Researchers are on the verge of developing a universal vaccine that will provide immunity to all kinds of flu viruses:-
Like all professionals, medical researchers also have grand ambitions. One of the grandest of these ambitions is to find a universal vaccine for influenza. This disease kills about 5 lakh people worldwide every year. Its potential to wreak havoc is enormous, and the only way to stop this virus in its tracks is a universal vaccine. Such a vaccine could protect us from any kind of flu, whether serious or benign. Not long ago this was considered an impossible dream , but now scientists are inching closer to achieving this dream.
At least five research groups in the world — three in the US, one in Belgium and one in Israel — have developed a kind of universal flu vaccine, and they have either already started Phase I clinical trials or will start them this year. Initial results are good in all of them — patients seem to tolerate the low doses and develop an immune response. But the big test is to come in the next year or two, when the vaccine is given to a large population and tested for efficacy. If these vaccines are good enough to stop the disease, the days of global flu-related panic may be over in about five to seven years.
Making a vaccine against a virus is a trivial or an impossible exercise, depending on the nature of the virus. Some viruses are very stable over a long time, which means that they do not mutate quickly. This means that the proteins on their surface remain the same in all varieties, as in the case of small pox, which makes it possible to develop a vaccine that remains effective over long periods. The influenza virus, on the other hand, keeps mutating all the time. Most of the mutations are small, but occasionally they change in a significant way. In fact, even in seasonal flu, the vaccine does not afford full protection because there are different kinds of flu viruses and it is not possible to design a vaccine for all of them.
Periodically, the influenza virus acquires genes from flu viruses that inhabit other animals. This is how the recent swine flu emerged. This mixing of genes makes it literally impossible to design vaccines as it is impossible to predict how and when the genes will mix and in what combination.
However, scientists had not given up trying to develop a universal flu vaccine. And now there are signs that some of them will succeed.
At the Saint Louis University (SLU) in the US, like elsewhere, researchers looked for a portion of the virus that does not change even if the virus mutates. They did find such portions, called M2, on all flu viruses. This portion is involved in most of the universal vaccines under development. “All flu viruses will have an M2 portion,” says Donald Kennedy, professor of infectious diseases at the university. SLU had done Phase I clinical trials on 377 patients and found that it was tolerated well on low doses. People also developed antibodies at levels known to protect against viral infections.
This vaccine is designed to work against the so-called A strains of the influenza virus. It is the cause of two-thirds of all flu infections and all the pandemic cases. Of the other two viruses, the C type is rare and is not fatal and the B type does not cause global pandemics. The current swine flu is an A type flu, and so is the avian flu that periodically causes a pandemic scare.
At the University of Ghent in Belgium, scientist Walter Fiers also used a similar approach to develop a universal vaccine. This vaccine was licensed to the British-American company Acambis, and Phase I clinical trials are over. Acambis had also tested whether vaccinated ferrets could survive an infection from a highly lethal avian flu strain. About 70 per cent of the vaccinated animals survived, while all the placebo controls (ferrets that were administered dummy vaccines) died.
While these two groups (from the US and Belgium) — and a few others — use the M2 portion of the virus, a private company in Israel is using a combination of regions in the virus that remain the same in all types. This company, BiondVax Pharmaceuticals Ltd, licensed the technology from the Weizmann Institute in Tel Aviv. It is using a portion of the virus called M1 in combination with other portions. “It is based on peptides that are conserved in the vast majority of the flu strains,” says Ron Babecoff, president and CEO of BiondVax. A single vaccination is supposed to provide immunity for several years for many kinds of flu viruses.
Some viruses keep mutating all the time, but while most mutations are small, occasionally they change significantly.
BiondVax has tested the vaccine in animals. In a humanised mouse — a genetically engineered mouse that carries human genes — the vaccine was found to be 95 per cent effective, a level that is good enough for any vaccine. BiondVax has government approval to start human trials, and will do so this month. It is also working on what it calls the second generation universal flu vaccine.
But, at the moment, let us watch the progress of the first one.
Sources: The Telegraph (Kolkata, India)