Genetic Basis for Clinical Manifestations of Onchocerca volvulus Infection among Displaced Patients from Southern

Abstract

Onchocerciasis is recognized by the World Health Organization as a major public health problem in many tropical countries with about17.7 million is estimated to be infected with O.volvulusworld-wide. It is one of the main problems in Sudan. Over two million are people believed to be infected with the disease in Sudan, mostly in the South, which includes some of the most highly endemic areas in the world. Onchocerciasis is associated with a spectrum of cutaneous and eye changes, ranging from clinically normal skin and eye to acute and chronic pathology. An important aspect of disease expression may be the level of immuneresponse to parasite antigens, which is likely to be regulated by MHC-encoded molecules. This study investigated the HLAclassII genotypes in of Southern Sudan suchan area endemic for onchocerciasis, using the polymerase chain reaction specific, sequences primers followed by gel electrophoresis. Ninety six subjects were recruited and allocated according to the skin conditions into generalized and localized onchocerciasis and into three groups according to their eye conditions, eye injection, diminished vision and itching eye. The five groups differed in distribution of HLA-classII determined by DNA typing. The DRB1*1301 and DQB1*0601 among patients with localized form were be found 50%, 55.5% and among control were 50% for DRB1*1301 and 44.5% for DQB1*0601. Among patients with generalized form of onchocerciasis, the alleles with high frequent were DRB1*1201 (100% in patient and not found in control), DQB1*0401 allele's genotypes and control were found: 50%, 50%. Among patients with diminished vision, clear eye injection and severe itching eye of onchocerciasis, the alleles DRB1*1102 and DQB1*0301 genotypes were more frequent 50%, 50% also among control 50%, 50% respectively. Among 4 patients with red eye injection, mild diminished vision and severe itching eye the alleles with high frequent were DRB1*1301 (distribution among control and patients were found: 50%, 44.5%, respectively) and DQB1*0601 (distribution among control and patients were found: 50% and 55.5%). The result indicated that individuals with depigmentation (localized form, severe itching eye, red eye injection, mild diminished vision) had increased frequencies of DQB1*0601 and DRB1*1301 when compared with control. Incontrast, individuals with generalized form of onchocerciasis had increased frequency of DQB1*0401 and DRB1*1202 compared with control. When individuals with mild itching eye, present diminished vision, clear eye injection had a decreased frequency of DRB1*1101 and DQB1*0601. These results strongly suggest that there is a monogenetic basis for the spectrum of cutaneous presentations and eye conditions in onchocerciasis and HLA-DR, DQ molecules are associated with these cutaneous. Alleles DRB1*01XX, DRB1*10XX and DQB1*01XX were shown exclusively in control (100%) it seems that they are working as protective genes on the other hand alleles DRB1*1201 and DRB1*0901 were only found in the patients (100%) but further investigation with large sample size is needed to verify this very interesting finding.