THE MOLECULAR BASIS OF INHERITANCE
THE GENETICS OF VIRUSES AND BACTERIA
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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An avian flu virus undergoes several mutations and rearrangements such that it is able to be transmitted to other birds and then to humans.
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A flu virus from a human epidemic or pandemic infects birds; the birds replicate the virus differently and then pass it back to humans.
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An influenza virus gains new sequences of DNA from another virus, such as a herpesvirus; this enables it to be transmitted to a human host.
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An animal such as a pig is infected with more than one virus, genetic recombination occurs, the new virus mutates and is passed to a new species such as a bird, and the virus mutates and can be transmitted to humans.
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Detailed explanation-1: -Antigenic Shift Shift can happen if a flu virus from an animal population gains the ability to infect humans. Such animal-origin viruses can contain HA or HA/NA combinations that are different enough from human viruses that most people do not have immunity to the new (or “novel”) virus.
Detailed explanation-2: -Antigenic shift occurs because influenza A viruses have a large animal reservoir, consisting primarily of wild aquatic birds (e.g., ducks).
Detailed explanation-3: -Fortunately, these shifts occur only occasionally, having caused only a handful of true flu pandemics in the past century. Major antigenic shift only happens to influenza A viruses. Influenza B viruses only undergo antigenic drift. 1 H1N1: From Pandemic to Seasonal Flu Type.
Detailed explanation-4: -This phenomenon is referred to as antigenic drift.