Emergence of Novel H1N1 Raises Pandemic Concerns

indigo girl · Jul 22, 2010

Not an easy commentary to understand, but the information may be important some time in the future. What is being described here are different strains of influenza that are cirulating in addition to the pandemic strain (pH1N1). There were some disturbing similiarities found in recent strains that were similiar to those found in attendees at a fair where animals were shown (swine). The concern is that these two strains are co-circulating and exchanging genetic information. They won't be targeted by our current vaccines either, and that could be bad news for future if they become more virulent. The author is saying that this is probably what happened in 1918. The influenza going around initially was not very virulent then but, later became very dangerous possibly due to continuous recombination of strains occurring in swine. At least that is my take on what is being said here.

The two most recent H1N1 isolates in swine that were not pandemic H1N1 had the duplication. Both isolates were collected in June, 2010 (in Iowa and Illinois) and suggest that this strain is rapidly spreading.
This duplication is on a genetic background most closely related to swine and human isolates from a Hudson County fair in Ohio in August, 2007. In addition to the isolates from a presenter (10F) and her father (36M), 24 attendees had flu-like symptoms, indicating the strain was readily transmitted from swine to humans, but the transmission was not sustained and did not lead to a pandemic.
However, the duplication at positions 157 and 158, combined with recent genetic acquisitions from pH1N1 raises concerns that efficient transmission in humans may develop in the near term. pH1N1 is also widespread in Midwestern swine, as is H1N2, which has a human seasonal H1.
The co-circulation of two distinct triple reassortants with a North American swine H1 allow for rapid evolution via recombination. Most of the newly acquired polymorphisms in pandemic H1N1 trace back to North American swine, and many of the new polymorphisms in the H1N1 with the duplication trace back to pH1N1. This two way exchange of genetic information via recombination leads to rapid evolution , which may include efficient transmission in humans. Both H1N1 strains readily transmit in swine, while pH1N1 readily transmits in humans. Moreover, the frequency of low reactors in pH1N1 was on the rise in the spring of 2010.
The co-circulation of a human adapted H1N1 with a swine H1N1 raises concerns sequences with extensive recombination will emerge in 2010, as happened in 1918.