Abstract
BackgroundCryptosporidium parvum is a major cause of diarrhea in children and ruminants at the earliest stages of life. Maternal antibodies represent the main shield of neonate mammals for most of the infections. Two recombinant antigens (SA35 and SA40), portions of two C. parvum proteins, were tested for their ability to induce immune responses in adult mice and for protection on neonate BALB/c mice born from females immunised by mucosal delivery of both peptides.MethodsAdult BALB/c mice were intraperitoneally immunised with SA35 and SA40, separately or mixed, and their immune response was characterised. Furthermore, BALB/c pregnant mice were immunised by mucosal delivery with an SA35/40 mix, before and during pregnancy. Soon after birth, their offspring were infected with two doses (1 × 105 and 5 × 103) of C. parvum oocysts and the parasitic burden was determined at 5 and 9 days post-infection.ResultsIntraperitoneal immunisation with SA35 and SA40 induced specific IgG and IgG1 in serum, specific IgA in the intestinal mucosa, increase of CD3+/CD4+ and CD30+ cells in splenocytes, which produced IFN-γ. Neonates born from immunised mice and infected with 1 × 105 oocysts showed a significant reduction of oocysts and intestinal forms (23 and 42%, respectively). A reduction of all parasitic forms (96%; P < 0.05) was observed when neonates were infected with 5 × 103 oocysts.ConclusionsSA35 and SA40 peptides induce specific humoral and cell-mediated immune responses to C. parvum in adult mice. Moreover, mucosal administration of the SA35/40 mix in pregnant mice reduces C. parvum burden in their litters.
Highlights
Cryptosporidium parvum is a major cause of diarrhea in children and ruminants at the earliest stages of life
A recent study on diarrhoea conducted on calves younger than one month reported that C. parvum is responsible, as the sole agent, for 37% of diarrhoeal infections and for 20% of coinfections with other intestinal pathogens [6]
Specific anti-Cryptosporidium IgA were detected in sera from day 7 after initial immunisation, and slightly increased until day 35 p.i. (U(0) = 2, Z = −2.50672; for SA35 and SA35/40 mix, P = 0.0079, for SA40, P = 0.0159; Fig. 2 Kinetics of the IgG (a), IgG1 (b) and IgA (c) responses to Cryptosporidium parvum-crude extract (CCE) in BALB/c mouse sera. d Kinetics of the IgA responses to CCE in BALB/c mouse faecal content
Summary
Cryptosporidium parvum is a major cause of diarrhea in children and ruminants at the earliest stages of life. Maternal antibodies represent the main shield of neonate mammals for most of the infections. Oocysts are highly resistant to environmental conditions, chlorination and other sterilisation treatments, and contamination of water plants can cause massive outbreaks [4]. It follows that the Food and Agriculture Organisation and the World Health Organisation consider protozoa of the genus Cryptosporidium to be one of the most significant food-borne parasites [5]. C. parvum is a major cause of severe diarrhoea among neonate calves and lambs, resulting in substantial costs for farmers. A recent study on diarrhoea conducted on calves younger than one month reported that C. parvum is responsible, as the sole agent, for 37% of diarrhoeal infections and for 20% of coinfections with other intestinal pathogens [6]
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