase chain reaction (PCR) and/or antigenemia tests, between 2001-2014, in the medical school hospitals of Akdeniz, Ege, Istanbul Cerrahpasa and Erciyes Universities (located at Mediterranean, Aegean, northwest and central Anatolia regions, respectively), were included in the study. The patient group consisted of 80 renal transplant (RT) recipients, 35 stem cell transplant (SCT) recipients, 13 newborns, seven heart transplant (HT) recipients and one pregnant woman. CMV gB genotypes were determined by PCR-RFLP (restriction fragment length polymorphism) method, and DNA sequencing and phylogenetic analysis were performed for the randomly selected 15 isolates with different genotypes. Among 136 (135 plasma, 1 amnion fluid) samples, the most frequent genotype was gB1 (n=44, 32.4%), followed by gB2 (n=39, 28.6%), gB3 (n=36, 26.5%) and gB4 (n=8, 5.9%); however nine (6.6%) samples could not be genotyped. When analysis were interpreted according to the patient groups, it was determined that the genotypes in RT recipients were gB1 32.3%, gB2 28.7%, gB3 26.5% and gB4 5.9%; in SCT recipients gB1 34.3%, gB2 28.6%, gB3 22.9% and gB4 5.7%; in HT recipients gB3 57.1%, gB1 14.3% and gB2 14.3%; in newborns gB1 38.4%, gB3 30.8%, gB2 15.4% and gB4 7.7%, and gB2 genotype in the pregnant woman. As our study was a descriptive study to determine the genotypes of CMV gB, the relationship between the genotypes and the variants such as viral load, symptomatic disease and prognosis were not analyzed. As a result, the isolation of different gB genotypes in various case groups from four distinctive provinces, underlines the diversity of CMV gB genotypes in Turkey.