Swine Flu Virus: A Fast Spreading Virus

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Swine Flu Virus:  A Fast-Spreading Virus




Guest:  Dr. Michael Schmidt – Basic Sciences/Microbiology & Immunology, MUSC

Host:  MUSC


MUSC:  Dr. Michael Schmidt is Professor of Microbiology and Immunology at the Medical University of South Carolina.  He shares the concerns of many about the swine influenza virus.


Dr. Michael Schmidt:  This virus has quickly spread planet-wide, within a very short period of time.  If you looked at yesterday’s map, on Monday, it had yet reached South America.  Today, it’s all down that continent.  It’s transmitted by droplet secretion.  It’s a very efficient virus.  So, if you’re in a closed space with someone, and they, indeed, have swine flu, you have, approximately, a one in five chance of acquiring it, if you’re in close proximity.  So, this virus is moving very quickly.


MUSC:  Swine flu is a particularly contagious virus that spreads quickly.  However, there are steps you can take to minimize your chances of getting flu.


Dr. Michael Schmidt:  Those things are:  washing your hands, making certain that when you have to sneeze or cough, you cover your cough and control your sneeze.  The best way to do that is by placing your nose in the inner side of your elbow.  Fresh air and sunshine are not friends of flu.  The virus is quickly inactivated in sunlight.  And, social distancing is one of our best defenses.


MUSC:  Once you contract the virus, the development of symptoms occurs rapidly.


Dr. Michael Schmidt:  From exposure to symptoms, typically, is two days.  This virus appears to be a little bit more aggressive, and you can actually begin to display symptoms as earlier as one day; and as late as four days.  So, if you think you’ve had flu, you can probably trace your contact back to the time that you got it.  It’s not like one of these long-acting viruses, like hepatitis, where it’s six months before you display symptoms.  This virus, you know when you’ve got it because of the muscle aches, the fever, and the upper respiratory involvement.  So, you know when you have the symptoms.


The downside of influenza is that you can be infectious 24 hours before you display symptoms.  So, again, that is why it’s important to monitor hand hygiene, as well as the hygiene of your environment.  You want to make certain that your environment is appropriately disinfected, should you have numerous people in your home or workplace.  You want to make sure that your countertops are wiped down, and that anywhere that a foreign body can live is clean.


MUSC:  It’s important to take this virus seriously because influenza can be fatal, especially for the very young and very old.


Dr. Michael Schmidt:  Influenza kills 36,000 each year.  And that’s just garden variety flu, for which we have a vaccine.  This flu appears to be going after the young and the immune-compromised.  And, the argument that the experts are making is that it’s because it’s a new variety, a new variant, of influenza which we’ve never been exposed to. 

This swine flu has been labeled H1N1, and historians in the listening audience may appreciate that the 1918 variant was named H1N1.  This one is the same name, but it’s just a little bit different, which is confusing our immune system.  So, the question is whether older folks that have had the vaccine for H1N1; H1N1 was in this year’s vaccine strain that many of us got last October, will be protected.  The question that many folks are asking in the immunological world is, will that provide a level of protection?  The level of protection, typically, of vaccines is that you don’t get sick. 

But this virus has changed its spots just a little bit, such that the vaccine that we’ve had may not confer protective immunity, but rather just limit the severity of disease.


Dr. Linda Austin:  Although swine flu has been around for a long time, this particular strain has changed, or mutated, so that it has become a threat to people.


Dr. Michael Schmidt:  This particular strain of influenza; swine influenza, is gaining prominence because the swine flu virus typically doesn’t infect humans.  The interesting thing about influenza is that it’s Mother Nature’s random number generator.  This virus is not very large, and it has a very bad RNA polymerase that replicates itself.  The best metaphor for that is that it types badly.  And, on average, it makes a mistake each time it makes a new copy of itself.  So, as you can imagine, it changes things.  And that’s called the process of mutation.


The other aspect of influenza is that it has eight chromosomal segments.  And the only thing this virus requires in order to infect our cells is the right receptor that interacts with our cells.  And these cells, typically, are in our lungs.  So, this swine flu variant got the right receptor mix in this shuffling process.  It’s anticipated that this occurred with an antigenic drift, and an antigenic recombination event, where it came from a human and pig virus getting together in the same cell.  And what happened is that it was the random process of pulling one other chromosomal segment from a human virus, and the others from the pig virus.  And then that consequence is that you’ve got a new chimeric virus that can easily infect people.


MUSC:  We’ll keep you posted on the development of the swine flu epidemic.  Thanks for listening.  

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