2 METHODS
2.1
Protocols
The Preferred Reporting Items for Systematic Reviews and Meta-Analyses
(PRISMA) were followed in order to systematically review 30
cross-sectional studies. The whole methodological protocol of this study
was registered on OSF with DOI 10.17605/OSF.IO/FJU94 and might be
accessed by the link https://osf.io/fju94/.
2.2 Systematic search
strategy
Four English Databases were used including Scopus , PubMed ,ScienceDirect and Web of Science , for literature searching
of articles published prior to September 21st, 2020.
All scientific publications related to genetic characterization ofT. gondii isolated from free-range chickens (Gallus gallus
domesticus ) were sought.
The terms used in the searching process were “toxoplasmosis”,
“Toxoplasma gondii ”, “T. gondii ”, “type”,
“typing”, “genotype”, “genotyping”, “molecular
characterization”, “chicken”, “fowl”, “pould” and “RFLP”. Only
studies published in English were considered. All citations were
imported to Mendeley (by Elsevier) and the studies were tabulated on
Sheets (by GSuite – Google). Further studies were checked by scanning
the reference list of the selected papers to prevent missing valuable
data.
2.3 Study selection
criteria
The papers were screened independently by three reviewers. The studies
were selected as they corresponded to inclusion criteria, and those
which did not contemplate the requirements were excluded. Duplicated
articles and review works were excluded from the process. The main
inclusion criteria was the presence of genotypes of T. gondiiisolated strictly from free-range chickens (Gallus gallus
domesticus) in experimental works, which was observed in the titles and
abstracts or full texts, if necessary.
Thus, articles about seroprevalence, diagnostic methods, or those which
did not perform the genotyping of their isolates using RFLP-PCR and did
not present a table showing their markers along the result of ToxoDB #
genotype or clonal type, were excluded. Studies that used less than 5
markers were not included (Amouei et al., 2020).
2.4 Data
extraction
Data from all of the selected articles were extracted independently
according to PRISMA checklist standardized form developed for molecular
studies by trained data extractors. Data contemplated general
characteristics: first author, year of publication and country; and
methodological characteristics: sample size, tissue location, host (only
free-range chickens), examination techniques used to identify infected
hosts (MAT, IFAT, ELISA, PCR, Nested-PCR, bioassays), number of DNA
isolates, number of genotypes/types/clonal types, and ToxoDB #
evidenced.