Identification of the CX3CRI gene polymorphism T280M in a sampled population of HIV infected persons from selected provinces in Kenya
Likhako, Felix Liyayi
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The Acquired Immunodeficiency Syndrome (AIDS) caused by the Human Immunodeficiency Virus (HIV), is one of the leading cause of morbidity and mortality in sub-Saharan Africa where about 22.9 million people accounting for over 68% of the infections worldwide are living with AIDS. It kills young economically productive individuals, causing hardship to families, increased expenditure on health care and adversely affects the economic growth in the region. There is still neither a cure nor a vaccine for HIV infection while the therapies used only delay the onset of AIDS. The Tcell recognition molecules CD4 act as receptors, the chemokine receptors CCR5 and CXCR4 ~s co-receptors for viral entry into target cells, whereas chemokine receptors CCR2, CCR3, CCR8, D6, RDC1 and CX3CR1 act as secondary coreceptors. Polymorphisms in chemokines and their receptors have been shown to influence the rate of infection, disease progression and viral suppression in individuals receiving antiretroviral therapy. Moreover, an allele mutation namely CCR5-~32 confers resistance against HIV-1 infection. This mutation results in a truncated protein devoid of cell surface receptor. The chemokine receptor CX3CR1 gene polymorphism T280M has been shown to increase susceptibility to HIV infection and progression to AIDS in French Caucasian studies. However, the existence of the polymorphism among Africans is still not fully understood. The im of thiLstudy w~s to, determine the prevalence and geographical distribution of T280M polymorphism in various regions in Kenya. Samples were collected from five provinces of Kenya, two with a high prevalence of HIV-1 (Western and Nyanza), two with a low prevalence (Central and North Eastern) and one cosmopolitan population (Nairobi) to determine whether this mutation exists. Whole blood samples from adults in these provinces were collected, genomic DNA extracted and CX3CR1 gene amplified using gene specific primers. BSMBI restriction enzyme was used to determine the existence of the T280M mutation in the sampled population. The results of this study show that T280M polymorphism exists in Kenya. The wild type phenotype had the highest frequency of 70% then heterozygous with a frequency of 28.5% while homozygous mutant were 1.5% in the population. Homozygous mutant was only found in Nyanza and Nairobi provinces. There is no significant difference in the geographical distribution of CX3CR1-280M polymorphism in the sampled population p=0.382. Pair wise analysis showed no significant difference in the prevalence of the polymorphism with province P>0.05. However, there is a trend towards high prevalence of T280M polymorphism in Nyanza and Western provinces compared to other regions. It was concluded that other factors therefore other than T280M polymorphisms are responsible for variation in the prevalence of HIV in the five provinces studied. The results of this study provide information for future studies on the prevalence and geographical distribution ofT280M polymorphism in different provinces of Kenya.
- MST-Zoological Sciences