This is especially true of viruses that contain Ribonucleic Acid (RNA), as these mutate rapidly during replication and exhibit tremendous genetic plasticity due to the built-in advantages provided by their error prone replicative enzymes and ability to genetically reassort
(when their genome is segmented) or recombine.
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Officials from the Centers for Disease Control and Prevention said in a statement that there is no evidence of human-to-human transmission of the virus but the concern is that the virus could "change and adapt to allow efficient transmission during the infection of mammals or reassort
its gene segments with human influenza viruses during the co-infection of a single host, resulting in a new virus that would be transmissible from person to person.
The inherent ability of the RNA viruses to recombine and reassort
can lead to genetic mutations and change in host range.
These risk factors include: the prevalence of the virus in livestock; its ability to bind to receptors in the human airway; its ability to grow in human cells/organs; its airborne transmissibility between ferrets (the best animal models for studying human transmission because they can transmit influenza viruses and develop clinical signs similar to those seen in humans including fever, rhinitis, and sneezing); and its ability to reassort
with human influenza viruses.
The influenza virus has shown its capacity for antigenic shift through its ability to reassort
with other flu-virus strains.
If one is unlucky enough to be simultaneously infected with an avian influenza virus and a human influenza virus, the genes in each of these two viruses can randomly reassort
, or rearrange themselves, to form a new virus.
When respiratory viruses get into these confinement facilities, they have continual opportunity to replicate, mutate, reassort
, and recombine into novel strains," Gray explains.
The concern, of course, is that the seasonal H1N1 strain of last winter will reassort
with the newly circulating novel influenza H1N1 strain to produce a new strain treatable only with Relenza.
Questions still remain about whether the disease can change or reassort
, particularly should outbreaks in countries simultaneously contending with H5N1 bird flu cases occur (such as Egypt, Vietnam, and Indonesia).
The more times this virus can get into a human, the more opportunities it will have to reassort
, mutate, or both into a form that could trigger the pandemic that many fear.
The ability of rotaviruses to reassort
during coinfections results in the exchange of genetic material between human and animal viruses and generates novel viruses.