rROP2 from Toxoplasma gondii as a potential vaccine against oocyst shedding in domestic cats

Abstract

The aim of the present study was to evaluate oocyst shedding in cats immunized by nasal route with T. gondii proteins ROP2. Twelve short hair cats (Felis catus) were divided in three groups G1, G2 and G3 (n=4). Animals from G1 received 100 μg of rROP2 proteins plus 20 μg of Quil-A, G2 received 100 μg of BSA plus 20 μg of Quil-A, and the G3 only saline solution (control group). All treatments were done by intranasal route at days 0, 21, 42, and 63. The challenge was performed in all groups on day 70 with ≅ 800 tissue cysts of ME-49 strain by oral route. Animals from G1 shed less oocysts (86.7%) than control groups. ELISA was used to detect anti-rROP2 IgG and IgA, however, there were no correlation between number of oocyst shedding by either IgG or IgA antibody levels. In the present work, in spite of lesser oocysts production in immunized group than control groups, it was not possible to associate the use of rROP2 via nostrils with protection against oocyst shedding. For the future, the use of either other recombinant proteins or DNA vaccine, in combination with rROP2 could be tested to try improving the efficacy of this kind of vaccine.

Protection against Toxoplasma gondii cysts in pigs immunized with rROP2 plus Iscomatrix

“…In the present study, we observed pigs immunized with rROP2 + Iscomatrix by IN did not show systemic antibody response; however, after IM inoculation, they raised all immunoglobulins, which we associated to partial protection against the high dose of T. gondii oocyst challenge. Although pigs from our study did not show a humoral response after intranasal immunization, previous studies have demonstrated pigs and cats produced IgG and IgM antibodies after vaccination with crude and recombinant ROP2 proteins of T. gondii (Cunha et al, 2012;Zulpo et al, 2012Zulpo et al, , 2017. Kringel et al (2004) used tachyzoites from the RH strain plus CpG-oligodeoxynucleotides to infect pigs and observed 10 times more anti-T. gondii IgG from the immunized pigs.…”

Use of Veterinary Vaccines for Livestock as a Strategy to Control Foodborne Parasitic Diseases

“…Despite these discouraging conclusions, a few researches in vaccine development against T. gondii infection targeted to cats have been done, including the subcutaneous immunization with live Co-irradiated tachyzoites of T. gondii Beverley strain (Omata et al, 1996 ), oral immunization with ME49 strain tissue cysts (Freyre et al, 2007 ) or with T. gondii T-263 strain cysts (Frenkel et al, 1991 ) or bradyzoites (Freyre et al, 1993 ; Mateus-Pinilla et al, 1999 ). Additionally, subunit vaccines including as antigens ROP2 (Mishima et al, 2002 ; Zulpo et al, 2017 ) or crude rhoptry proteins (García et al, 2007 ; Zulpo et al, 2012 ) were also tested. However, with the exception of T-263 strain vaccine, none of the previously mentioned formulations completely prevented oocyst-shedding in the tested animals.…”

Promising Plant-Derived Adjuvants in the Development of Coccidial Vaccines

“…The ability to elicit this type of immune response makes it ideal for use in vaccines directed against intracellular pathogens, such as coccidial parasites (48). In fact, Quil A has been administered as a mucosal adjuvant against toxoplasmosis in subunit vaccines including as antigens crude rhoptry proteins of T. gondii (58, 59, 64) or recombinant ROP2 (54, 60). These formulations were evaluated in different host species, including cats (54, 58, 64), pigs (59) and mice (60), resulting in enhanced humoral (58–60) and cellular immune responses (59) but, at best, in partial protection against infection (59, 60, 64).…”