Antigenic Variants of Influenza A/H3N2 Viruses
Posted on 09/21/2005 2:27:51 PM PDT by neverdem
Rome, Sept. 21 - Just as governments around the world are stockpiling millions of doses of flu vaccine and antiviral drugs in anticipation of a potential influenza pandemic, two new research papers published today have found that such treatments are far less effective than previously thought.
"The studies published today reinforce the shortcomings of our efforts to control influenza," wrote Dr. Guan Yi, a virologist at the University of Hong Kong, in an editorial that accompanied the papers. The two studies were published early online by the British medical journal, the Lancet, because of their implications for the upcoming flu season.
In one paper, international researchers analyzed all the data from patient studies on the flu vaccine performed worldwide in the past 37 years and discovered that vaccines showed at best a "modest" ability to prevent influenza or its complications in elderly people.
"The runaway 100 percent effectiveness that's touted by proponents was nowhere to be seen," said Tom Jefferson, a Rome-based researcher with the Cochrane Vaccine Fields project, an international consortium of scientists who perform systematic reviews of research data.
"There is a wild overestimation of the impact of these vaccines in the community," Dr. Jefferson said. "In the case of a pandemic, we are unsure from the data whether these vaccines would work on the elderly."
In the second paper, researchers from the Centers for Disease Control found that influenza viruses, particularly those from the dreaded bird flu strain, had developed high rates of resistance to older and cheaper antiviral drugs - rates that have escalated rapidly since 2003, particularly in Asia.
(Excerpt) Read more at nytimes.com ...
Uh, I thought you just did. ;^)
Someone correct me if I'm wrong, but isn't the recommended annual flu shot a combination of three inactivated influenza viral types thought to be most likely coming from the Far East each year, and isn't the HxNx nomenclature for for Influenza Type A subtypes?
Do Influenza Types B or C have variations of the Hemagglutinin or Neuraminidase enzymes on their capsid coats? I'm just a humble FP.
Antigenic Variants of Influenza A/H3N2 Viruses
Boy that post was screwed up.
There's always a chance to redeem oneself. What's the logic to the nomenclature?
Well it supposed to convey some of the distance variations in the amino acid sequences in the H3N2 virus.
Let me hazard a guess. I'm not a virologist. The names represent the place and year that various single nucleotide polymorphisms, aka as snips which caused illness, were sampled and which were designated variants of the Influenza A H3N2 subtype.
When I read 100% efectiveness I KNEW I was reading the rantings of an imbicle. I read no further.
BTW, I've never gotten the flu shot, and had the flu only once.
What does that prove? Simply this: "I've never gotten the flu shot, and had the flu only once." No more, no less.
Influenza viruses belong to the orthomyxovirus family and consist of types A, B, and C. These medium-sized (80 to 120 nm), enveloped, single-stranded RNA viruses contain eight gene segments (seven for influenza C).
The segmented nature of the genome allows reassortment of RNA segments between two influenza viruses during dual infection and facilitates antigenic variation.
Surface glycoprotein spikes possess either hemagglutinin or neuraminidase activity.
Hemagglutinin mediates cell attachment and fusion of virus and cell membranes. By cleaving terminal sialic acid residues and destroying the receptors recognized by hemagglutinin, neuraminidase promotes release of virus from infected cells and spread within the respiratory tract.
Influenza C viruses have seven gene segments and lack a neuraminidase.
The surface glycoproteins induce host humoral and cellular immune responses and are responsible for the changing antigenicity of influenza viruses.
Two major types of antigenic change can occur: drift and shift. Antigenic drift refers to relatively minor changes in hemagglutinin and, less often, neuraminidase antigenicity that occur frequently (usually every few years) and sequentially in the setting of selective immunologic pressure in the population. Drift results from point mutations of the corresponding RNA segment.
Antigenic shift occurs only in influenza A viruses and results from acquisition of a new gene segment for hemagglutinin with or without one for neuraminidase.
This may occur through genetic reassortment during dual infections with human and animal influenza type A viruses; by the reintroduction of a virus that has not circulated recently in the human population; or by direct transmission to humans of an animal influenza virus that is capable of efficient human-to-human transmission.
MA
Done
So much more effective than the shots. I carry a little bottle of that alcohol hand rinse stuff in my car, and just do a quick wash when I come in from the grocery store or mall. No flu.
Thanks for the information. Let me see if I understand it correctly.
It appears that genetic drift is the result of single nucleotide polymorphisms, aka as snips.
Genetic shift is the result of recombination of genes during simultaneous infection by two different subtypes of influenza virus.
These phenomena are also not limited to influenza, but occurs with other viruses during replication.
Similar experience.
Was pressured by a collegue to get a flu shot, even though I am considered immune compromised.
Guess what?
Haven't gotten a shot since and will not.
I am no longer working in the field so I do not know what the current wisdom is, However, simply put, I have never believed that the manufacture of FLU vaccines is capable of keeping up with the flu's ability to mutate, or the speed at which new flu strains spread.
Wash your hands frequently and stay away from people who are to ignorant to home when they are sick.
JMNSHO, LOL
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