If the H1N1 Meets the H7N9 and the H3N2v…You Have An “Armegeddon Virus”

Saturday, August 3, 2013
By Paul Martin

H1N1pdm09 PA In Ohio ex-Virginia H3N2v Case

August 1, 2013

he CDC has released a full set of sequences, A/Ohio/05/2013, from an Ohio resident who developed flu-like symptoms after attending an agricultural fair in northwestern Virginia (likely the Fauquire County Fair).

H3N2v was confirmed by the Ohio Department of Health laboratories in Reynoldsburg and the sample was forwarded to the CDC for confirmation and sequencing. The sequences from a July 22 sample included H3 N145R, which was present in the sequences from the Indiana Hancock County Fair (A/Indiana/14/2013, A/Indiana/15/2013, A/Indiana/16/2013, A/Indiana/17/2013, A/Indiana/18/2013) as well as the most recent H3N2v sequence from Indiana, A/Indiana/10/2013 (see map). N145R has not been reported in any swine sequence.

The earlier sequences in Indiana (from attendees of the Grant County Fair) had N145K, which also had not been previously reported in human cases, although this polymorphisms did appear in early 2013 swine H3N2v sequences. The presence of N145R in all of the above recent human cases (associated with agricultural fairs in Indiana and Virginia) raises concerns of human adaptation.

The latest sequence from the Ohio DoH sample also has a novel constellation of genes, which includes H1N1pdm09 PA, which also has never been reported in humans (or swine). Five of the gene segments (PB2, H3, NP, N2, MP) are closely related to the 2013 Indiana H3N2v cases. However, the other three gene segments (PB1, PA, NS) have been circulating in recent H3N2v swine (which have internal genes closely related to human sequences from 2011) and two of the genes (PB1 and NS), are closely related to the sequences from 2012 Minnesota H1N2 cases.

The acquisition of three gene segments in 2013 is similar the genetic changes which produced the constellation of genes seen in the human cases in 2011. That constellation had 5 gene segments matching 2010 human cases (PB2, PA, H3, NP, NS), but acquired the other three gene segments (PB1, N2, MP) from H1N2 swine, which included am H1N1pdm09 MP gene segment.

The time frame for the appearance of the novel constellation in 2013 is similar to the appearance of the novel constellation which included H1N1pdm09 MP in 2011.

The new constellation in 2013, coupled with the acquisition of N145R, raises concerns for a larger number of H3N2v human cases in 2013.

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