Characterize to control: analyzing the spread of pig disease to prevent epidemics

The spread of Type 2 Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) in North America: A phylogeographic approach

Read the full article on ScienceDirect.

We have witnessed in recent years a proliferation of phylogeny-based tools tailor-made for the study of viruses, which incorporate temporal, geographic, and genetic information to reveal their epidemiological history and dynamics. These tools are especially useful in cases when surveillance and field epidemiology efforts fail to provide any insightful information into the dynamics of a virus.

In this study, we focused on an economically important Type 2 Porcine Reproductive and Respiratory Syndrome Virus (Type 2 PRRSV). In North America, Type 2 PRRSV poses constant threat to domestic swine populations but its emergence and spread are largely uncharacterized.

Our study employed state-of-the-art phylogeographic analyses on 7040 ORF5 gene sequences to reveal the recent geographical expansion history of Type 2 PRRSV in North America. Particularly, our results demonstrated multiple viral introductions from Canada to the United States driven by the unidirectional transportation of feeder pigs across the border. As a result, Canadian-like PRRSVs have been gradually replacing endemic viral populations as the dominant variants in the Midwest regions of the United States. Furthermore, our study underscores hog transportation as the key factor contributing to large-scale virus movement. Indeed, the directions and intensities in our reconstruction of virus traffic network was almost a mirror image of hog transportation in North America.

In summary, our findings provide important insights into the dynamics of Type 2 PRRSV population structures that will facilitate control and prevention programs.

Schematic showing North American PRRSV circulation among swine production regions, including CAN (Canada), Manitoba (MB), Ontario (ON), Quebec (QC), AP (Appalachia), CB (Corn Belt), LS (Lake States ), MU (Mountain), NP (Northern Plain), NT (Northeast), and SP (Southern Plain). The size of the circle reflects the PRRSV sample size in each region, while the thickness of lines with arrows indicates the frequency of inter-regional virus flows. The picture of inter-regional PRRSV circulation was separated into two parts: (A) Lineages 1–2 PRRSV flows, where both Canada and United States were involved; and (B) Lineages 5–9 PRRSV flows, almost exclusively within the United States.

Schematic showing North American PRRSV circulation among swine production regions, including CAN (Canada), Manitoba (MB), Ontario (ON), Quebec (QC), AP (Appalachia), CB (Corn Belt), LS (Lake States ), MU (Mountain), NP (Northern Plain), NT (Northeast), and SP (Southern Plain). The size of the circle reflects the PRRSV sample size in each region, while the thickness of lines with arrows indicates the frequency of inter-regional virus flows. The picture of inter-regional PRRSV circulation was separated into two parts: (A) Lineages 1–2 PRRSV flows, where both Canada and United States were involved; and (B) Lineages 5–9 PRRSV flows, almost exclusively within the United States.

Introducing the authors
MangShi_Pic Leung_Pic
(L) Mang Shi, Sydney Emerging Infections & Biosecurity Institute, The University of Sydney, Australia
(R) Fred Leung, The University of Hong Kong, and Nanjing Agricultural University, China

About the research

The spread of Type 2 Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) in North America: A phylogeographic approach

Virology, Volume 447, Issues 1–2, December 2013, Pages 146–154
Mang Shi, Philippe Lemey, Manreetpal Singh Brar, Marc A. Suchard, Michael P. Murtaugh, Susy Carman, Sylvie D’Allaire, Benjamin Delisle, Marie-Ève Lambert, Carl A. Gagnon, Li Ge, Yihan Qu, Dongwan Yoo, Edward C. Holmes, Frederick Chi-Ching Leung

Read the full article on ScienceDirect.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>