Biomedical subjects

Abdullah Ely

Publications and source records attributed to Abdullah Ely.

3 recordsLinked to original sources

PubMed2007

Specific inhibition of HBV replication in vitro and in vivo with expressed long hairpin RNA.

Activating RNA interference to achieve specific gene silencing has shown promise for the development of RNA-based treatment of chronic hepatitis B virus (HBV) infection. To further this approach, we assessed the efficacy of expressed long hairpin RNAs (lhRNAs) that target the conserved HBx open reading frame of HBV. As substrates for Dicer, lhRNAs have the potential to generate multiple short interfering RNAs (siRNAs) to enable simultaneous targeting of different sites. Two U6 Pol III vectors were constructed that encode anti-HBV lhRNAs with a 62 base pair stem sequence containing multiple G:U pairings. Assessment in transfected cultured cells and also in vivo using the murine hydrodynamic injection model showed that one of the lhRNA vectors (lhRNA 1) diminished markers of virus replication by 70-90% without evidence of interferon response induction. Greatest silencing efficacy was observed for targets that are complementary to sequences located at the base of the hairpin stem and this correlated with a higher concentration of siRNAs derived from this region of the lhRNA. Although lhRNA 1 has the advantage of targeting a greater viral sequence, incomplete cellular processing may result in unequal silencing across the span of the viral target RNA.

Animals↗

PubMed2005

Effective inhibition of HBV replication in vivo by anti-HBx short hairpin RNAs.

Exploiting the RNA interference pathway has shown promise for developing novel and effective treatment of hepatitis B virus (HBV) infection. To advance this approach, we analyzed the antiviral efficacy of a panel of 10 Pol III U6 promoter-encoded short hairpin RNAs (shRNAs) that target conserved sequences of the oncogenic HBx open reading frame. To facilitate intracellular processing, the shRNAs included mismatches in the 25-bp stem region and a terminal loop of miRNA-23. Two shRNAs (shRNA 5 and shRNA 6) showed knockdown of HBV markers by 80-100% in transfected hepatocytes and also in a murine hydrodynamic injection model of HBV replication. Intracellular processing of hairpin RNA with the intended strand bias correlated with antiviral efficacy. Moreover, markers of HBV replication were inhibited without inducing genes associated with the nonspecific interferon response. To assess the antiviral efficacy of the shRNAs in a context that is similar to natural HBV infection, shRNA-encoding cassettes were tested against the virus in a HBV transgenic murine model. When delivered using recombinant adenovirus vectors, U6 shRNA 5 and U6 shRNA 6 mediated significant HBV knockdown. Collectively, these observations indicate that U6 shRNA 5 and U6 shRNA 6 are promising candidates for therapy of chronic HBV infection.

Adenoviridae↗

PubMed2005

Exploiting the RNA interference pathway to counter hepatitis B virus replication.

Chronic infection with hepatitis B virus (HBV) is endemic to sub-Saharan Africa and parts of Asia where persistence of the virus is commonly associated with complicating cirrhosis and hepatocellular carcinoma (HCC). Licensed therapies for HBV are partially effective in selected patients and development of novel treatments remains an important global medical objective. HBV has an unusually compact genome that restricts the ability of the virus to evade potentially therapeutic nucleic acid hybridization. Thus, exploiting the RNA interference (RNAi) pathway, which enables sequence-specific target RNA degradation using small interfering RNA (siRNA), is well suited to developing novel treatment for HBV infection. Several studies, both in vitro and in vivo, have demonstrated that HBV replication can be inhibited in transfected cells by synthetic siRNA duplexes and also Pol III-derived short hairpin RNA (shRNA) sequences. The effectiveness of anti-HBV sequences varies considerably, and is likely to result from differences in activation of the RNAi pathway by individual siRNA species. Exclusion of potentially toxic off-target effects and also development of efficient methods of hepatotropic nucleic acid delivery are important prerequisites before RNAi can be used successfully for anti-HBV treatment.

Gene Expression Regulation, Viral↗