1. PHYSICO-CHEMICAL AND BIOLOGICAL PROPERTIES OF TYPE O FOOT AND MOUTH DISEASE STRAINS ISOLATED FROM SOUTH AMERICAN OUTBREAKS (2006 TO 2011)
Galdo Novo S1, Espinoza AM2, Cardillo S2, Maradei E1, Guinzburg M2, Lago Aladro E1, Perez Beascoechea C1.
1 Servicio Nacional de Sanidad y Calidad Agroalimentaria – Dirección General de Laboratorio y Control Técnico – DLA / 2 Biogénesis Bagó- Buenos Aires- Argentina C

2. FOOT AND MOUTH DISEASE VIRUS
Family; Picornaviridae
Genus; Aphtovirus
+ Single Stranded RNA
Susceptible Species; cloven-hoofed animals
Clinical symptoms; FEVER, VESICLES IN MOUTH AND HOOVES, EXCESIVE
SECRETION OF SALIVA, WEIGHT AND MILK PRODUCTION LOSS

3. FOOT AND MOUTH DISEASE VIRUS
No reported outbreaks since 2011

4. FOOT AND MOUTH DISEASE VIRUS
Threat of introduction
expansion of FMD free areas
increasing movement
of animals and products.

5. FOOT AND MOUTH DISEASE VIRUS
FMD reference laboratory and antigen bank
continuously monitoring
if FMD viruses from new outbreaks
are matched by vaccine strains available.
New vaccine strain candidates of
vaccine and
antigen banks.

6. Purpose of this study Evaluation as candidate strain for antigen bank
FMDV Strains isolated from outbreaks occurred from 2006 to 2011 in South America
Isolation
Sequencing
Vaccine matching by VNT
Poor Match
BHK-21 cells cultivated in rollers of 24hs were used for rating the hours at which CPE was registered at different MOIs
For evaluating lethality in suckling mice, 6 suckling mice between 2-4 days year old were inoculated per dilution of virus and SMLD (suckling mice lethal dose) 50%/ml was registered up to 7 days after inoculation.
For susceptibility to 37°C, aliquots of the different strain suspension were prepared and incubated at 37°C. One aliquot of each strain was titrated at 0,2,4,6,8,10,24,48 and 96 hours after the incubation at 37°C had started. An inactivation curve was constructed.
Finally for antigenic payload yield determination, viral suspensions at the best / optimal / synonyms-?? MOI were first inactivated, as in vaccine production procedure, then concentrated and purified in sucrose 20-45% solution and ultra centrifuged overnight. The sucrose fraction with 140s particles was determined with a spectrophotometer and Antigen Mass was then quantified.
Evaluation as candidate strain for antigen bank
Maradei et al., 2012 – Maradei et al., 2013

7. Evaluated Strains compared with currently used vaccine strain O1 campos/Bra/58
O Corrientes/Arg/06 (O-Corr)
O/Napo/Ecu/46-10 (O-Ecu)
O/SanPedro/Par/11

8. Desirable properties for a candidate strain
Infectivity in BHK 21 cells at different multiplicities of infection (MOI),
Cytopathic effect (CPE),
Antigen production yield.
Susceptibility to temperature (37ºC)
Capable of propagate in BHK 21 suspension cultures with adeccuate yield
Virus stability before and after inactivation
Inmunogenicity / Protection induced by the antigen after formulation in a vaccine

9. RESULTS

10. 13 hours
MOI Yield 1:10000

11. Figure 1 IDCT50%/ml vs. incubation time of strain suspension at 37°C

12. CONCLUSIONS
Importance of evaluation of new isolated Foot and Mouth Disease for maintenance and improvement of antigen banks for providing help in case of new outbreaks.
O/Napo/Ecu/ good candidate
O/Corrientes/Arg/06 possible candidate
O/San Pedro/Par/11 bad candidate
Further antigenic studies will be necessary to consider these viruses in strain collections as potential vaccine strains.

13. Claudia Perez Beascoechea
Enrique Lago Aladro
Andrea Pedemonte
Ricardo D´Aloia
Eduardo Maradei
Eliana Smitsaart
Sabrina Cardillo
Ana María Espinoza
Mariela Guinzburg

14. Thank you! www.senasa.gob.ar
DVM Sabrina Galdo Novo, Esp.