38.5

39.0

39.5

40.0

-1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Mean

recta

l te

mp

era

ture

(°C

)

Vaccinates

Controls

D-1 D0 D1 D2 D3 D4 D13 D14 D15 D16 D17 D18 D27 D28 D29 D30 D31 D32

Figure 1: Evolution of mean rectal temperature following each injection

p=0.487, Student t test

*p=0.006, Student t test

p=0.744, Mann Whitney W test

SAFETY OF A BIVALENT BTV-4/BTV-8 INACTIVATED VACCINE IN YOUNG CALVES

Galleau S.1 - Hamers C.1 – Hudelet P. 1 – Blanchet M.1 – Maurin-Bernaud L. 1 –Duboeuf M.1 – Goutebroze S.1

1 Merial S.A.S. – 69007 Lyon, France

®BTVPUR ALSAP is a registered trademark of Merial.

Bluetongue (BT) outbreaks have seriously affected the cattle and sheep industries in Europe. Since 2008, large-scale vaccination programmes using inactivated vaccines have been conducted in Europe to control BTV infections, notably against BTV-8. Inclusion of young animals in the vaccination programme is not only essential for the success of a BTV control strategy but also to ensure safe animal movements. Consequently, safety of a vaccine to be used in young animals is of great importance for farmer’s acceptance of the vaccination strategy.

Introduction

Material & method

Study design

Twenty BTV sero-negative calves, aged between 23 and 30 days, were randomly allocated to 2 groups of 10 animals each, on the basis of their body weight:

Vaccinates: injected with the vaccine by SC route on D0 (double dose of 2 mL), D14 and D28 (repeated single dose of 1 mL). Each vaccination was performed at separate injection sites.

Controls: injected with placebo (physiological saline) in the same conditions as for vaccinates

Monitoring

- Individual clinical examination and recording of rectal temperature for 4 days following each injection.

- Monitoring of local reactions until D49 with subsequent necropsy and histological analysis of the injection sites.

- Recording of body weight gain.

ResultsClinical monitoring

Except very transient apathy and decrease of appetite in one calf following the second injection, no treatment-related general reactions were recorded.

ConclusionThe administration of an overdose and repeated administration of one dose of the overformulated bivalent BTV-4/BTV-8 inactivated vaccine was demonstrated to be safe in one-month-old calves and does not impact the daily weight gain. The use ofcommercial BTVPUR ALSAP can thus be considered safe in young cattle.

The mean maximal temperature increase was +0.5°C, following the second injection. Globally, the temperature increase remained very moderate and transient.

The present study assessed the safety of an overdosed BTV-4/8 bivalent vaccine of the BTVPUR ALSAP® range administered to young calves.

Local reactions

Only limited swelling reactions were observed at the injection sites, particularly after the 2nd and 3rd injections likely due to increased inflammation in already primed animals. They had disappeared on D49 in all the calves except one (D28 injection site).

At histology, modification of very limited size, corresponding to a classical local subcutaneous foreign-body-like lesion (granulomatous inflammatory reaction), was recorded in only one third of the injection sites.

Body weights

There was no impact of the vaccinations on the body weight gain.

Table I. Relative Average Daily Weight Gain (% / day) per group

Group Mean ± Sd Statistical comparison

Vaccinates 1.3 ± 0.3p=0.993

(Sudent t test)Controls 1.3 ± 0.3

Figure 2: Evolution of average local reactions size in vaccinates after each injection

0

2

4

6

8

10

12

14

16

18

0 10 20 30 40 50

Day of observation

Mean

su

rface

of

loca

l re

act

ion

(cm

2)

1st injection site (2 mL on D0)

2nd injection site (1 mL on D14)

3rd injection site (1 mL on D28)

Figure 3: Distribution of individual body weights measured in vaccinates

and controls on D-1 and D49

D-1 D49

Box-and-Whisker Plot

Body

wei

ght

(kg)

Vaccinates Controls Vaccinates Controls43

53

63

73

83

93

103

Vaccine

To mimic any of the mono or bivalent combination of the BTVPUR ALSAP range, an overformulated bivalent BTV-4/BTV-8 inactivated vaccine was produced.