Molecular detection of Rickettsia africae in Amblyomma ticks collected in cattle from Southern and Central Mozambique

open4Introduction: Rickettsia are Gram-negative and obligate intracellular bacteria, which cause typhus and spotted fever-like diseases in humans. In Africa, Rickettsia africae of the Spotted Fever Group Rickettsia (SFGR) is the etiologic agent of the African Tick-Bite Fever. The disease is transmitted by ticks of the genus Amblyomma, which serve as vectors and reservoirs of Rickettsia. In this study, we aimed to detect Rickettsia species in ticks collected from cattle in south and central Mozambique. Methodology: DNA from 412 adult ticks and 22 pools of larvae were extracted and tested for the presence of Rickettsia genes gltA, ompA and ompB by PCR, followed by sequencing and phylogenetic analysis. Results: Our results showed that in adult ticks, 79.5% (n = 330), 66% (n = 274) and 67% (n = 275) samples were positive for gltA, ompA and ompB genes, respectively. Among the 22 pools of larvae analysed, 77.2% (n = 17) were positive for the three genes tested. The infection rates ranged from 43% to 100% for Rickettsia by gltA in all locations studied, with maximum values of 100% observed in the districts of Maputo province namely Changalane, Boane and Matutuine district The phylogenetic analysis of amplified sequences revealed that samples under study grouped with R. africae for the 3 genes. Conclusion: The study showed that Spotted Fever Group Rickettsia represented by R. africae widely circulate in Ambtvomma ticks collected in south and central regions of Mozambique.openVlademiro Magaia, Elisa Taviani, Nidia Cangi, Luís NevesMagaia, Vlademiro; Taviani, Elisa; Cangi, Nidia; Neves, Luí

Recombination is a major driving force of genetic diversity in the Anaplasmataceae Ehrlichia ruminantium

The disease, Heartwater, caused by the Anaplasmataceae E. ruminantium, represents a major problem for tropical livestock and wild ruminants. Up to now, no effective vaccine has been available due to a limited cross protection of vaccinal strains on field strains and a high genetic diversity of E. ruminantium within geographical locations. To address this issue, we inferred the genetic diversity and population structure of 194 E. ruminantium isolates circulating worldwide using Multilocus Sequence Typing based on lipA, lipB, secY, sodB and sucA genes. Phylogenetic trees and networks were generated using BEAST and SplitsTree, respectively, and recombination between the different genetic groups was tested using the PHI test for recombination. Our study reveals the repeated occurrence of recombination between E. ruminantium strains, suggesting that it may occur frequently in the genome and and has likely played an important role in the maintenance of genetic diversity and the evolution of E. ruminantium. Despite the unclear phylogeny and phylogeography, E. ruminantium isolates are clustered into two main groups: Group 1 (West Africa) and a Group 2 (worldwide) which is represented by West, East and Southern Africa, Indian Ocean and Caribbean strains. Some sequence types are common between West Africa and Caribbean and between Southern Africa and Indian Ocean strains. These common sequence types highlight two main introduction events due to the movement of cattle: from West Africa to Caribbean and from Southern Africa to the Indian Ocean islands. Due to the long branch lengths between Group 1 and Group 2, and the propensity for recombination between these groups, it seems that the West African clusters of Subgroup 2 arrived there more recently than the original divergence of the two groups, possibly with the original waves of domesticated ruminants that spread across the African continent several thousand years ago

Molecular detection of Rickettsia africae in Amblyomma ticks collected in cattle from Southern and Central Mozambique

INTRODUCTION : Rickettsia are Gram-negative and obligate intracellular bacteria, which cause typhus and spotted fever-like diseases in humans. In Africa, Rickettsia africae of the Spotted Fever Group Rickettsia (SFGR) is the etiologic agent of the African Tick-Bite Fever. The disease is transmitted by ticks of the genus Amblyomma, which serve as vectors and reservoirs of Rickettsia. In this study, we aimed to detect Rickettsia species in ticks collected from cattle in south and central Mozambique. METHODOLOGY : DNA from 412 adult ticks and 22 pools of larvae were extracted and tested for the presence of Rickettsia genes gltA, ompA and ompB by PCR, followed by sequencing and phylogenetic analysis. RESULTS : Our results showed that in adult ticks, 79.5% (n = 330), 66% (n = 274) and 67% (n = 275) samples were positive for gltA, ompA and ompB genes, respectively. Among the 22 pools of larvae analysed, 77.2% (n = 17) were positive for the three genes tested. The infection rates ranged from 43% to 100% for Rickettsia by gltA in all locations studied, with maximum values of 100% observed in the districts of Maputo province namely Changalane, Boane and Matutuine district. The phylogenetic analysis of amplified sequences revealed that samples under study grouped with R. africae for the 3 genes. CONCLUSION : The study showed that Spotted Fever Group Rickettsia represented by R. africae widely circulate in Amblyomma ticks collected in south and central regions of Mozambique.This manuscript is a part of the Master thesis of VM for the Master School in Biotechnology at the Eduardo Mondlane University.This manuscript is a part of the Master thesis of VM for the Master School in Biotechnology at the Eduardo Mondlane University. VM and ET were supported by the Italian Agency for Cooperation and Development (AICS) projects AID10524 and AID11096. The study was also implemented under the framework of the GeosAf project (www.rp-pcp.org/projects/) of the African, Caribbean and Pacific (ACP) Group of States, and the authors acknowledge Dr Fernando Chanisso and Eng. Valter Nuaila for their support in the experimental work (Center for Biotechnology, Eduardo Mondlane University).The Italian Agency for Cooperation and Development (AICS)http://www.jidc.org/index.php/journalam2021Veterinary Tropical Disease

Vector-pathogen association: lack of congruence of phylogeograpical pattern of the vector tick Amblyomma variegatum (Acari: Ixodidae) and of the Ricketssiales Ehrlichia ruminantium

The hard ticks Amblyomma variegatum is the main vector of Ehrlichia ruminantium the pathogen responsible for heart water or cow driosis, a tropical disease of ruminants. This tick originates from sub-Saharan Africa and is now widely widespread. A. variegatum has been described for the first time in Madagascar in 1899, but its introduction is probably older and very likely concomitant with livestock introduction from Africa. A. variegatum has also been described in the Comoros, Mayotte, La Reunion and Mauritius islands. A. variegatum was probably introduced in the Caribbean area in the middle of the 18th century through cattle trade. Together with the tick, E. ruminantium was also introduced in these areas. Numerous and complex factors have an influence on the epidemiology of vector-borne diseases. Environmental factors, which may be deeply altered by human activities, have a direct impact on the system bacterium/vector. The creation of communication and trade routes have allowed human movements but also movement of animals, pathogens and vectors. These complex interactions may determine whether or not the vector and the pathogen would share similar phylogeographical patterns. The aim of this study was to investigate the genetic and demographic phenomena that have shaped the present distribution and structure of A. variegatum together with the bacteria E. ruminantium. A phylogeographic approached has been carried out on A. variegatum, by analysing of two mitochondrial-DNA genes and on E. ruminantium using 2 multi-locus approaches, MLST (multilocus sequence typing) on Shouskeeping genes and MLVA on 7 VNTRs (Multiple Loci VNTR Analysis). On A. variegatum, this study has led to the identification of two main lineages one covering all the species distribution area on another one restricted to East Africa and Indian Ocean area while the MLST analysis of E. ruminantium shows two main clusters, one worldwide cluster including Caribbean, Indian Ocean and West and South Africa and one restricted to West Africa. This apparent lack of congruence will be discussed according to MLVA data expected to present a higher polymorphism than MLST. (Résumé d'auteur