PRRSV Evolution and New, Emerging Strains

Michael MurtaughXiong WangMohammad AlkhamisBob MorrisonAndres Perez

University of Minnesota

There are Two General Types of PRRSVType 1

(European)Type 2

(North American)

ORF5 Dendrogram

Lineage 1

Lineage 2Lineage 5.1Lineage 5.2

Lineage 6,7

Lineage 9

Lineage 8Type 2 PRRSV

Diversity ORF5

Lineage 1

Lineage 2Lineage 5.1Lineage 5.2

Lineage 6,7

Lineage 9

Lineage 8

1-8-4

1-7-4

2-5-2

1-4-2

1-4-2

HP PRRSType 2 PRRSV

Diversity ORF5

Type 2 PRRSV Diversity Whole Genome

HP PRRS

Ingelvac MLVReisolates Conclusions: Genbank sampling is

highly biased. No naming system.

Mlu I HincII Sac II

1 8 41 18 2

2 5 2

1 26 2

ORF50 100 200 300 400 500 600

Here are some common PRRSV RFLP types

Year 2010

1-4

1-55

1-8

March 302015 1-4 1-114 1-12

November 172015 1-5 1-125 1-13

RFLP pattern does not identify genetic relationships

1-4-4 RFLP shows up in 3 widely divergent families

Ecology of PRRSV

6774 PRRSV isolates1998-2015

Type 1N=107 (1.6%)15 years of PRRSV

Diagnostic Sequencing in USA

5 Large US SwineProducers

98.4% are Type 2

Conclusions: Large outbreaks with little

genetic change are frequent Control programs are effective Genbank does not show reality

Chinese HP-PRRSV

2006-2009 >99% identical

2006-2011 >98% identical

Type 2 PRRSV

Type 1 PRRSV One System160 ORF5 sequences

+ References

Type 2 Only

Apr 1, 2012–Jun 17, 2013

1-4-41-4-41-4-4

1-4-4

1-4-4 1-4-4

1-4-4 Outbreaks

May 21, 2014–March 31, 2015

1-7-4

1-7-4

1-7-4

1-7-4

1-7-4 Outbreaks

May 21, 2014–March 31, 2015

1-7-4

1-7-4

1-7-4

1-7-41-4-41-6-4

1-6-4

1-7-3

1-21-4

1-7-4 OutbreaksSame virus – Multiple RFLP patterns

1-7-4-PRRSV Family Story

241 1-7-4 familyJan 2014 -Mar 2015

47 n

on-1

74 fa

mily

Sept

embe

r 200

3-M

arch

2015

6774 sequences1998-2015

Anatomy of Disaster1-7-4 Outbreaks Investigation

Jun 2014Jun 2014

May 2014Apr 2014

Jun 2014Sep 2014

Dec 2014

Jan 2015

Jan 2015

The Devil’s SpawnDistant Offspring of the 1-8-4 Family

nsp2 Deletions are Unremarkable

No other distinctive features are apparent

Signal Peptide Ectodomain 1 TM Ectodomain 2

Proteins are Essentially the SameEnvelope Glycoprotein 5 (GP5)

No evidence of directed evolution or selection during outbreak

Bayesian PhylodynamicsSkyline Plot of Estimated Population Size over Time

Bayesian phylogenetic methods incorporate associated epidemiological information (e.g. geographic location, time of isolation)

History of Spread Between Systems

Outbreaks are Concentrated in Sow Farms

Dynamic representation

Shields and Mathews (2003). Interstate Livestock Movements. USDA-Economic Research Service Outlook Reportwww.ers.usda.gov/publicatons/ldp/jun03/ldpm10801/ldpm10801.pdf.

A B

Swine outflows from North Carolina Swine inflows to Minnesota

Interstate pig movements in the U.S.A. in 2001

Take Home Messages

Large-scale PRRS outbreaks in the history of type 2 PRRSV

Genetic change during outbreaks is limited

Bayesian phylodynamics helps understand disease spread

PRRSV goes where pigs go