The Role of Vaccine for PRRS Control in Growing Pigs

Iowa Pork Congress

Educational Seminar

January 23rd, 2008

PRRSV in Growing Pigs: Economics

• Most current measures of PRRS control are targeted at breeding herds

• However; recent reports from NPB and ISU indicate that 88% of the costs associated with PRRS are incurred in growing pigs– PRRS adds $6.01 cost/pig in nursery phase– PRRS adds $ 7.67 cost/pig in finish phase

• Neumann E., et. al., JAVMA, 2005

PRRS in Pigs:Production Impact

The National Pork Board estimates that PRRS adds between $5.60 and $7.60 to thecost of production perhead sold.

Impact of PRRS Virus in Grow/Finish

ADG 12% Decrease

Feed Efficiency 7.5% Decrease

Percent Mortality 166% Increase

Source: Neuman, E.J.; Kliebenstein, J.B.; et.al.; Assessment of the economic impact of porcine reproductive and respiratory syndrome on swine production in the United States; JAVMA, Vol. 227, No. 3, August, 2005.

Key Questions

Heterologous Cross-Protection (Efficacy) - Do current MLV vaccines offer cross-protection to current field strains of PRRS?

What is optimal timing of vaccination for PRRS control in growing pigs?

Controlled Experimental Studies

• Halbur et. al. – Independent Research Study at ISU that evaluated

Ingelvac® PRRS ATP against challenge with 3 current and highly virulent PRRS field isolates; (JSHAP, Sept-Oct 2005 )

• Roof et. al.– Meta-analysis of 16 independent studies evaluating

Ingelvac® PRRS MLV and ATP against heterologous challenge to PRRS field isolates; (5th Int. Symp. Emerging & Re-emerging Swine Diseases – 2007)

Meta-analysis conclusions:

• Vaccine offers consistent and repeatable protection against heterologous challenge in the respiratory model– Significant reduction of magnitude and duration of

viremia – Significant reduction of clinical disease– Significant reduction of PRRS induced lung

lesions; gross & microscopic– Significant improvement of production

performance: ADG; etc.– Vaccination needs to occur @ least 4 wks prior to

field virus exposure for optimum development of protective immunity

Controlled Experimental Studies

Halbur et. al. – Independent Research Study at Iowa State

University that evaluated Ingelvac® PRRS ATP against challenge with 3 current and highly virulent PRRS field isolates; (JSHAP, Sept-Oct 2005 )

Halbur Study Design

NA2.0 ml IMIngelvac PRRS ATP38

NANANone107

BIVI 1-8-4 / 2.0 ml INNANone106

VR2385 (1-3-4) / 2.0 ml INNANone105

BIVI 1-4-4 / 2.0ml INNANone104

BIVI 1-8-4 / 2.0 ml IN2.0ml IM

Ingelvac PRRS ATP

103

VR2385 (1-3-4) / 2.0 ml IN2.0ml IM

Ingelvac PRRS ATP

102

BIVI 1-4-4 / 2.0ml IN2.0ml IM

Ingelvac PRRS ATP

101

Challenge/RouteDose/ Route

TreatmentN Group

Halbur Study:Improvement in ADG

1.73

1.281.41

0.69

1.12

0.65

1.42

0.87

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

ATP2385ch

NONVX2385ch

ATP144ch

NONVX144ch

ATP184ch

NONVX184ch

ATPallch

NONVXallch

p<0.05

p<0.01p<0.01

p<0.01

Halbur Study: Reduction in Lung Lesions

8.4

18.4

4.2

41.6

3.6

49.2

5.4

36.4

0

10

20

30

40

50

60

ATP2385ch

NONVX2385ch

ATP144ch

NONVX144ch

ATP184ch

NONVX184ch

ATP allch NONVXallch

p<0.01 p<0.01p<0.01

p<0.05

PRRS Efficacy:Take Home Message

• Independent confirmation of vaccine efficacy at Iowa State University.– Improved ADG– Reduction of Lung Lesions– Reduction of Clinical Disease– Reduction of Post-challenge Viremia

• Trial conducted by Dr. Pat Halbur• Trial used Ingelvac ATP• Used 3 recent heterologous challenge isolates

– Heterologous Protection Exists

PRRS in Pigs:Return on Investment

Conclusions

• When used properly, vaccine provides consistent and reproducible benefits (statistically) against heterologous isolates.– Timing is Key!– Vaccine needs to be given 4 weeks prior to

field virus exposure for optimum protection!

Key Questions

Heterologous Cross-Protection (Efficacy) - Do current MLV vaccines offer cross-protection to current field strains of PRRS?

YESWhat is optimal timing of vaccination for

PRRS control in growing pigs?

4 weeks prior to PRRS exposure

Efficacy of Vaccine:

• Do experiences in the field further confirm what we see in the Lab?

Field Experiences

• System Background:• Large North American Commercial Swine System• Breeding herds have mixed PRRS Status

– PRRS negative/naïve– PRRS positive stable and unstable

• Weaned pigs sourced to nurseries based on PRRS status– 3-site production flow management– PRRS positive (stable & unstable) flow to positive nurseries– PRRS negative flow to separate PRRS negative nurseries

PRRS Profile & Vaccination Criteria

BreedingHerd

Nursery Grow-Finish

VaccinateGrowing Pigs

for PRRS?

Initiate a SowStabilization

Program?Vaccination and other measures

1 -(not infected)

_ _ NO NO

2 -(not infected)

_ + YES NO

3 +(infected & stable)

_ _ NO MaintainProgram

4 +(infected & stable)

-/+ + YES MaintainProgram

5 +(infected & unstable)

+ + NO YES

Intervention

• Vaccination w/ Ingelvac PRRS ATP implemented Feb/March 2005 to pigs at entry to PRRS positive nursery sites

• No PRRS vaccination used/needed at PRRS negative nursery sites

Results

• Compared to historical pre-vaccination performance, vaccination for PRRS @ entry to PRRS positive nurseries reduced mortality from >9% to <3%

• Vaccinated PRRS positive nursery sites performed equally to PRRS negative nursery sites

Impact of PRRS Vaccination in PRRS Positive Nurseries% Mortality

Individ.: cl: 2.53941 ucl: 6.04506 lcl: -.96624 * Rule violationRange: cl: 1.31813 ucl: 4.30669 lcl: 0 Subgrp Size 1

OO

O

O

O

O

OO

OO

O OO

O

OO O O

OO O

OO

O

OO

Individ.

cllil

uil

lwl

uwl

lcl

ucl

0

5

10

15

O

O

O

O

O

O

OO

O

O

O

O

O O OO

O O OO

O

O O O

O

O

Range

cl

lil

uil

lwl

uwl

lcl

ucl

0

2

4

6

8

DAY:MONTH:YEAR:

7105

11205

18205

3305

12305

27305

28305

1405

13505

27505

4605

22605

10705

20705

22705

10805

25805

2905

13905

28905

131005

261005

21105

21105

251105

271205

301205

Vaccination of all Positive Nurseries Started in Feb/March of 2005

Data points represent Nursery close-out data

Non-vax

Vaccinated

Total # Out

% Mortality

In Wt. Out Wt. ADG FE

PRRS PositiveVaccinated Nursery

331,462 2.65% 13.73 54.94 0.89 1.56

PRRS NegativeNon-vaccinated Nursery

337,810 3.04% 13.61 54.01 0.88 1.62

Performance of PRRS Positive Vaccinated Nurseries vs. PRRS

Negative Nurseries (2005 Annualized Data)

Take Home Message:

• Appropriate vaccination with a MLV PRRS vaccine prior to field virus exposure can dramatically reduce mortality and improve performance in nursery pigs

• Vaccinated pigs in PRRSv positive nurseries performed equally to pigs reared in PRRS negative nurseries

Implications

• Changes made in “negative” flows in 2006 to immunize for PRRS and M. hyo

• The largest finishing sites receive these pigs and PRRS exposure risks dictate need for vaccination– Allows for flexibility and functionality of nursery

flow management– YTD nursery performance shows continued

reduction in mortality & performance at target levels

Total # Out

% Mortality ADG FE

PRRS PositiveVaccinated Nursery: 2005

331,462 2.65% 0.89 1.56

PRRS NegativeNon-vaccinated Nursery: 2005

337,810 3.04% 0.88 1.62

2006 Nursery Performance: All PRRS Vaccinated

513,797 1.92% 0.86 1.67

•Performance of PRRS Positive Vaccinated Nurseries & PRRS

Negative Nurseries in 2005•Performance of All Nurseries

Vaccinated in 2006

Why Vaccine?

• The system was severely “broken”.– Some nurseries mortalities were over 15%

• The science was incontrovertible: In the growing pig model, the vaccine works!

• We knew there were other issues but believed that PRRS was the primary initiating co-factor.

• Desperate times call for desperate measures!

Lessons Learned

• First and foremost: There are no magic bullets!

• The solution to all problems is not entirely in a bottle or given via a needle!

• MLV PRRS vaccine has been a great tool but success was aided with a “systems approach”

Help Me to Help You!

• Mass Vaccination at weaning (immediately upon arrival at the nursery)

• All vaccines are given with a needle-free syringe (to reduce pig to pig transmission of field virus)

• Sow farms are monitored monthly for presence of PRRS virus circulation

• Initiate biosecurity measures with the goal of reducing transmission of PRRS virus

Biosecurity Improvements

• All pigs are moved via dedicated trucks from sow sites to transfer stations

• Needle free injectors for all piglet vaccines• Biosecurity procedures formalized• Mortality removal process• Perimeter fencing/entry gating/signage• All vehicles washed and “baked”• Biosecurity Pyramid• Attention to detail• PRRS Risk Assessments

Aggressive Preventative Approach:

• PRRS ATP (PRRS modified live)

• HP One (H. parasuis bacterin)

• M.Hyo (Mycoplasma hyopneumoniae vaccine)

• Lawsonia intracellularis (ileitis vaccine)

• Ery ALC (Erysipelas)

Barriers/Hurdles to Success

• Multi-sourced nurseries

• Unstable sow farm sources blended with pigs from naïve/stable flows

• PRRS vaccine could not be administered until pigs were weaned and delivered to the nurseries

• Multiple PRRS strains existed in the system

• Wean age

Field Experience Conclusions

• Nursery mortality was out of control• PRRS virus leaks were common and

unpredictable• PRRS ATP vaccination (among other

things) resulted in immediate reduction of mortality

• Needle-less technology allowed the use of the vaccine in multi-sourced nurseries at weaning

• Vaccination gave the confidence to combine all the flows

• Thank-you for your attention!

• Any Questions?