Pathogenic and immunologycal study of Equine Herpesvirus 1 infection (EHV-1). New insights in prophylactic strategies.

SCROCHI, M.; BRAVI, M.E.; FUENTEALBA, N.; SGUAZZA HG; NISHIDA, F.; CID DE LA PAZ V; GIMENO, E.; PORTIANSKY, E.; BARBEITO, C.; MUGLIA C.I.; ZANUZZI, C.; GALOSI, C.

Florianápolis

Congreso; Congreso; Congresso Brasileiro de Virología. X Encontro de Virología do Mercosul; 2015

Sociedad Brasilera de Virología

EHV-1causes respiratory and nervous signs, abortion and neonatal disease. In this studywe performed in vitro and in vivo (BALB/c mice) assays in order tounderstand the pathogenic mechanism of the abortion, and to evaluate animmunogen capable of inducing an immune response to prevent infection. In all theexperiments the Argentinean AR8 strain was used. Experiment 1). Wedetermined whether EHV-1 exerts a modulatory effect of the apoptosis during itsreplication cycle over: a) infected, b) non-infected and c) inducedto apoptosis with sorbitol heterologous(MDBK) and homologous (ED) cell lines. Apoptosis was studied at different post-infection (pi) timesusing ethidium bromide and acridine orange staining (fluorescent microscopy), AnnexinV FITC/propidium iodide (flow cytometry-FC-) and transmission electronmicroscopy (TEM). In both infected cell lines the apoptosis was significantlylower than(c), but similar to (b);viral infection and apoptotic ultrastructural changes were confirmed by TEM. Weconclude that EHV-1 interferes with the apoptosis of the infected cell lines, astrategy that may ensure virus replication. Experiment 2). We analyzed thelocal immune response in the uteri and placentas of intranasally infectedfemales by day 13 of pregnancy (n=3) and the corresponding control mice (n=3). Theviral isolation (VI) was carried out in lungs, uteri, placentas and fetusestaken at day 3 pi. In uteri and placentas mRNA of TNF, IFNγ and IL10 werequantified by real-time RT-PCR, and the expression of their proteins was measuredby ELISA (IFNγ and IL13) or FC (TNF). The infected mice showed positive VI intheir lungs, and their placentas and uteri showed a significant increase of TNFand IFNγ mRNA and protein expression, thus indicating a strong Th1 profile. Inaddition, a moderate increase of IL13 and IL10 was also found, possibly as ahomeostatic immune response to the infection. Experiment 3). We evaluated theprotective effect of a purified recombinant glycoprotein (gD) combined with theB subunit of cholera toxin (CBT) in intranasally immunized and challenged mice.Secretory IgA production was measured in upper airways lavages and plasma, andby immunohistochemistry in lungs. IgA was detected in the lungs of immunized mice.The use of gD and CBT prevented the arrival of the virus to the lungs. These results provide new data to betterunderstand the abortion pathogeny of EHV-1 infection, and to validate the newimmunization strategy proposed