Cat-rodent Toxoplasma gondii Type II-variant circulation and limited genetic diversity on the Island of Fernando de Noronha, Brazil

Jean Carlos Ramos Silva,Juliana Aizawa,Thais Ferreira Feitosa,Hilda Fátima Jesus Pena,Rinaldo Aparecido Mota,Solange Maria Gennari,Fernando Jorge Rodrigues Magalhães,Maria Fernanda Vianna Marvulo,Jitender Prakask Dubey,Carlos Diógenes Ferreira Lima Filho,Fernando Ferreira,Daniel Ajzenberg,Solange Oliveira,Herbert Sousa Soares,Leucio Câmara Alves,Ricardo Augusto Dias

doi:10.1186/s13071-017-2150-4

Abstract

BackgroundIn Brazil, studies on animals and humans in mainland areas have shown that most strains of Toxoplasma gondii are pathogenic to mice and exhibit great genetic variability.ResultsIn this study, using a set of 11 PCR-RFLP and 15 microsatellite markers, we isolated and genetically characterised T. gondii strains from one cat and three rats on Fernando de Noronha Island. The cat had antibodies to T. gondii, which were revealed using a modified agglutination test (MAT, cut-off 1:25) and the seroprevalence among the 46 rodents was 15.2%. Viable T. gondii was isolated from one cat (TgCatBrFN1), two brown rats (TgRatnoBrFN1 and TgRatnoBrFN2) and one black rat (TgRatraBrFN1). Unlike the strains from mainland Brazil, these isolates were not pathogenic to outbred mice. The genotypes of these strains were compared with strains previously isolated on the island and in mainland Brazil. The analysis based on microsatellite data showed a limited genetic diversity of T. gondii on Fernando de Noronha Island with the majority of strains clustered into the following three groups: type II, III, and Caribbean 1.ConclusionsThere was little variation among strains within the same group, suggesting that the majority of strains circulating on Fernando de Noronha are derived from only a few strains that were recently introduced to the island, likely from imported cats. Except for the strain belonging to the Caribbean 1 group that originates from northeast Brazil, there was little evidence that strains from the other groups were introduced to Fernando de Noronha via mainland Brazil.

Highlights

In Brazil, studies on animals and humans in mainland areas have shown that most strains of Toxoplasma gondii are pathogenic to mice and exhibit great genetic variability
Toxoplasma gondii strains isolated from chickens, cats, and cattle egrets on Fernando de Noronha showed unexpected genotyping results. These results showed the presence of atypical genotypes that seemed endemic to the island as well as clonal type II strains that are common in Europe and North America but are virtually absent in mainland Brazil [3, 9, 10]
The objective of this study was to isolate and characterise T. gondii strains from one cat and several rodents on Fernando de Noronha with PCR-FLP and microsatellite markers and examine their genetic relationships with other strains previously isolated on the island and in mainland Brazil

Summary

Introduction

In Brazil, studies on animals and humans in mainland areas have shown that most strains of Toxoplasma gondii are pathogenic to mice and exhibit great genetic variability. Toxoplasma gondii infections are prevalent in animals and humans on a global level [1]. The worldwide genetic diversity of T. gondii isolates has been studied extensively over the last two decades, showing that the hotspot of diversity is located in South America, in Brazil [4]. Fernando de Noronha (3°50'28.9''S, 32°24'39.4''W) is an archipelago of 21 islands and islets in the Atlantic Ocean and is located approximately 354 km east of the Brazilian coast. There are no records regarding the juncture of when cats and rats were introduced to the island, but these animals may have come from Europe on ships that arrived on the archipelago, starting at the time of its first human occupation during the sixteenth century

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