Analysis of helicase domain mutations in the hepatitis E virus derived from patients with fulminant hepatic failure: Effects on enzymatic activities and virus replication

作者：Devhare Pradip; Sharma Kavyanjali; Mhaindarkar Vaibhav; Arankalle Vidya; Lole Kavita^*

来源：Virus Research, 2014, 184: 103-110.

DOI：10.1016/j.virusres.2014.02.018

• Hepatitis E virus
• Helicase
• Mutations
• Fulminant hepatic failure

Fulminant hepatic failure (FHF) is the severe form of hepatitis E virus infection. Virus sequence analyses from severe cases have shown presence of unique and highly conserved mutations in the helicase domain of genotype 1,3 and 4 viruses. We evaluated role of two amino acid replacements (L111 0F) and (VI 1201); found to be frequent in genotype 1 FHF-E viruses from India. Three mutant helicase proteins (two with single point mutations and one with dual mutations) were expressed in Escherichia coli and evaluated for their ATPase and RNA unwinding activities. Both L11 10F and V11201 helicase mutants showed marginal decrease in ATPase activity, while L1110F/V11201 dual mutant showed normal ATPase activity. All three mutants proteins showed RNA unwinding activities comparable to wild type protein. Corresponding mutations were made in the helicase domain of HEV RLuc replicon and replication efficiencies were tested in the S10-3 (Huh 7) cells. The mutant replicon V11201 showed lower replication as compared to L11 10F and L1110F/V1120I mutants. However, all three replicon mutants showed lower replication efficiencies as compared to the wild type replicon. Walker A and Walker B motif mutant HEV replicons were unable to replicate indicating essential role of the virus encoded helicase domain during HEV replication. FHFE associated helicase mutations resulted in only marginal decrease in the virus replication suggesting alternate function/s of the helicase protein. Mutations in the helicase domain of FHF-E viruses may be responsible for changing virus or host-virus protein protein interactions, causing alterations in the host responses, eventually leading to more severe disease manifestations.

• 出版日期2014-5-12