Press Release

NeuGene Antisense Efficacy Against Influenza Strains Reported at the International Conference on Antiviral Research

PORTLAND, Ore.--(BUSINESS WIRE)--May 9, 2006--AVI BioPharma, Inc. (Nasdaq:AVII), today presented positive preclinical data, resulting from preclinical experiments targeting multiple strains of influenza with NEUGENE(R) antisense compounds, at the 19th International Conference on Antiviral Research. The presentation, titled "Inhibition of Multiple Influenza A Subtypes with Antisense Phosphorodiamidate Morpholino Oligomers," detailed confirmatory studies by three independent laboratories, as reported previously, and presented new toxicology, pharmacokinetic and preliminary animal efficacy data.

Efficacy data observed in cell culture with the H1N1 strain, previously reported by Drs. Jianzhu and Chen Qin Ge at Massachusetts Institute of Technology, has been confirmed by Dr. P. Puthavathana at Mahidol University in Bangkok, Thailand, against an H5N1 viral isolate; by Dr. Darwyn Kobasa at the Public Health Agency of Canada in Winnipeg, Manitoba, against both the H1N1 and H3N2 strains; and by Dr. Manoj Pastey at Oregon State University in Corvallis, Ore., against the H7N7 and H3N8 strains.

These researchers have now completed toxicology and pharmacokinetic (PK) studies in rats, as well as preliminary efficacy studies in the first of several planned animal models. The toxicology and PK studies exhibited both a favorable safety profile and plasma clearance half-life, boding well for a possible future IND filing and clinical trial. In the initial animal studies using the fertilized egg model, low doses of a single NEUGENE antisense agent protected approximately half the animals from a lethal challenge with H1N1. Additional dose escalation studies with NEUGENE antisense agents are underway, and studies to evaluate protection of mice and ferrets against both H1N1 and H5N1 strains are planned to support an Investigational New Drug (IND) application.

"We believe that a single NEUGENE drug could be effective against most influenza subtypes," said Patrick L. Iversen, Ph.D., senior vice president of research and development at AVI. "By targeting regions of the viral genetic code that are common to all influenza A subtypes, we expect that our NEUGENE drugs will be effective against avian flu and the far more common influenza A viruses, which kill an average of 35,000 Americans every year."

AVI's NEUGENE antisense drug development program against the influenza A virus targets genetic regions of the virus that are highly conserved across six viral subtypes that cause human disease. These include three subtypes that caused pandemics in the 20th century -- the 1918 Spanish flu (H1N1), the 1957 Asian flu (H2N2) and the 1968 Hong Kong flu (H3N2) -- and three subtypes of avian flu that have been reported to cause disease in humans (H5N1, H7N7 and H9N2).

AVI's Antiviral Program

AVI's proprietary NEUGENE antisense drug candidates have demonstrated efficacy in preclinical studies against SARS coronavirus, West Nile virus (WNV), hepatitis C virus (HCV), dengue virus, Ebola virus and Marburg virus. AVI has filed IND applications with the U.S. Food and Drug Administration and has ongoing clinical trials in WNV and HCV.

Showing how versatile NEUGENE drugs can be across viral subtypes, AVI demonstrated in its collaboration with the Centers for Disease Control and Prevention that NEUGENE agents are efficacious against all four immunologically distinct subtypes of the dengue virus. This outcome was achieved by targeting a highly conserved region of the dengue viral genetic code. In collaborative work with the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID) targeting the Ebola virus, NEUGENE drugs protected three animal species from lethal challenges with this virus (see PloS Pathog 2(1): e1). Additional clinical development efforts targeting dengue virus and Ebola virus are planned for 2006.

The speed with which effective NEUGENE drugs can be designed and manufactured exceeds any other modern drug development time frame. For example, NEUGENE compounds targeting SARS, WNV and Ebola were developed within days to weeks of obtaining the appropriate genetic sequences for the viruses.

AVI's Clinical Experience

AVI's NEUGENE antisense drugs have a well-defined safety record in human clinical trials. More than 300 patients have been dosed with NEUGENE drug candidates targeting host and viral gene targets in 12 clinical studies under multiple INDs. Five routes of administration have been employed in AVI's clinical studies, and doses up to 450 mg have been administered without a single drug-related serious adverse event. The combination of AVI's NEUGENE chemistry with conserved viral targets that are not expressed in the human genome makes a strong case for the potential for success in the development of candidates to address influenza, including the possible emergence of a transmittable avian flu.

About Influenza A Viruses

Influenza, or flu, is a contagious respiratory illness caused by influenza viruses. On average 5 percent to 20 percent of the U.S. population is infected with the flu each year. Influenza A virus is an enveloped negative-strand RNA virus, with eight genome segments that code for 10 proteins. Influenza strains are subtyped according to the antigenic and genetic nature of their surface glycoproteins: hemagglutinin (HA or H) and neuraminidase (NA or N). Fifteen H and nine N subtypes have been identified, with three associated with widespread human disease (H1N1, H2N2 and H3N2). In addition, several subtypes of avian influenza virus -- H5N1, H7N7 and H9N2 -- can infect and cause disease in humans.

The current influenza pandemic in birds throughout Asia, Eastern Europe and Turkey is caused by the H5N1 subtype. It is thought that co-infection of humans or certain animals (such as pigs) with both H1N1 and H5N1 can lead to a reassortment or recombination of viral particles, resulting in the emergence of a virus with dangerous public health properties, namely one to which the human population has no natural immunity and which has the ability to spread easily from person to person. It is believed that emergence of avian flu by this general mechanism may have led to the worldwide pandemics of 1918, 1957 and 1968.

About AVI BioPharma

AVI BioPharma develops therapeutic products for the treatment of life-threatening diseases using third-generation NEUGENE antisense drugs. AVI's lead NEUGENE antisense compound is designed to target cell proliferation disorders, including cardiovascular restenosis, cancer and polycystic kidney disease. In addition to targeting specific genes in the body, AVI's antiviral program uses NEUGENE antisense compounds to combat disease by targeting single-stranded RNA viruses, including West Nile virus, hepatitis C virus, dengue virus, Ebola virus and influenza A virus. AVI has introduced a NEUGENE-based exon-skipping technology called ESPRIT therapy. More information about AVI is available on the company's Web site at www.avibio.com.

"Safe Harbor" Statement under the Private Securities Litigation Reform Act of 1995: The statements that are not historical facts contained in this release are forward-looking statements that involve risks and uncertainties, including, but not limited to, the results of research and development efforts, the results of preclinical and clinical testing, the effect of regulation by the FDA and other agencies, the impact of competitive products, product development, commercialization and technological difficulties, and other risks detailed in the company's Securities and Exchange Commission filings.

    CONTACT: AVI BioPharma, Inc.
             Michael Hubbard, 503-227-0554
             hubbard@avibio.com
             or
             Lippert/Heilshorn & Associates Inc.
             Investor Contact
             Jody Cain, 310-691-7100
             jcain@lhai.com
             or
             Waggener Edstrom Worldwide Bioscience
             and Healthcare Practice
             Press Contact
             Andie Long, 202-326-0791
             andreal@waggeneredstrom.com

    SOURCE: AVI BioPharma, Inc.