On the Biological and Genetic Diversity in Neospora caninum

Abstract

Neospora caninum is a parasite regarded a major cause of foetal loss in cattle. A key requirement to an understanding of the epidemiology and pathogenicity of N. caninum is knowledge of the biological characteristics of the species and the genetic diversity within it. Due to the broad intermediate host range of the species, worldwide geographical distribution and its capacity for sexual reproduction, significant biological and genetic differences might be expected to exist. N. caninum has now been isolated from a variety of different host species including dogs and cattle. Although isolates of this parasite show only minor differences in ultrastructure, considerable differences have been reported in pathogenicity using mainly mouse models. At the DNA level, marked levels of polymorphism between isolates were detected in mini-and microsatellites found in the genome of N. caninum. Knowledge of what drives the biological differences that have been observed between the various isolates at the molecular level is crucial in aiding our understanding of the epidemiology of this parasite and, in turn, the development of efficacious strategies, such as live vaccines, for controlling its impact. The purpose of this review is to document and discuss for the first time, the nature of the diversity found within the species Neospora caninum.

Neospora caninum in bovine fetuses of Minas Gerais, Brazil: genetic characteristics of rDNA

“…Following the study by Payne and Ellis (1996), relating to the DNA region that codes for rRNA of N. caninum, several other studies have been published. However, in specifically analyzing the ITS-1 region, few studies have demonstrated nucleotide variations (AL-QASSAB et al, 2010). Similar findings were reported by Santos et al (2010), using sequences deposited in GenBank.…”

“…However, the sequences obtained in this study referring to this region remained unchanged. This conservation of sequences probably occurred because of control over the mutagenic pressure, influenced by the immunity complex (AL-QASSAB et al, 2010). This conservation was reflected in the phylogenetic tree, which was characterized by presenting a single grouping of N. caninum, without distinguishing the geographical origin or type of host.…”

“…Thus, new investigations in other gene regions of N. caninum are needed in order to confirm whether this conservation is normal in the genome of the parasite, or whether there are any gene regions that would be more appropriate for phylogenetic studies. Since knowledge of the genetic characteristics of N. caninum is still being acquired, and because this protozoon has only relatively recently been described (DUBEY et al, 1988), together with the small number of sequences deposited in GenBank, this field of research is completely open to investigation (AL-QASSAB et al, 2010).…”

“…The gene region ITS-1 has become the target for phylogenetic studies, since this region experiences greatest mutagenic evolutionary pressure and is subject to polymorphism (PAYNE and ELLIS, 1996;AL-QASSAB et al, 2009;AL-QASSAB et al, 2010;SANTOS et al, 2010). Despite these studies, there are still few gene sequences of ITS-1 deposited in GenBank, including those originating from Brazil.…”

On the Efficacy and Safety of Vaccination with Live Tachyzoites of Neospora caninum for Prevention of Neospora-Associated Fetal Loss in Cattle

“…Neospora caninum is a protozoan parasite first identified in dogs but now mostly recognized as being associated with fetal death and abortion in midterm pregnant cattle (1). Although canids such as dogs and dingoes are known to be definitive hosts for this parasite (2), the main form of transmission among cattle is transplacental in utero from the dam to its fetus.…”