MLVA16 Typing of Portuguese Human and Animal Brucella melitensis and Brucella abortus Isolates

Ana Cristina Ferreira,Lídia Flor,Rogério Tenreiro,Teresa Pacheco,Gilles Vergnaud,Isabel Travassos Dias,Maria Inácia Corrêa De Sá,Tania Tenreiro,Bruno Garin-Bastuji,Regina Cardoso,Philippe Le Flèche,Lélia Chambel,Axel Cloeckaert

doi:10.1371/journal.pone.0042514

Abstract

To investigate the epidemiological relationship of isolates from different Portuguese geographical regions and to assess the diversity among isolates, the MLVA16Orsay assay (panels 1, 2A and 2B) was performed with a collection of 126 Brucella melitensis (46 human and 80 animal isolates) and 157 B. abortus field isolates, seven vaccine strains and the representative reference strains of each species. The MLVA16Orsay showed a similar high discriminatory power (HGDI 0.972 and 0.902) for both species but panel 1 and 2A markers displayed higher diversity (HGDI 0.693) in B. abortus compared to B. melitensis isolates (HGDI 0.342). The B. melitensis population belong to the “Americas” (17%) and “East Mediterranean” (83%) groups. No isolate belonged to the “West Mediterranean” group. Eighty-five percent of the human isolates (39 in 46) fit in the “East-Mediterranean” group where a single lineage known as MLVA11 genotype 116 is responsible for the vast majority of Brucella infections in humans. B. abortus isolates formed a consistent group with bv1 and bv3 isolates in different clusters. Four MLVA11 genotypes were observed for the first time in isolates from S. Jorge and Terceira islands from Azores. From the collection of isolates analysed in this study we conclude that MLVA16Orsay provided a clear view of Brucella spp. population, confirming epidemiological linkage in outbreak investigations. In particular, it suggests recent and ongoing colonisation of Portugal with one B. melitensis lineage usually associated with East Mediterranean countries.

Highlights

Brucellosis is a worldwide zoonotic disease caused by Brucella, a gram-negative alphaproteobacteria that infects a wide range of mammal including domestic and wild animals as well as humans [1]
In this report we present the results of a study performed by Brucella MLVA16Orsay on 283 human and animal field isolates of B. melitensis and B. abortus
The MLVA16Orsay assay was performed with a collection of 126 B. melitensis (46 human and 80 animals) and 157 B. abortus isolates, 7 vaccine strains and the representative reference strains of each species (Table 1, Figure 1)

Summary

Introduction

Brucellosis is a worldwide zoonotic disease caused by Brucella, a gram-negative alphaproteobacteria that infects a wide range of mammal including domestic and wild animals as well as humans [1]. There are ten recognized species of Brucella based on phenotypic and antigenic differences, differential host specificity and genetic diversity. The classical Brucella species were: B. abortus (cattle); B. melitensis (sheep and goats); B. ovis (sheep); B. canis (dogs); B. suis (pigs, wild boars, hares, reindeer and caribou) and B. neotomae (rodent) [2]. In three species biovars are recognized, B. abortus (1–6, 9), B. melitensis (1–3) and B. suis (1–5) [6]. B. abortus is the most disseminated species worldwide and B. melitensis produces the most severe infection in humans and predominates in the Mediterranean Basin [7]

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