New Experimental Vaccine Against Avian Influenza

A newly developed experimental vaccine was found to block the deadly H5N1 avian influenza virus, say researchers. It is also effective against the H9 subtype of avian influenza.

The strength of the new vaccine is that it uses attenuated, rather than "killed" virus. (Killed viruses are broken apart with chemicals or heat, and they are used because they are safer than attenuated viruses.)

Avian Influenza / Bird Flu-Causes-Symptoms-Treatment- FAQs
Bird flu (avian influenza/avian flu) is a disease caused by an influenza virus (H5N1) that primarily affects birds but can infect humans also.

Killed virus vaccines against avian influenza are injected into the bloodstream, whereas this vaccine is given via nasal spray, thus mimicking the natural infection process, stimulating a stronger immune response.

The danger of current attenuated virus vaccines is that they might exchange dangerous genetic material with garden variety influenza viruses of the sort that strike annually, potentially rendering a lethal but very hard to transmit influenza virus, such as H5, easily transmissible among humans.

To mitigate those dangers, the study authors, led by Daniel Perez of the University of Maryland, came up with an ingenious design.

Quiz on Flu
Influenza (or rather, the flu) is a cold weather infectious condition that affects the young and old alike. Though most reported cases are mild, the flu can sometimes cause severe and life-threatening complications in both children and adults, thanks to wrong medications and improper vaccinations. Learn more about the disease from our Flu Quiz and guard yourself and your family from a possible infection.

Influenza viruses carry their genetic material in eight "segments," coauthor and University of Maryland colleague Troy Sutton said.

When viruses reassort, they exchange segments. But each segment is unique, all eight are needed, and the viruses are unfit if they contain more than eight segments.

Role of Climate in Influenza Transmission Revealed
According to an epidemiological study led by researchers, two types of environmental conditions cold-dry and humid-rainy are associated with seasonal influenza epidemics.

The vaccine is based on an attenuated version of the H9 virus, with an H5 gene added into one of the H9 virus' segments, to confer immunity to the H5 virus.

Segment 8, which is composed of the so-called NS1 and NS2 genes, was split apart, and the NS2 gene was moved into segment 2, adjacent to the polymerase gene, which copies the virus' genetic material during replication.

UCLA Researchers Developing Ways to Predict Future Bird Flu Outbreaks
Researchers at University of California Los Angeles are currently busy in developing new ways through which they can predict where the next bird flu outbreak can emerge.

Placing NS2 next to the polymerase gene slowed its function, interfering with the virus' replication. That makes the vaccine safer.

The next step was to engineer the H5 gene into the vaccine. It was inserted into segment 8, where the NS2 gene had been.

Another aspect of the new vaccine's design makes it safer still, by rendering successful reassortment less likely. Both NS1 and NS2 are needed for viral replication.

Since the two genes are now separated into different segments, any reassortment will have to include both segments, instead of just segment 8, in order for a reassortant virus to be viable. This greatly reduced the probability of successful reassortment.

The research is published online ahead of print in the Journal of Virology.

Source-ANI