INDUCTION OF EARLY SPECIFIC LOCAL IMMUNE RESPONSES IN THE RESPIRATORY TRACT OF FMD-INFECTED CATTLE

PEGA, JUAN FRANCO; BUCAFUSCO, DANILO; DI GIACOMO, SEBASTIÁN; PÉREZ-BEASCOECHEA, CLAUDIA; STAFFORINI, GUILLERMINA; COMPAIRED, DIEGO; MARADEI, EDUARDO; RODRÍGUEZ, LUIS; BORCA, MANUEL VÍCTOR; PÉREZ FILGUEIRA, MARIANO

Viena

Congreso; Open session of the Standing Technical Committee of the EuFMD Commission; 2010

The European Commission for the control of Foot-and-Mouth disease (EuFMD)

Cattle are highly susceptible to FMDV infection via the respiratory tract  and induction of local mucosal immune responses should be among the first reactions to  the infection. Here, we present preliminary data describing these early steps of the  adaptive response in cattle infected by controlled aerosol exposure. Also, progression of  clinical signs and induction of systemic adaptive responses were compared between  aerosol vs. needle infected cattle.  Four FMDV antibody-negative animals were used: 2 were infected with FMDV O1 Campos by the oronasal route, 1 by intradermolingual inoculation and 1 was kept as non-infected control.  FMDV-specific antibody secreting cells (ASC) from lymphoid tissues of the respiratory  tract were identihed by ELISpot assay at 3 and 6 days post-infection (dpi). Systemic  antibodies were determined by lpELISA and virus seroneutralization test.  Clinical signs of FMDV infection were observed starting at 2 dpi in all infected  animals. At 3 dpi, no specific immune responses were detected at local or systemic levels.  At 6 dpi, FMDV-specific ASC were detected in mandibular lymph nodes (MLN), medial and  lateral retropharyngeal lymph nodes (MRPLN and LRPLN), pharyngeal tonsils,  tracheobronchial lymph nodes (TBLN) and spleen. All immunoglobulin isotypes were  identified, but there was a clear predominance of IgM. MLN were the most reactive  organs, followed by TBLN and mRPLN. Systemic antibody responses started at 5 dpi and  were similar in aerosol and needle infected animals. Non·lnfected animal did not show  FMDV-speciGc immune responses.   Local adaptive responses were detected all along the respiratory tract in the  aerosol-infected animal euthanized at 6 dpi. Immunoglobulin profiles corresponded to a  primary response, with IgM the most prevalent isotype followed by IgG1, IgA and IgG2.  FMDV-specific ASC were very prevalent, accounting for 0.22% and 0.12% of the total  lymphoid cells in MLN and TBLN, respectively.