Pathogenic and immunologycal study of equine herpesvirus 1 infection (EHV-1).

SCROCHI MR; BRAVI ME; FUENTEALBA NA; SGUAZZA GH; NISHIDA F; CID DE LA PAZ V; GIMENO EJ; PORTIANSKY EL; BARBEITO CG; MUGLIA CI; ZANUZZI CN; GALOSI CG

Florianópolis

Congreso; XXVI Congresso Brasileiro de Virologia Y X Encontro de Virologia do Mercosul; 2015

EHV-1 causes respiratory and nervous signs, abortion and neonatal disease. In this study we performed in vitro and in vivo (BALB/c mice) assays in order to understandthe pathogenic mechanism of the abortion, and to evaluate an immunogen capable of inducing an immune response to prevent infection. In all the experiments theArgentinean AR8 strain was used. Experiment 1). We determined whether EHV-1 exerts a modulatory effect of the apoptosis during its replication cycle over: a) infected, b) non-infected and c) induced to apoptosis with sorbitol heterologous (MDBK) and homologous (ED) cell lines. Apoptosis was studied at different post-infection (pi) times using ethidium bromide and acridine orange staining (fluorescent microscopy), Annexin V FITC/ propidium iodide (flow cytometry-FC-) and transmission electron microscopy (TEM). In both infected cell lines the apoptosis was significantly lower than (c), but similar to (b); viral infection and apoptotic ultrastructural changes were confirmed by TEM. We conclude that EHV-1 interferes with the apoptosis of the infected cell lines, a strategy that may ensure virus replication. Experiment 2). We analyzed the local immune response in the uteri and placentas of intranasally infected females by day 13 of pregnancy (n=3) and the corresponding control mice(n=3). The viral isolation (VI) was carried out in lungs, uteri, placentas and fetuses taken at day 3 pi. In uteri and placentas mRNA of TNF, IFNγ and IL10 were quantified by real-time RT-PCR, and the expression of their proteins was measured by ELISA (IFNγ and IL13) or FC (TNF). The infected mice showed positive VI in their lungs, and their placentas and uteri showed a significant increase of TNF and IFNγ mRNA and protein expression, thus indicating a strong Th1 profile. In addition, a moderate increase of IL13 and IL10 was also found, possibly as a homeostatic immune response to the infection. Experiment 3). We evaluated the protective effect of apurified recombinant glycoprotein (gD) combined with the B subunit of cholera toxin (CBT) in intranasally immunized and challenged mice. Secretory IgA production was measured in upper airways lavages and plasma, and by 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 better understand the abortion pathogeny of EHV-1 infection, and to validate the new immunization strategy proposed.