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

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

FOOT AND MOUTH DISEASE VIRUS No reported outbreaks since 2011

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

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.

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

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

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

RESULTS

13 hours MOI Yield 1:10000

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

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/46-10 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.

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

Thank you! www.senasa.gob.ar DVM Sabrina Galdo Novo, Esp. sgaldo@senasa.gov.ar