Article

Immune responses during pregnancy in heifers naturally infected with Neospora caninum with and without immunization.

Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, 1 Shields Avenue, Davis, CA 95616, USA.
Parasitology Research (Impact Factor: 2.85). 05/2005; 96(1):24-31. DOI: 10.1007/s00436-005-1313-y
Source: PubMed

ABSTRACT This study was designed to identify changes in parasite-specific immune responses that occur during vertical transmission of Neospora caninum and can be used as indicators of parasite reactivation in naturally infected heifers. Ten heifers were unimmunized and 11 immunized with killed tachyzoites. One unimmunized heifer, which aborted at week 19 of gestation, had an increase in parasite-specific antibodies, mainly IgG(2), from week 15 to week 19 and a concomitant decline in parasite-specific cell-mediated immune (CMI) responses. Eight unimmunized heifers, which had live full-term congenitally infected calves, had an increase in antibodies, mainly IgG(2), from week 21 onwards. All immunized heifers delivered live full-term congenitally infected calves, and had a bimodal increase in antibodies; primarily IgG(1) following immunization and predominantly IgG(2) from week 17 onwards. Immunized heifers had significantly greater overall mean humoral and CMI responses than unimmunized heifers. Nine uninfected control heifers and their calves were seronegative. These results indicate that reactivation of a latent infection occurred in the naturally infected heifers, regardless of their immunization status, and was associated with increased parasite-specific antibodies, mainly IgG(2).

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    ABSTRACT: I parassiti, e in particolare quelli di natura protozoaria, rientrano tra le principali cause di malattia, sia negli animali che nell’uomo. La presente ricerca è stata finalizzata alla messa a punto di un modello in vitro per lo studio dei primi eventi che si verificano in seguito all’infezione da parte di un protozoo. I parassiti scelti per la presente ricerca sono stati Neospora caninum, organismo molto simile a Toxoplasma gondii ma che ha importanza esclusivamente veterinaria, essendo causa di aborto nella specie bovina e Leishmania infantum, protozoo agente della leishmaniosi viscerale nel cane e nell’uomo (zoonotico). Il modello cellulare scelto era invece la cellula presentante l’antigene, ed è stato analizzato con diversi strumenti: la linea istiocitaria di cane DH82, i macrofagi di bovino e le cellule dendritiche di bovino e di cane, queste ultime generate dal sangue periferico con o senza l’impiego di citochine ricombinanti. La dimostrazione che tali parassiti possono infettare questi tipi cellulari, insieme allo studio di alcune alterazioni dei recettori di superficie, potrà fornirà le basi per una migliore comprensione dell’immunopatogenesi delle malattie parassitarie, per le quali si è ancora lontani da traguardi già ottenuti in altri settori della medicina, quali la vaccinazione nelle malattie infettive. Parasites, mainly protozoa, represent one of the main cause of disease both in animals and man. Present research focused on the establishment of an in vitro model of the first events that follow the infection with a protozoon. Neospora caninum, an organism closely related to Toxoplasma gondii of exclusive veterinary interest being a bovine abortifacient and Leishmania infantum, zoonotic agent of visceral leishmaniosis, are the parasites chosen for the present study. The cellular model chosen for this study was instead Antigen presenting cell(s), and it was analyzed using several instruments: a continuous canine histiocytic cell line (DH82), bovine machrophages and bovine/canine Dendritic cells (DCs). DCs were generated from peripheral blood with or without recombinant cytokines. The results reported here demonstrate that the considered parasites are able to infect the antigen presenting cells involved in the present study. Also, in the present study it has been performed an evaluation of the consequences of the infection in terms of cell surface markers expression. These findings constitute some basic knowledge that will be useful for the study of immunopathogenesis of parasitic diseases. In this field some goals already achieved in other fields of medicine (e.g. vaccination in infectious diseases) are urgently needed.
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