Avian Flu Medication Lost its Potency

H5N1 in a computer rendering of its protein shell.

Today the Swedish radio reported that in one year the most commonly used medication against influenza viruses; Tamiflu the medication each and everyone stockpiled in 2005 and actually one of the few medications that was somewhat useful in the treatment of bird flu infected humans have lost a lot of its potency because the flu strains has become resistant to it.

This is a problematic development because there are not many other medications that have effect on this dangerous illness and the scare that it would combine with an ordinary flu to form a ”super flu” for which we do not have a treatment has been actualized again because of this.

In fact several countries who stockpiled Tamiflu are now just going to destroy it – basically incinerate it. In many cases this is a result of decision makers not listening to the scientists telling them that Tamiflu would probably not be the best way to spend the resources to combat avian flu virus.

Last time when the bird flu was on everybody’s lips (figuratively) many voices where heard crying out that the government should start stockpiling Tamiflu, licencse it and start whole new factories to make extremely large quantities of such medications in order to have ”enough medication for everyon”  in the event that bird flu should become the pandemic that some thought it might become.

The scientists at the time tried to explain that it was a bad use of resources for several reasons including the very true reason that the human version of the bird flu, the ”super flu” would be different from the bird flu virus in several ways and the Tamiflu medication may not have any effect at all on this form if it formed and in fact it was better to work from the other end with more research on bird flu itself and to prepare to find a more suitable medication tailored to the new flu when it emerged.

But this is very difficult to do unless you have an infected population to work from and to create a medication for an illness that does not exist is very difficult to not say rather impossible.

The Avian Flu virus have mutated into several strains since it was observed closely in 2005 and common antigens have been found but there is enough variation within the group of avian flu viruses that it is not possible to create a single ”strike all” medication and therefore stockpiling the Tamiflu is at best a waste of money.

Now we have observed strains that are resistant to the drug and therefore can not effectively be treated with it so if the resources had been spent on more and better research instead we might have had a broad spectrum antiviral agent or at least better anti-ful agents for the strains that are most likely to combine with a human flu and form a ”super flu” that we all dread.

This is from a post I wrote on the 13th of November in 2005 that explains more aboit the avian flu virus and why stockpiling Tamiflu is not the solution to the problem:

Several papers this morning carries the story that the Avian Flu virus have mutated. It is true, these types of viruses mutates all the time. It is still not the human transferably strain that the scientist are worried about, though the current mutation may make it easier to infect mammals.

The source is the net paper Vietnam Express that most people seem to quote in their articles. What has been found is that the virus from 24 different samples has been shown to produce antigens that could help the virus to infect humans or other mammals.

This type of mutation is normal for most influenza type viruses and it would be disingenous to think that the avian flu virus would not go through the same antigenic drift as any other virus would. This is a normal development of a virus and can produce new strains that are more or less aggressive to us humans.

Such mutations occur almost yearly in the influenza virus, and while the change might not be a major one (which would then be called an antigenic shift), they are sufficient to lessen your body’s ability to protect you with antibodies. For this reason, vaccination is required on a yearly basis, with the vaccine adjusted to the new antigen. In influenza, mutations happen frequently because the virus has no way of checking its RNA for errors.

An antigenic shift is what the scientist are worried about when it comes to the strain H5N1 of the avian influenza virus. This is what would could make it very contagious among humans. An antigenic shift s the process by which two different strains of influenza combine to form a new subtype having a mixture of the surface antigens of the two original strains. The term antigenic shift is specific to the influenza literature; in other viral systems, the same process is called reassortment or viral shift.

How many of you have seen the numbers H5N1 without having any idea what it is? Well it is not so difficult it is a way of telling the types of surface molecules on the virus. Flu strains are named after their types of hemagglutinin and neuraminidase surface proteins, so they will be called, for example, H3N2 for type-3 hemagglutinin and type-2 neuraminidase. If two different strains of influenza infect the same cell simultaneously, their protein capsids and lipid envelopes are removed, exposing their RNA, which is then transcribed to mRNA. The host cell then forms new viruses that combine antigens; for example, H3N2 and H5N1 can form H5N2 this way. Because the human immune system has difficulty recognizing the new influenza strain, it may be highly dangerous. Such combinations caused, for instance, the infamous Spanish Flu outbreak of 1918 which killed 40 million people worldwide. Influenza virus which have undergone antigenic shift have also gone on to cause the Asian Flu pandemic of 1957, the Hong Kong Flu pandemic of 1968, and the Swine Flu scare of 1976.

There are 16 different hemagglutinin subtypes and 9 different neuraminidase subtypes, all of which have been found among influenza A viruses in wild birds. Wild birds are the primary natural reservoir for all subtypes of influenza A viruses and are thought to be the source of influenza A viruses in all other animals. Most influenza viruses cause asymptomatic or mild infection in birds; however, the range of symptoms in birds varies greatly depending on the strain of virus. Infection with certain avian influenza A viruses (for example, some strains of H5 and H7 viruses) can cause widespread disease and death among some species of wild and especially domestic birds such as chickens and turkeys.

Pigs can be infected with both human and avian influenza viruses in addition to swine influenza viruses. Infected pigs get symptoms similar to humans, such as cough, fever, and runny nose. Because pigs are susceptible to avian, human and swine influenza viruses, they potentially may be infected with influenza viruses from different species (e.g., ducks and humans) at the same time. If this happens, it is possible for the genes of these viruses to mix and create a new virus.

For example, if a pig were infected with a human influenza virus and an avian influenza virus at the same time, the viruses could mix (reassort) and produce a new virus that had most of the genes from the human virus, but a hemagglutinin and/or neuraminidase from the avian virus. The resulting new virus would likely be able to infect humans and spread from person to person, but it would have surface proteins (hemagglutinin and/or neuraminidase) not previously seen in influenza viruses that infect humans. This type of major change in the influenza A viruses is known as antigenic shift. Antigenic shift results when a new influenza A subtype to which most people have little or no immune protection infects humans. If this new virus causes illness in people and can be transmitted easily from person to person, an influenza pandemic can occur.

In 2004, scientists pointed out that the avian influenza virus might undergo an antigenic shift with the human flu virus and cause a global influenza pandemic like the one in 1918.