Non-overlapping epitopic regions recognized by the two mAbs, E8G9 and

Non-overlapping epitopic regions recognized by the two mAbs, E8G9 and D2H3. To delineate the specific epitopic regions, western blot analysis was carried out using different overlapping fragments of HCV E2 protein (Fig. 4A), expressed in E. coli. The entire E2 coding region of HCV was divided into five overlapping gene fragments (Fig. 4A), which were amplified, cloned and expressed in E. coli. All the five purified protein fragments were analyzed by western blot analysis with E8G9 and D2H3 mAbs. It was seen that E8G9 reacted with region 3 (555 to 646 aa) and region 4 (596 to 699 aa) whereas mAb D2H3 reacted with region 4 only (Fig. 4B). Results indicated that region 3 which is present between amino acids 555 to 646 may be involved in the inhibition of HCV-LP binding to Huh 7 cells. The epitope of mAb H1H10, could not be delineated because it recognizes a conformational epitope and thus fails to react in western blot analysis.DiscussionIn this work, we have reported for the first time the generation of recombinant HCV-LP for genotype 3a, which is prevalent in India. We have also generated the HCV-LP corresponding togenotype 1b prevalent worldwide for comparison. The HCV-LP corresponding to 1b appears to be polygonal in shape and 40 to 60 nm in size as reported earlier, whereas HCV-LP of 3a was found to be approximately 35?5 nm in size. Thus, structurally and morphologically the VLPs were distinct. This could be due to differences in the sequences and conformation of the envelop protein of the two 1662274 different genotypes. Also it is possible that the amount of E2 protein incorporated in virus like particle could be relatively more in case of genotype 1b. The HCV-LP genotype 3a showed almost 80 binding to Huh 7 cells, whereas genotype 1b HCV-LP showed approximately 70 binding suggesting differential affinity of the HCV-LPs towards liver cells. The binding of HCV-LP to the Huh7 cells was maximum at 4h of incubation and after which there was decrease in fluorescence. It is possible that after 4h of incubation, the HCV-LPs enter into the cells by receptor mediated endocytosis. Interestingly, both genotype 3a and genotype 1b HCV-LPs showed similar results. There is a cascade of events which enable the attachment and entry of HCV into permissive cells. The mAbs E8G9 and D2H3 are probably against the HCV-LP envelope protein region involved in binding to any one of the several set of cellular receptor proteins. Since the epitope for 1662274 different genotypes. Also it is possible that the amount of E2 protein incorporated in virus like particle could be relatively more in case of genotype 1b. The HCV-LP genotype 3a showed almost 80 binding to Huh 7 cells, whereas genotype 1b HCV-LP showed approximately 70 binding suggesting differential affinity of the HCV-LPs towards liver cells. The binding of HCV-LP to the Huh7 cells was maximum at 4h of incubation and after which there was decrease in fluorescence. It is possible that after 4h of incubation, the HCV-LPs enter into the cells by receptor mediated endocytosis. Interestingly, both genotype 3a and genotype 1b HCV-LPs showed similar results. There is a cascade of events which enable the attachment and entry of HCV into permissive cells. The mAbs E8G9 and D2H3 are probably against the HCV-LP envelope protein region involved in binding to any one of the several set of cellular receptor proteins. Since the epitope for 1516647 the E8G9 was putatively mapped to 596?46 which is probably structurally close to the sites of the E2 protein critical for CD81 receptor binding (,420, 527, 529, 530, 535) [33,34] it might have been more effective in prevention of the virus binding. The same E8G9 mAb also showed better inhibition (,66 ) of virus entry in the HCV cell culture system and the mAb H1H10 showed only marginal inhibition (,30 ). Perhaps the epitope for H1H10 is mapped to a distant location from the receptor binding domains of E2 protein. Further, mAbs D2H3, G2C7 and E1B11 didn’t show significant inhibition of binding of HCV-LP to Huh 7 cells. The epitope for D2H3 has been mapped in the region 4 (596?99 aa of E2 protein), which might be far from receptor binding sites. The epitopes for H1H10, G2C7 and E1B11 could not be mapped by western blot analysis, possibly due to the fact that the mAbs are conformation specific. Since IgG from culture supernatant of hybridoma cells were used for the ELISA assay, it is possible that the E8G9 and H1H10 speci.