Viral determinants of FMDV A/Arg/01 virulence in adult mice

CACCIABUE, MARCO; CURRÁ, ANABELLA; KÖNIG, GUIDO; RIEDER, ELIZABETH; OSCAR, TABOGA; CARRILLO, ELISA; GISMONDI, MARÍA INÉS

Congreso; GFRA 2019; 2019

Viral determinants of FMDV A/Arg/01virulence in adult miceCacciabue, Marco1,2; Currá, Anabella1,2;König, Guido1; Rieder, Elizabeth3; Carrillo, Elisa1;Gismondi, María Inés1,21Institutode Agrobiotecnología y Biología Molecular (IABiMo, INTA-CONICET), Hurlingham,Argentina2Universidad Nacional de Luján, Luján, Argentina3PlumIsland Animal Disease Center, ARS, USDA, Greenport, NY, USA. Different animal models including adult C57 Bl/6J micehave been used to study FMDV biology and host susceptibility to viralinfection. We previously characterized two FMDV A/Arg/01 variants derived fromfield isolates that circulated in Argentina during the 2000-2001 epizootia.These viruses exhibit differential virulence in adult C57 Bl/6J mice: FMDVA01NL is a non-lethal variant that causes mild signs of disease, whereas FMDVA01L is a lethal virus that causes death of all mice within 24-48 h,independently of the dose used (102-106 pfu/mice,intraperitoneal injection). Histological analysis showed that both viruses producea systemic infection with pathological changes in the exocrine pancreas.Complete consensus sequences revealed 31 nucleotide changes between FMDV A01NLand FMDV A01L (6 non-synonymous, 23 synonymous and 2 changes in the 5?non-coding region). To evaluate the role of non-synonymous mutations (C2211Tand T2515C in VP2, C3688T and A3775T in VP1, A4579G and A5086G in 2C) in thedifferential pathogenicity of both FMDV variants, a set of seven chimericalviruses with the mutations of FMDV A01L in the genetic backbone of an FMDV A01NLcDNA clone (A01NLc) were obtained and characterized. The engineered virusesinclude single substitutions (viruses 2211Lc, 2515Lc, 3688Lc, 3775Lc) ormultiple mutations (viruses CapL, containing the VP2 and VP1 mutations; 2CL,containing the mutations present in 2C; and A01Lc, containing VP2, VP1 and 2Cmutations). In order to evaluate the lethality of the chimerical viruses,groups of 9 week- old female mice were inoculated intraperitoneally with 105pfu/mouse and monitored for 7 days. Blood samples were taken at 22 hours postinfection (hpi) for virus titration. Mice inoculated with viruses 2211Lc,2515Lc, 3688Lc, 3775Lc and 2CLc presented mild signs of disease at 48 hpi thatreverted upon 72 hpi. This phenotype was indistinguishable from that of virusesA01NLc and FMDV A01NL. Contrarily, mice inoculated with A01Lc showed severesigns of disease or even died at 48 hpi; this virus displayed the samephenotype as the parental virus FMDV A01L. Of note, mice inoculated with CapLcshowed moderate signs of disease at 48 hpi. Viral replication was evidenced at22 hpi in all groups of mice as determined by virus titration. Viremia wassignificantly higher in mice inoculated with FMDV A01L and A01Lc (p<0.05).Our results highlight the biological significance ofdiscrete genomic variations in FMDV. In particular, these results show that the4 non-synonymous changes present in the FMDV A01L capsid are sufficient toproduce signs of disease, while both capsid and 2C mutations of FMDV A01Lcontribute to the lethality of this virus in this animal model.