Serologic and molecular diagnostic and bioassay in mice for detection of Toxoplasma gondii in free ranges chickens from Pantanal of Mato Grosso do Sul

Abstract

The aim of this study was to investigate the occurrence of Toxoplasma gondii and compare the results obtained in the Modiϐied Agglutination Test (MAT), Polimerase Chain Reaction (PCR) and bioassay in mice. In order to accomplish this, 40 free-range chickens from eight farms in neighboring areas to the Pantanal in Nhecolândia, Mato Grosso do Sul, were euthanized and blood samples, brain and heart were collected. The occurrence of anti-T. gondii antibodies found in chickens was 67.5% (27 samples), considering as a cutoff point the dilution 1:5. Among the samples analyzed, 7 (25.9%) were positive in the dilution 1:5, 3 (11.1%) in 1:10, 2 (7.4%) in 1:20, 3 (11.1%) in 1:320, 1 ( 3.7%) in 1:640, 3 (11.1%) in 1:1280, 2 (7.4%) in 1:2560, 4 (14.8%) in 1:5120 and 2 (7.4%) in 1:10.240. From the mixture of tissue samples (brain and heart) from the chickens analyzed, 16 (40%) presented electrophoretic bands compatible with T. gondii by PCR (gene B1). In the comparison of techniques, 59.26% positivity in PCR was revealed among animals that were seropositive in MAT (cutoff 1:5). From 141 inoculated mice, six (4.44%) died of acute toxoplasmosis between 15 and 23 days after inoculation. Surviving mice were sacriϐiced at 74 days after inoculation, and a total of 28 cysts were found in the brains of 10 distinct groups. From the seropositive hens, 27 bioassays were performed and 11 (40.7%) isolates were obtained. A greater number of isolations happened in mice that were inoculated with tissues from chickens that had high titers for anti-T. gondii antibodies. Chronic infection in mice was observed in nine groups (33.3%) from ϐive different properties. Among the surviving mice, 25.6% were positive for T. gondii in MAT (1:25). From mice positive in PCR, 87.5% were also positive in MAT. Among the PCR-negative mice, 5.2% were positive for T. gondii in MAT. It can be concluded through this study that the occurrence of infecton by T. gondii in the rural properties studied was high, that PCR directed to gene B1 does not conϐirm the viability of the parasite, but it can be used as a screening method for the selection of chickens infected by T. gondii, that the animals with titer greater than 10 must be prioritized for the selection of animals for bioassay, since for them, the chances of isolating the parasite are greater and that seroconversion in experimentally infected mice is not a good indicator for isolating the agent.

Occurrence of anti-Toxoplasma gondii antibodies and parasite DNA in backyard chicken breeding in Northeast, Brazil

“…In Brazil, 70% of people have been exposed to T. gondii at some point in their lives (VERGARA et al, 1985). Indeed, serological studies conducted in different regions of the country have reported prevalence rates ranging from 11.18% to 78.7% (JAMRA & GUIMARÃES, 1981;FERRARONI & LACAZ, 1982;ABRAHAMS-SANDI & VARGAS-BRENES, 2005;HOLSBACK et al, 2012;ZHAO et al, 2012;IBRAHIM et al, 2014).…”

Toxoplasma gondii in milk of naturally infected dairy ewes on west mesoregion of Santa Catarina state, Brazil

“…Still, Rosa et al (2001) and Trevisani (2013) found that mice inoculated, even with cysts on SNC and/or tachyzoites not seroconverted, while others were seropositive (IFA 1:16) without the detection of tissue cysts (Trevisani, 2013). Divergences between results of isolation agent by bioassay and serology of the inoculated mice were also observed by Holsback et al (2012) and Cademartori et al (2014).…”

Infection rate by TOXOPLASMA GONDII in free-range and broiler chickens in the states of Rio Grande do Norte and Paraíba, Brazil

“…Analyzing the reactivity index (RI) of the samples tested by ELISA, the distribution of positive samples was concentrated between RI values ≥1 and <2. On none of the properties did the chickens have excessively high titers, as observed in previous studies (Holsback et al, 2012;Vieira et al, 2018). Through experimental infection of domestic chickens, a progressive decrease in antibody titers after reaching a peak at 35 days after infection with antibodies still detectable by direct agglutination at 63 days after infection (Galli et al, 2008).…”