Immune responses during pregnancy in heifers naturally infected with Neospora caninum with and without immunization.
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: The course of anti-Neospora antibody kinetics during two consecutive pregnancies has been evaluated in five chronically in-fected dairy cows. The blood samples of cows were collected monthly. Anti-Neospora antibodies in blood sera were detected by indirect ELISA (ID-VET, France). During whole period of the study cows remained seropositive; with S/P% values (iELISA) ranging from 94 to 214%. The antibody kinetics determined by iELISA showed a significant increase (P<0.0059) of specific IgG antibodies in the third trimester of both pregnancies. The monitored cows gave birth to 10 healthy calves (4 steers and 6 heifers). To confirm the occurrence of vertical transmission of Neospora from mothers to offspring in the herd, dam-daugh-ter serology was performed. Anti-Neospora antibodies was found in 4 from 6 heifers (>6 months old). Study presents original data reporting on the very similar persistent pattern of anti-Neospora antibody levels during the third trimester of pregnancies in all five dairies. Based on the high seropositivity of female offspring, the reactivation of a latent infection of cows rather than a re-infection can be supposed.Acta Parasitologica 11/2013; 58(4):463–467. · 1.00 Impact Factor
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ABSTRACT: Neospora caninum is an intracellular apicomplexan parasite, which is a leading cause of abortion in cattle; thus neosporosis represents an important veterinary health problem and is of high economic significance. The parasite can infect cattle via trans-placental transmission from an infected cow to its fetus (vertical transmission), or through the oral route via ingestion of food or water contaminated with oocysts that were previously shed with the feces of a canid definitive host (horizontal transmission). Although vaccination was considered a rational strategy to prevent bovine neosporosis, the only commercialized vaccine (Neoguard®) produced ambiguous results with relatively low efficacy, and was recently removed from the market. Therefore, there is a need to develop an efficient vaccine capable of preventing both, the horizontal transmission through infected food or water to a naïve animal as well as the vertical transmission from infected but clinically asymptomatic dams to the fetus. Different vaccine strategies have been investigated, including the use of live attenuated vaccines, killed parasite lysates, total antigens or antigen fractions from killed parasites, and subunit vaccines. The vast majority of experimental studies were performed in mice, and to a certain extent in gerbils, but there is also a large number of investigations that were conducted in cattle and sheep. However, it is difficult to directly compare these studies due to the high variability of the parameters employed. In this review, we will summarize the recent advances made in vaccine development against Neospora caninum in cattle and in mice and highlight the most important factors, which are likely to influence the degree of protection mediated by vaccination.Experimental Parasitology 03/2014; · 2.15 Impact Factor
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ABSTRACT: The aim of this study was to determine the transmission paths of Neospora caninum in a dairy herd of crossbred cattle. Two hundred and ninety animals were grouped according to the year of their birth to verify the distribution of infection according to age. The blood of 196 cattle was collected thrice, with an average interval of 210 days, to evaluate the existence of horizontal transmission in the herd. To evaluate vertical transmission, the blood of 64 calves was collected prior to ingestion of colostrum and from their mothers at parturition. Moreover, 63 family trees were built. The presence of anti-N. caninum antibodies was detected using an indirect fluorescent antibody test. The chi-square test (χ(2)) with Yates' correction or Fisher's exact test was used to evaluate the relation between the serology and age groups and between the serostatus of cows and their progeny in different calvings. A higher seropositivity (p=0.035) was found in animals born in 2008 compared to those born in 1997-2007. The serological status of only 13 animals presented changes, of which six (3.1%) became seropositive, indicating a low proportion of horizontal transmission. All seropositive cows gave birth to seropositive calves, resulting in 100% vertical transmission. Sixty-three family trees were constructed. In 29 (46%) of these families, there were animals seropositive for N. caninum. Congenital infection in relation to the number of births was estimated from the relation of Mother+ and Daughter+, without significant differences (p=0.84) between the number of births and the transmission of the parasite from infected cows to their progeny. The low proportion of horizontal transmission combined with the high proportion of vertical transmission allowed us to conclude that transplacental transmission is the principal route of N. caninum infection in the herd.Veterinary Parasitology 01/2014; · 2.38 Impact Factor