Vaccination of dogs using a recombinant canine adenovirus type-2 viral vector confers long-lasting immunity against rabies

Veterinary InstituteAcademy of Military Medical Science

Changchun, Jilin, China

28 May, 2007Paris

Human rabies in

China in the most recent

decade

0

500

1000

1500

2000

2500

3000

3500

96 97 98 99 00 01 02 03 04 05 06Year

CasesseHuman

rabies cases geological

distribution in China

159 222 229343

495

891

1191

2037

26512548

3215

0

500

1000

1500

2000

2500

3000

3500

1996 1997 1998 1999 2000 2002 2003 2004 2005 20062001

Year

Rabies reservoir or vectors in China

Dogs: 98%Cats: 4-5%Badger: 15 cases were reportedRats: in some areas in the south of

ChinaFoxes: Inner MongoliaWolves: XinjiangBats:?

Vaccines for dogs in China

ERA: in five combined vaccinesFlury LEP: approved for two years Inactivated (imported) : Intervet, Merial,

Fort Dodge Inactivated (home-made): 3-4 types, in clinical trial, not yet approved* Vaccination of inactivated vaccine in rural

areas needs laborious work.

Oral vaccines for dogs

▓ Attenuated or mutated live rabies virus SAD-B19 SAG1 SAG2 reverse genetically modified …… ▓ Recombinant live virus vector Poxvirus-vector based Adenovirus-vector based

Advantages of adenovirus

Safe Wide range of host Heat stable (Oral infection) Median package of a foreign gene Persistent existence ?

★ Hu RL et al. Microbes Infect, 2006, 8(4): 1090-1097

★ Liu Y, Hu R, Zhang S, et al Viral Immunology, 2006(19), 2:202-209

★ Patent1: 20041001097.8★ Patent2: 20041001200.3☆ Non-essential for replic

ation☆ Foreign gene or label ins

erts

FiberpIX

Adenovirus

Strategies for recombinant virus construction

Homologous recombination

Gene cloning

Our constructs

The recombinant CAV-2 genome containing the rabies virus glycoprotein expression cassette in plasmid form

Glycoprotein: SRV9 CVS-24 8202(street strain)Nucleoprotein: SRV9

Production of the recombinant virus

◢ Handling of canine adenovirus (safe)

◢ MDCK easy grown

◢ Obvious CPE◢ High titer:

around 10(8.5)

MDCK cells

CPE

Western blotanalysis

Bait composition

Five parts: the recombinant virus solution; pledget; tallow; metal frame; paper package

Bait uptake

Vaccination and antibody induction in dogs

Inoculation routes

Total No.

dogs

Take the baits

or vaccinated

Develop neutralizing

antibody

Antibody last for 2 years at a protective

level

Bait(oral)

96 90/96 79/90 (87.8%)

72/90(80.0%)

Solution (intranasa

l)

46 46/46 40/46 (87.0%)

36/46(78.3%)

Antibody production and persistence

Challenge results of dogs orally vaccinated and the negative

controls

Groups Number of dogs died after different time of vaccination

Dogs survived

1 week 2 weeks 3 weeks 4 weeks

5 weeks

Orally vaccinated

0 0 0 0 0 10

Negative control

0 6 3 0 0 1

Prospect

♘ In cats♘ In pigs♘ In cattle♘ and more

DogsBats

Conclusions

A new, safe and efficacious rabies vaccine

A simple and useful baitFor oral useLong lasting immunization in

dogs