Efficacy of a square presentation of

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Efficacy of a square presentation of V-RG
vaccine baits in red fox, domestic dog and
raccoon dogs
F. Cliquet1, A.L. Guiot2, C. Schumacher3, J.
Maki3 and J. Barrat1
1 WHO Collaborating Centre for Research and
Management in Zoonoses Control, OIE Reference
Laboratory for Rabies, Community Reference
Laboratory for Rabies Serology, AFSSA Malzéville,
France 2 Conseils en Pharmacie et Biologie Santé,
Lyon, France 3 Merial, Lyon (France) and Athens
(USA)
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V-RG rabies vaccine
V-RG vaccine (Raboral V-RG) is a vaccinia
virus recombinant coding for the rabies
glycoprotein gene.
V-RG vaccine baits have been extensively used
in France and in other European countries which
are all rabies free (France, 2000 Belgium and
Luxembourg, 2001) and is currently used in US and
also in Ukraine.
This vaccine is one of the two vaccines
recognised and recommended by the European
Commission (2002) and WHO (2005) for oral
vaccination of foxes against rabies.
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Objective
To evaluate in captive animals (domestic dog, red
fox and raccoon dog) the efficacy of a square
V-RG bait produced in USA in captive animals
Evaluation of ? Attractiveness of the
baits ? Induction of neutralising antibodies ?
Protection after rabies challenge
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Experimental design
Number of animals
DO Vaccination
Vaccine titre
Challenge
vaccinated controls
9 3
square VRG placebo bait
108.4 TCID50/dose -
D30 New York rabies strain
Dogs
D91 Salivary gland homogenate from rabid foxes,
400 MIC LD50
vaccinated controls
10 10
square VRG placebo bait
108.4 TCID50/dose -
Foxes
D214 Salivary gland homogenate from a naturally
infected coyote (CDC), 1600 MIC LD50
vaccinated controls
10 9
square VRG NA
108.8 TCID50/dose -
Raccoon dogs
NA not administered All animals daily observed
and kept at least for 90 days after challenge
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Results - Bait acceptability
Bait uptake time
Bait consumption in
Species
vaccinates
placebo
8/9 1/9
1/3 2/3
less than 1 hour less than 24 hours
Dogs
Foxes
10/10
10/10
less than 24 hours
mean time of disappearance 4.2 hours (SD 7
hours)
Raccoon dogs
10/10
-
Doubtful for two foxes
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Results Dogs rabies virus neutralising
antibodies and resistance to challenge

• S survive
• D die
• Only one dog out of 9 vaccinates seroconverted
• All three controls died between D14 and D17
• One vaccinate died at D15

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Results Foxes rabies virus neutralising
antibodies
2 vaccinated foxes did not seroconvert
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Results Foxes resistance to challenge
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Results Raccoon dogs rabies virus neutralising
antibodies
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Results Raccoon dogs resistance to challenge
Group
Vaccinated
Controls
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Discussion

• The square fishmeal polymer bait V-RG is well
  accepted by dogs, foxes and raccoon dogs.
• The rate of seroconversion following bait uptake
  as well as the magnitude of antibody titres are
  different in the 3 species

The high levels of rabies antibodies observed in
raccoon dogs have been also observed when
vaccinated with an attenuated oral vaccine
(Cliquet and al, 2006)
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Discussion

• The challenge was validated since all controls
  died from rabies (typical rabies signs were
  observed and diagnostic tests positive).
• Protection after challenge was satisfactory in
  the three species tested.
• Dogs protection (8/9 dog) despite absence of
  seroconversion already largely documented.
• Foxes protection in 8/10 foxes two
  vaccinated foxes did not seroconvert and
  succumbed to rabies challenge.
• Raccoon dogs protection in all vaccinated
  raccoon dogs.

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Conclusion

• The square fishmeal polymer bait V-RG tested in
  domestic dogs, foxes and raccoon dogs was
  attractive, immunogenic and efficient.
• The efficacy data support the idea of a
  potential sourcing of this oral rabies vaccine

• for oral vaccination campaigns in those European
  countries where both foxes and raccoon dogs
  represent major wildlife species affected by
  rabies,
• for oral vaccination of dogs as a complement to
  other means (parenteral vaccination and ABC
  programs) in countries where canine rabies is
  endemic.

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ACKNOWLEDGMENTS

• Chuck Rupprecht (CDC)
• Jacqueline Bailly, Michel Munier, Nicolas Penel,
  Josiane Ambert, Jean-Michel Bousset, Audrey
  Hamen, Michel Ritleng, Chantal Patron, Patricia
  Grosgeorge, Anouck Labadie, Estelle Litaize and
  Sébastien Kempff and Jean Luc Schereffer (AFSSA
  Nancy)