PNNL

Abstract

Project final report Executive summary of the final project report outlines the major results achieved throughout the project performance. Detailed results and discussions have been presented in the eight quarterly reports. Introduction: Among pandemic-prone diseases, viral diseases—specifically influenza—have a significant, if not leading position. The prospect of influenza pandemic generates immediate alarm around the world. Far more contagious than most infections, it is spread by coughing and sneezing, and transmissible within an incubation period too short to allow for contact tracing and isolation. For these reasons, pandemic influenza would have devastating consequences. If a fully transmissible pandemic virus emerged, the spread of the disease could not be prevented. Development of strategies for mitigating the severity of a new influenza pandemic is now a top global public health priority. Anti-influenza vaccine is a major tool to protect the population or—at minimum— to ease symptoms in infected people. However, anti-flu vaccine is of moderate to low effectiveness for the groups most susceptible to the influenza virus: infants, adults above 65 years of age, and immune compromised people. In addition, the capacity to produce effective anti- influenza vaccine on a timely basis is problematic due to frequent mutations in influenza-causing viruses and the appearance of new viruses. Therefore, the world-class pharmacological strategies for dealing with the influenza pandemic are now based on antiviral drugs. To date, there are only five well-established anti-influenza drugs commercially available. However, recent studies have demonstrated that even Tamiflu—a champion therapy against influenza—is effective only in about 45-50% cases, and only if administered within the first 24-48 hours post infection. Tamiflu and the other four drugs may reduce the duration of flu symptoms but do not reduce the complications of flu, like pneumonia or hospitalizations, and are not confirmed to reduce transmission of the virus. Moreover, all current anti-flu drugs cause mild to severe side effects. In addition, different subtypes of the influenza virus have already shown the ability to become resistant to existing drugs such as Amantadine, and to the first line state-of-the-art Tamiflu. In fact, H1N1 influenza viruses contain a mutation conferring resistance to Tamiflu—one of the most common resistance mutations seen in treated patients since 2004—which has now circled the globe. This leaves a void in the ability to treat patients at the highest risk. Among the other anti-influenza drugs currently under development short interfering siRNAs seem to be very hopeful. Ribonucleic acid interference (RNAi) exploits an ancient part of the immune system that protects plants and animals against invaders by the depletion of viral genomic RNA targets in a sequence specific manner by making use of small interfering RNAs (siRNAs)]. Natural mechanism of siRNAs generation within a host cells can be bypassed by the use of synthetic RNA duplexes comprising of 19 nucleotide duplexes. The siRNA duplex comprised of a sense strand homologues to the target and an antisense strand that binds to the target mRNA. One of the major advantages of siRNA-based therapeutics in a pandemic influenza situation is that the design of specific siRNAs only requires knowledge of the circulating viruses’ gene sequence, and the siRNAs synthesis can be achieved within a short period of time (as compared to at least six months required for new vaccine production). Although specificity and tissue delivery remain major bottlenecks in the clinical applications of exogenous synthetic RNAi in general, intranasal application of siRNA against respiratory