Swine Flu Natural?
The Swine Flu has been covered ad nauseam in the media, with many aspects addressed, however little has been elucidated on the first (and most important) question I had when this strain broke loose:
How can three virus strains combine, in nature, to form a single, viable virus?
To answer this question we need to look at a little bit of background information on the Influenza A virus (in brief). It is an RNA virus, a genus of the Orthomyxoviridae family. The virus itself lacks most of the needed equipment (enzymes and so forth) for replication and depends on the body’s own cells, which it enters on contact with outer membranes. The protective viral coat breaks open inside the cell, with the RNA being fed to the cell’s protein making “factories” to reproduce the viral coat which protects the virus and enables its further spread, and also the enzymes necessary to replicate the virus’ RNA (RNA Polymerase). The completed virus particle either continues to reproduce inside the cell, or is expelled by the cell itself, where, if successful, it survives long enough to infect another cell.
The replication process itself is very error prone (much more so than that for human DNA), such that many of the viral copies fail. Some errors work, however. This may result in a more “successful” viral particle. This system of natural selection means that, over time (sometimes a very short time), a virus adapts to its host, which can be a good or bad thing:
- The virus might develop a slower replication rate, so that the symptom free phase is longer, allowing it to spread to more hosts. This would make it a better virus than one which kills its host so quickly that it has never had a chance to spread to a new host.
- The virus might develop into a more benign form, so that it can spread happily without the host minding too much. This could be an advantage for the virus, for example, if the sickest individuals were quarantined (or dead), rendering that viral trait undesirable and selecting for less severe traits.
- The virus might develop into one which can survive a longer time in the atmosphere, increasing its infectiousness. It could be said that the universal wearing of surgical masks, for example, might mean that the virus will be pressured into learning how to spread in more extreme conditions (past the mask), making it more virulent.
Many of the symptoms of flu virus are deliberate, such as mucous membrane irritation which causes people to sneeze and cough, or develop diarrhoea. These aide the spread of the virus, which is why hand washing and the wearing of masks is advocated by authorities. On the other hand, measures to stop the virus can promote a super-strain which can make matters worse.
The important point, to answer the question, is that the Viral RNA is not presented as a single strand but, in the case of Influenza, eight separate segments. These float around near the nucleus of the cell relatively freely until they are repackaged. Thus, it is possible (either in a laboratory or in nature) for a cell to be infected by two different virus strains simultaneously, resulting in any number of random combinations of the Viral RNA segments, any of which may potentially result in a successful virus particle. Most of the time, however, it can be expected that recombinations would fail.
The combination of two virus strains can easily occur in nature. Three is less likely.
However, it should take a long time for three viruses to combine into one coat. Long enough for a precursor to have spread widely, causing animals to get sick so that they get tested, perhaps to the point that the new genome is detected in a laboratory, before a third virus is incorporated into the new strain. It should also be possible to find a virus having a combination of two of the three RNA strains somewhere else in the wild. This may have occurred already in pigs in Ohio (2007). There are doubts, however, that the Ohio outbreak is not a red herring, as is covered well here.
Yet it is now reported by wired magazine that the viral genome is entirely made up of elements from pigs only and only from two, pre-existent strains, a claim that needs further corroboration. But if this is true, then the almost-pandemic A/H1N1 virus can safely be viewed as one having developed entirely naturally, but precursors still need to be found.
Swine Flu A Natural Occurrence?
The current outbreak of Swine Flu is probably a natural occurrence, but the work necessary to show this is incomplete. The question, as at 1/5/2009, remains unanswered, and thus, the theory that the outbreak was no accident, cannot yet be discounted as just another of the flighty ideas of a paranoid lunatic.
(As this stage, we won’t be covering any more of this epidemic, unless something new and meaningful is learned of the virus itself. Instead, we intend on concentrating on other, more pressing matters.)