Delivery of SA35 and SA40 peptides in mice enhances humoral and cellular immune responses and confers protection against Cryptosporidium parvum infection

Abstract

Background 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. 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. Methods Adult 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 × 10 5 and 5 × 10 3 ) of C. parvum oocysts and the parasitic burden was determined at 5 and 9 days post-infection. Results Intraperitoneal 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 × 10 5 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 × 10 3 oocysts. Conclusions SA35 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.

Vaccine development for cryptosporidiosis: Systematic review

“…Also, a significant reduction in the excretion of oocysts eliminated in the feces of these animals was noted (Askari et al, 2016). In mice, this immunization has also been observed, resulting in a marked reduction in the intestinal parasitic burden of puppies infected with C. parvum, with mothers previously inoculated with SA35 and SA40 antigens, intranasally (Tosini et al, 2019).…”

“…The recombinant protein CpSushi has an immunoprotective effect, with a reduction of 68.91% elimination of oocysts in the feces of mice challenged with Cryptosporidium tyzzeri (Huang et al, 2017). Recombinant peptides SA35 and SA40, portions of two C. parvum proteins, improve humoral and cell-mediated immune responses in adult mice (Tosini et al, 2019).…”

“…In neonates, passive immunization may be an alternative to a conventional vaccine. In the case of newborn calves, ingestion of colostrum plays a significant role in the control and prevention of the disease (Askari et al, 2016;Tosini et al, 2019).…”

“…The study of the structural and functional characteristics of the candidate antigens for the synthesis of an effective immunogen is essential (Yang et al, 2016), since commercial vaccines are not available for animal or human protection or as mechanisms to prevent environmental contamination (Tomazic et al, 2018;Tosini et al, 2019).…”

Controlled Human Infection Models To Accelerate Vaccine Development

“…A very large and heavily glycosylated protein, called gp900, is under consideration because it binds to intestinal epithelial cells and inhibits C. parvum attachment in vitro. An antigenic fragment of gp900 (designated SA40), as well as a fragment of another antigenic sporozoite protein, Cpa135 (designated SA35), were determined to have a protective effect as maternal antigens in a BALB/c neonatal mouse model (547). The second approach to Cryptosporidium vaccines is the use of reverse genetics to identify potential target antigens.…”