Comparative Efficacy Evaluation of Two Modified-Live PRRS Vaccines

AASV Annual MeetingIndustrial Partners February 28th, 2016

Study Objective

• Directly compare the efficacy of Ingelvac PRRS® MLV and Prime Pac™ PRRS+ against a heterologous PRRSV challenge in a standard respiratory challenge in growing pigs

Primary Objective: Question?

• Are there detectable – measurable efficacy differences between Ingelvac PRRS® MLV and Prime Pac™ PRRS+ following a relevant heterologous PRRSV challenge?

Study Design• Randomized and blinded vaccination-challenge study

• Pigs used for the study were 3 wks of age and PRRSV naïve – confirmed PCR negative

• Day 28 Challenge (4 wks post-vaccination) w/ PRRSV SDSU-73• 89.7% homologous to Ingelvac PRRS® MLV• 91.3% homologous to Prime Pac™ PRRS

• Day 42 Post-challenge necropsy (2 wks post-challenge)• Lung lesion evaluation for percent pneumonia associated

w/ PRRS exposure

Study Design

Group

No. of Ingelvac PRRS® MLV

Vaccinated Pigs (2ml IM)

No. of Prime

PacTM PRRS Vaccinate

d Pigs(1ml IM)

No. of Challenge

Control Pigs

PRRSV SDSU-73

Challenge Dosage(Log10

TCID50/ml)

Necropsy Subset of Groups 1,2 & 3

(lung lesion)

Necropsy Remaining

Pigs

Day 0 Day 0 Day 0 Day 28 Day 42 Day 70

1 20 - - 4.1 10 10

2 - 20 - 4.1 10 10

3 - - 20 4.1 10 10

4 10 - - None 10

Study Design

· Parameters measured – Comparative Efficacy Objective

Parameter Day

% Lung Lesions 42

ADWG 28-70 (post-challenge period)

Viremia 28-70 (post-challenge period)

Pyrexia/Temperature 28-42 (post-challenge period)

Results – Lung Lesions

• Both vaccinated treatment groups demonstrated a large and similar reduction in lung lesion scores compared to the non-vaccinated challenged treatment group.• Greater than 85% reduction

• The Ingelvac PRRS® MLV vaccinated pigs median lung score was 0.5% vs. 1.3% for Prime Pac™ PRRS+ group.

Group TreatmentMedian Percent

Lung Score

1 Ingelvac PRRS® MLV 0.5

2 Prime Pac™ PRRS+ 1.3

3 Challenge Control (non-vaccinated) 28.6

Results – Viremia· Decline in post-challenge viremia begins earlier in Ingelvac PRRS® MLV

vaccinates. From day 42-63 of the study, Ingelvac PRRS ® MLV vaccinates demonstrate less percent PCR positive pigs than Prime PacTM PRRS and challenge control pigs.

· Prime PacTM PRRS vaccinated pigs viremia pattern following challenge is similar to challenge control pigs.

Figure 1. Percentage of viremic pigs per treatment group following PRRSV SDSU-73 challenge

28 31 33 35 38 42 49 56 63 700%

20%

40%

60%

80%

100%

120%Ingelvac PRRS® MLV

Prime Pac PRRS

Challenge Con-trol (non-vac-cinated)

Ingelvac PRRS® MLV (no Challenge)

Days

% P

CR P

osit

ive TM

Results – Pyrexia/Fever· Ingelvac PRRS® MLV vaccinated pigs maintained lower average

temperatures throughout the challenge phase of the study when compared to challenge controls

Figure 2. Average daily temperature by treatment group

27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 4239.239.439.639.840.040.240.440.640.8

Ingelvac PRRS® MLV

Prime Pac PRRS

Challenge Con-trol (non-vac-cinated)

Ingelvac PRRS® MLV (no challenge)

Days

Deg

rees

(C°)

TM

Results – Pyrexia/Fever· Ingelvac PRRS® MLV vaccinated pigs also demonstrated lower average

temperatures compared to Prime Pac™ PRRS+ vaccinated pigs during the first week post-challenge

· During the first week post-challenge, average temperatures in the Prime Pac™ PRRS+ vaccinated pigs were similar to the challenge controls

Figure 2. Average daily temperature by treatment group

272829303132333435 36373839 40414239.239.439.639.840.040.240.440.640.8

Ingelvac PRRS® MLV

Prime Pac PRRS

Challenge Con-trol (non-vac-cinated)

Ingelvac PRRS® MLV (no challenge)

Days

Deg

rees

(C°)

TM

Results – Average Daily Weight Gain (ADWG) • Ingelvac PRRS® MLV vaccinated group demonstrated a 17%

higher ADWG compared to both Prime Pac™ PRRS+ & non-vaccinated challenge control groups• ADWG for Prime Pac™ PRRS+ & challenge control groups were similar

• Vaccinated non-challenged group demonstrated best ADWG, indicating the virulent PRRSV challenge has biologic impact as measured by ADWG

Group Treatment Group ADWG (lbs)

1 Ingelvac PRRS® MLV 1.41

2 Prime Pac™ PRRS 1.17

3 Challenge Control(non-vaccinated) 1.18

4 Vaccinated Control(non-challenged) 1.67

Conclusions

• Both Ingelvac PRRS® MLV and Prime Pac™ PRRS+ vaccines demonstrated a large and similar reduction in PRRSV associated lung lesions compared to non-vaccinated controls

• Reduction in post-challenge viremia occurred earlier in Ingelvac PRRS® MLV vaccinated group compared to Prime Pac™ PRRS+ vaccinated group- Pattern of viremia reduction in the Prime Pac™ PRRS+

vaccinated group was similar to non-vaccinated controls

Conclusions• Ingelvac PRRS® MLV vaccinated group maintained lower average

temperatures throughout the challenge phase of the study compared to Prime Pac™ PRRS+ and challenge control groups• Reducing fever following challenge/infection is important to mitigate

consequences of infection – helping pigs return to normal feed & water intake

• Ingelvac PRRS® vaccinated group had 17% higher ADWG compared to both Prime Pac™ PRRS+ and challenge control groups

- Mitigating the negative biologic impact PRRSV infection has on ADWG can have significant economic benefit

• In this study, the slower mitigation of viremia & temperature following challenge in the Prime Pac™ PRRS+ group may have had a negative impact on overall ADWG

• This study is another example demonstrating the ability of modified-live PRRS vaccines to protect against a relevant PRRSV challenge