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

Tosini, Fabio, Ludovisi, Alessandra, Tonanzi, Daniele, Amati, Marco, Cherchi, Simona, Pozio, Edoardo, Gómez-Morales, Maria Angeles
Parasites & vectors 2019 v.12 no.1 pp. 233
Cryptosporidium parvum, adults, blood serum, cell-mediated immunity, children, diarrhea, females, immune response, immunization, immunoglobulin A, immunoglobulin G, interferon-gamma, intestinal mucosa, maternal immunity, mice, neonates, oocysts, parasite load, peptides, pregnancy, recombinant antigens, ruminants, splenocytes
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 × 10⁵ and 5 × 10³) 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 × 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. 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.