Flu virus mutations are big concern for H1N1 experts

By Angela Mulholland, CTV.ca News

While fears about the H1N1 virus that we used to call swine flu are abating somewhat, virologists say we shouldn't let our guard down yet. The virus could undergo genetic changes and perhaps even return with a vengeance in the fall.

Influenza viruses are notorious for their ability to mutate. No one can predict what this virus will do, but we can look to past pandemic-type strains for guidance.

The 1918 Spanish flu first emerged in early summer, then went quiet, only to cause a severe pandemic in the fall. The same pattern occurred in 1957 and 1968, when flu strains emerged first in Asia then re-emerged in North America and Europe in the fall, though with less virulence than the 1918 strain.

This H1N1 strain, too, could continue to evolve. So far, the Centers for Disease Control and Prevention says the virus does not have the markers for virulence that were seen in the 1918 virus. But there is still much to understand.

Virologists say this new virus is a bit of a "mutt," containing bits of a virus that appears to have mixed with another hybrid virus that contained swine, bird and human genes.

Scientists in Mexico, the United States and New Zealand have all mapped full sequences of the DNA taken from 34 virus samples, and posted them in an online public journal called Eurosurveillance.

They explain that influenza A is a virus with eight different segments. When two viruses co-infect the same cell, new viruses can be produced that contain segments from both parental strains

Researchers from the Center for Computational Biology and Bioinformatics at Columbia University and elsewhere announced this week they've found that six segments of the virus are related to swine viruses from North America and the other two are from swine viruses isolated in Europe/Asia.

Hybrid virus: Where and when did it originate?

This particular strain looks partly like another hybrid virus. That virus was a swine virus that acquired a little bit of avian genetic material and a little bit of human genetic material sometime in 1997. It has been circulating in pigs in North America since that time.

This new virus seems to have taken that hybrid and then acquired some genetic material from an influenza virus that's been seen in parts of Europe and Asia.

The analysis is important to learn where and how the virus originated. If researchers can sequence the virus' genomes regularly during an outbreak, they can see which genes are evolving. That way, if the virus changes to cause new symptoms in patients -- for example, suddenly causing diarrhea in all patients -- researchers can figure out which gene mutation is causing the change.

That will also allow scientists to create and adjust tools to fight the virus, such as vaccines and rapid diagnostic test kits.

Microbiologists use "polymerase chain reaction" tests to analyze flu viruses. The technique "amplifies" DNA, generating millions copies of a particular DNA sequence. First, the test determines if the virus is influenza A, then further tests identify its subtype.

In Canada, when a lab can't identify the subtype, it has to be sent on to the National Microbiology Laboratory in Winnipeg, which is the only lab in the country that can confirm this new strain of H1H1.

The hope is that a new, rapid PCR test can be developed to detect this specific H1N1 by looking for gene sequences that are unique to this virus.

That should mean that a testing process that can now take as many as five days could soon pick up this H1N1 in four to six hours.

A rapid test confirmation can be critical; if a patient needs the antiviral medication Tamiflu, they need to start treatment within 48 hours of symptom onset.

Hong Kong scientists hope to design a PCR kit within a matter of weeks.

Vaccine and antibodies

A vaccine could take much longer: as long as six months. But scientists think a new vaccine is needed because while previous vaccines contain protection against H1N1, it's not the correct subtype of H1N1.

As Mark von Itzstein, director of the Institute for Glycomics in Australia's Griffith University, told Reuters this week: "it only takes one amino acid change in the whole protein makeup of the virus to escape the vaccine."

Preliminary research suggests people 60 and older may already have some protection against the new swine flu, possibly because of vaccines they've received in the past.

Dr. Nancy Cox, the head of the influenza division at the U.S. Centers for Disease Control says work being done in the Atlanta labs shows older people have some antibodies that may offer protection against the swine H1N1 virus.

Cox says her team is seeing higher levels of antibodies against the virus in people starting at about age 50, but the rise is more noticeable in people 60 and older. She says the pattern of disease spread seems to support the idea, because most of the cases are in young people.