Knowledge and DdeI Based Confirmation of Sickle Cell Anemia Among the Tharu Community.

BACKGROUND: Sickle cell anemia is an inherited blood disorder caused due to a point mutation at the sixth codon of the ?-globin gene of both alleles. Sickle cell traits occur when the mutation is in one of the two alleles of the ?-globin genes. This study was carried out in the Tharu community, which is an indigenous and minority group mostly residing in the Terai region of Nepal. They are also considered as the most vulnerable group for inheriting Sickle cell anemia. METHODS: Purposive sampling, which included 130 Tharu individuals of Kanchanpur district of Nepal, was considered for the study. The survey was conducted using a descriptive questionnaire that contained relevant information including the family history of Sickle cell anemia. This was followed by the analysis of blood samples to determine the prevalence of Sickle cell anemia and Sickle cell traits. Primer-mediated enzymatic amplification of target sequences in genomic DNA followed by restriction endonuclease assay with an enzyme DdeI was carried out for the confirmation. RESULTS: Among 130 individuals, only 55.4% had basic knowledge about Sickle cell anemia. After screening for sickle cell anemia from 60 participants, 27 (45%) of them were found to be in the heterozygous state (carrier, Hb AS) and 28 (46.7%) were in the homozygous (normal, AA Hb) state with 5 (8.3%) having the diseased hemoglobin (Hb SS) variant of Sickle cell anemia. CONCLUSIONS: This study demonstrated a high prevalence of Sickle cell anemia and Sickle cell traits in the Tharu community. This study may be beneficial for concerned personnel policymakers to reduce sickle cell cases by improving genetic literacy among the Tharu community.

Glucose 6 phosphate dehydrogenase deficiency and hemoglobinopathy in South Western Region Nepal: a boon or burden.

OBJECTIVES: The study was carried out to optimize the phenotypic method to characterize the sickle cell trait (SCT), sickle cell anemia (SCA), and ß-thalassemia (ß-TT) suspected sample from tharu community of South Western province-5, Nepal. SCT and SCA were further evaluated by genotypic method employing amplification refractory mutation system (ARMS PCR). Moreover, Glucose 6 phosphate dehydrogenase (G6PD) was estimated in those hemoglobinopathy to observe its prevalence. The accurate and reliable method can play an important role in reduction of morbidity and mortality rate. RESULTS: The 100 suspected cases were subjected to phenotypic method adopting cellulose acetate electrophoresis and genotypic method using ARMS PCR which portraits (5%) SCA positive test showing HBS/HBS, (38%) SCT positive trait HBA/HBS and (36%) cases normal HBA/HBA. ß-TT (21%) cases were confirmed by electropherogram. G6PD deficiency was observed in (40%) of SCA, (18.4%) of SCT, (4.8%) of ß-TT and (2.8%) in normal cases. Increased G6PD were developed only in SCT (5.3%) and ß-TT (4.8%). The study highlighted sickle cell disorder (SCD) and ß-TT as the most common hemoglobinopathy coexisting with G6PD deficiency. Though hemoglobinopathy sometime could be protective in malaria but G6PD deficiency can cause massive hemolysis which may exacerbate the condition.

Battle between Host Immune Cellular Responses and HCMV Immune Evasion.

Human cytomegalovirus (HCMV) is ubiquitously prevalent. HCMV infection is typically asymptomatic and controlled by the immune system in healthy individuals, yet HCMV can be severely pathogenic for the fetus during pregnancy and in immunocompromised persons, such as transplant recipients or HIV infected patients. HCMV has co-evolved with the hosts, developed strategies to hide from immune effector cells and to successfully survive in the human organism. One strategy for evading or delaying the immune response is maintenance of the viral genome to establish the phase of latency. Furthermore, HCMV immune evasion involves the downregulation of human leukocyte antigens (HLA)-Ia molecules to hide infected cells from T-cell recognition. HCMV expresses several proteins that are described for downregulation of the HLA class I pathway via various mechanisms. Here, we review the wide range of immune evasion mechanisms of HCMV. Understanding the mechanisms of HCMV immune evasion will contribute to the development of new customized therapeutic strategies against the virus.

The polymorphism at residue 156 determines the HLA-B*35 restricted peptide repertoire during HCMV infection.

Peptide selection in infected cells is not fully understood yet, but several indications point to the fact that there are differences to uninfected cells, especially in productive HCMV infection, since HCMV evolved various strategies to disable the hosts immune system, including presentation of peptide-HLA complexes to immune effector cells. Therefore, peptide predictions for specific HLA alleles are limited in these cases and the naturally presented peptide repertoire of HCMV-infected cells is of major interest to optimize adoptive T cell therapies. The allotypes HLA-B*35:01 and B*35:08 differ at a single amino acid at position 156 and have been described to differ in their peptide features and in their association with the peptide loading complex. Virus specific T cells recognizing the allelic pHLA-B*35 complexes could be detected, indicating a significant role of this HLA subtypes in viral immunity. However, naturally selected and presented viral peptides have not been described so far. In this study, we analyzed the peptide binding repertoire for HLA-B*35:01 and HLA-B*35:08 in HCMV-infected cells. The isolated peptides from both allelic subtypes were of extraordinary length, however differed in their features, origin, and sequence. For these HCMV-originated peptides, no overlap in the peptide repertoire could be observed between the two allelic subtypes. These findings reveal the discrepancies between predicted and naturally presented immunogenic epitopes and support the need of comprehensive peptide recruitment data for personalized and effective cellular therapies.

Understanding the obstacle of incompatibility at residue 156 within HLA-B*35 subtypes.

Defining permissive and non-permissive mismatches for transplantation is a demanding challenge. Single mismatches at amino acid (AA) position 156 of human leucocyte antigen (HLA) class I have been described to alter the peptide motif, repertoire, or mode of peptide loading through differential interaction with the peptide-loading complex. Hence, a single mismatch can tip the balance and trigger an immunological reaction. HLA-B*35 subtypes have been described to evade the loading complex, 156 mismatch distinguishing B*35:01 and B*35:08 changes the binding groove sufficiently to alter the sequence features of the selected peptide repertoire. To understand the functional influences of residue 156 in B*35 variants, we analyzed the peptide binding profiles of HLA-B*35:01(156Leu), B*35:08(156Arg) and B*35:62(156Trp). The glycoprotein tapasin represents a target for immune evasions and functions within the multimeric peptide-loading complex to stabilize empty class I molecules and promote acquisition of high-affinity peptides. All three B*35 subtypes showed a tapasin-independent mode of peptide acquisition. HLA-B*35-restricted peptides of low- and high-binding affinities were recovered in the presence and absence of tapasin and subsequently sequenced utilizing mass spectrometry. The peptides derived from B*35 variants differ substantially in their features dependent on their mode of recruitment; all peptides were preferentially anchored by Pro at p2 and Tyr, Phe, Leu, or Lys at pΩ. However, the Trp at residue 156 altered the p2 motif to an Ala and restricted the pΩ to a Trp. Our results highlight the importance of understanding the impact of key micropolymorphism and how a single AA mismatch orchestrates the neighboring AAs.