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Early Trial Finds Vaccine Booster Covers Pandemic Flu Types

Nurse administering nasal vaccine


30 January 2014. An early-stage clinical trial shows an RNA agent being developed by Hemispherx Biopharma in Philadelphia extends the effectiveness of the standard nasal flu vaccine to cover pandemic influenza strains, like those found in Pacific Rim countries. Results of the trial were presented yesterday at a meeting of the American Society for Microbiology and at a press conference today in Washington, D.C.

Pandemic flu viruses are a public health concern worldwide, because of their ability to be spread easily from one person to another. In recent years, some of those viruses mutated from birds, including the avian strains H5N1 and H7N9, which was first reported in China in March of 2013.

Seasonal flu vaccines are formulated each year to cover the three or four most likely viruses to affect public health. This season, the vaccines offered as an injection or nasal spray, cover two influenza A strains — H1N1 and H3N2 — and one or both of two influenza B viruses. Seasonal flu vaccines, however, need to be produced well in advance of the flu season, which makes them ineffective against new strains that may threaten later on, such as the more recent pandemic strains.

Hemispherx is developing an synthetic double-stranded RNA compound called rintatolimod — brand-named Ampligen — that the company says has potential for treating various viral diseases, including cancer.  Ampligen works by stimulating microbial-sensing proteins called toll-like receptors that function as first-responders to infections.

The compound is being tested in clinical trials, either alone or in combination with other drugs, as a treatment for chronic fatigue syndrome, HIV, hepatitis B, renal cell carcinoma and malignant melanoma. Studies in Japan found mice given a combination of nasal flu vaccine and Ampligen developed an immune response to the H5N1 avian flu strain, suggesting its potential as a flu vaccine booster for humans.

The new clinical trial tested the safety of Ampligen in combination with the FluMist nasal spray form of seasonal flu vaccine, made by the MedImmune division of AstraZeneca. FluMist is a live attenuated vaccine that covers all four of the strains targeted in the 2013-2014 season, and is recommended in the U.S. for children age 2 and higher, and adults through age 49.

Hemispherx, with colleagues from University of Alabama in Birmingham, tested Ampligen with FluMist, because the antigens affected by Ampligen reside in mucous membranes of the nose and mouth. The research team asked 12 healthy Birmingham undergraduates to take three courses of a FluMist vaccine, followed three days later by a dose of Ampligen, ranging from 50 to 500 micrograms. The second and third vaccines were administered 28 and 56 days respectively after the first vaccine.

The researchers measured the immune response by the presence of immunoglobulins or antibodies in the blood. The tests looked specifically for the four antibodies corresponding to the A and B strains of flu in the FluMist vaccine. The tests also looked for antibodies generated to fight three pandemic flu strains:

– H5N1 that appeared in Vietnam in 2004 and Indonesia in 2005
– H7N9 that appeared in China in 2013
H7N3 that appeared among poultry processors in Jalisco, Mexico in 2012

The researchers found the addition of Ampligen doubled or quadrupled the number of antibodies against at least one of the four FluMist strains in 11 of the 12 trial participants, with 9 of the 12 participants exhibiting an 8-fold increase in at least one of the strains. In addition, 8 of the 12 participants showed double or quadruple the number of antibodies against at least one of the pandemic flu strains, with 6 of the 12 participants showing an 8-fold increase in antibodies. The research team reports participants receiving the smallest — 50 microgram — dose showed the greatest amount of immune response.

The safety tests indicate the combination of vaccine and Ampligen are generally well-tolerated, with largely mild adverse reactions, such as headaches and stuffy or runny noses. Most of the adverse reactions, say the researchers, occurred from the FluMist, not the Ampligen.

The next step in the clinical trial, says the company, is an intermediate-stage study that expands the number of participants to 60, and tests the combination of vaccine and Ampligen against a placebo.

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