Phylogenetic and Mutational Analysis of the Tax Gene in the Human T-Lymphotropic Virus 1-Associated HAM/TSP in  Comparison with Asymptomatic Careers

Farzad  Babakhani; Atefeh  Bahavar; Soosan  Zare; Mohammad Ali  Sahraian; Abbas Rahimi  Foroushani; Seyed Mohammad  Jazayeri; Mahdi  Mohammaditabar; Ghazaleh  Molaverdi; Sayed-Hamidreza  Mozhgani; Mehdi  Norouzi

doi:10.18502/ijph.v54i2.17914

Farzad Babakhani Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
Atefeh Bahavar Department of Microbiology, Faculty of Medicine, Golestan University of Medical Sciences, Gorgan, Iran
Soosan Zare Sina Hospital, University of Tehran, Tehran, Iran
Mohammad Ali Sahraian MS Research Centre, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
Abbas Rahimi Foroushani Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
Seyed Mohammad Jazayeri Non-Communicable Diseases Research Center, Alborz University of Medical Sciences, Karaj, Iran
Mahdi Mohammaditabar Student Research Committee, Alborz University of Medical Sciences, Karaj, Iran
Ghazaleh Molaverdi Student Research Committee, Alborz University of Medical Sciences, Karaj, Iran
Sayed-Hamidreza Mozhgani Department of Microbiology, School of Medicine, Alborz University of Medical Sciences, Karaj, Iran
Mehdi Norouzi Research Center for Clinical Virology, Tehran University of Medical Sciences, Tehran, Iran

DOI: https://doi.org/10.18502/ijph.v54i2.17914

Keywords: Human T-lymphotropic virus 1 (HTLV-1); Phylogenetic analysis; Mutational analysis

Abstract

Background: Human T-lymphotropic virus 1 (HTLV-1) is a member of the Retroviridae family that can cause two groups of diseases: HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and adult T-cell leukemia/lymphoma (ATLL). Despite HTLV having seven different subtypes, cosmopolitan subtype A is responsible for most HTLV-1-related disorders and is the most widely dispersed type globally, including in the Middle East, known to be an endemic area for the virus. Therefore, due to the importance of determining the subtypes of this virus, we aimed to explore the subtypes of HTLV-1 in Iran.

Methods: In this cross-sectional study, we screened 140 Blood samples for HAM/TSP infection and approximately 4,500 samples for asymptomatic carriers (ACs) from Sina Hospital, Iran between 2020 and 2021. Positive samples were used for phylogenetic and mutational analysis to compare ACs and HAM/TSP cases via the Tax segment of HTLV. To identify the genotype of positive samples, the Maximum Likelihood method was used to construct the phylogenetic tree based on the positive samples.

Results: All Iranian isolates were clustered as HTLV-1a subgroups. Moreover, all of our samples have undergone positive selection pressure. Furthermore, we detected unique mutations in Iranian HAM/TSP and ACs sequences.

Conclusion: All of the Iranian Tax proteins are under positive selection pressure with respect to Japanese isolates. Interestingly, we detect specific mutation patterns in the sequences. Positions 51, 82, 109, 172, 232, and 339 in the aa sequence have undergone mutations specific to Iranian HTLV-1; and in positions 22 and 146 aa we detected mutations unique to ACs and HAM/TSP, respectively.