Real-time PCR detection and phylogenetic relationships of Neorickettsia spp. in digeneans from Egypt, Philippines, Thailand, Vietnam and the United States

Abstract

Neorickettsia (Rickettsiales, Anaplasmataceae) is a genus of obligate intracellular bacterial endosymbionts of digeneans (Platyhelminthes, Digenea). Some Neorickettsia are able to invade cells of the digenean's vertebrate host and are known to cause diseases of domestic animals, wildlife, and humans. In this study we report the results of screening digenean samples for Neorickettsia collected from bats in Egypt and Mindoro Island, Philippines, snails and fishes from Thailand, and fishes from Vietnam and the USA. Neorickettsiae were detected using a real-time PCR protocol targeting a 152 bp fragment of the heat shock protein coding gene, GroEL, and verified with nested PCR and sequencing of a 1853 bp long region of the GroESL operon and a 1371 bp long region of 16S rRNA. Eight unique genotypes of Neorickettsia were obtained from digenean samples. Neorickettsia sp. 8 obtained from Lecithodendrium sp. from Egypt; Neorickettsia sp. 9 and 10 obtained from two species of Paralecithodendrium from Mindoro, Philippines; Neorickettsia sp. 11 from Lecithodendrium sp. and Neorickettsia sp. 4 (previously identified from Saccocoelioides lizae, from China) from Thailand; Neorickettsia sp. 12 from Dicrogaster sp. Florida, USA; Neorickettsia sp. 13 and SF agent from Vietnam. Sequence comparison and phylogenetic analysis demonstrated that the forms, provisionally named Neorickettsia sp. 8-13, represent new genotypes. We have for the first time detected Neorickettsia in a digenean from Egypt (and the African continent as a whole), the Philippines, Thailand and Vietnam based on PCR and sequencing evidence. Our findings suggest that further surveys from the African continent, SE Asia, and the Island countries are likely to reveal new Neorickettsia lineages as well as new digenean host associations.

Nanophyetus salmincola, vector of the salmon poisoning disease agent Neorickettsia helminthoeca, harbors a second pathogenic Neorickettsia species

“…Second, this is only the second report of a single digenean species serving as the host for more than one Neorickettsia species; the first such record was N. salmincola harboring EFF (Farrell et al, 1973). This demonstrates the possibility of host-switching among species of Neorickettsia , especially considering the high host specificity of Neoricekttsia (Tkach et al, 2012, Greiman et al, 2014; Greiman et al, in press). The most interesting, however, is the potential role of different Neorickettsia species as agents of dog diseases.…”

Transcriptomic responses of Biomphalaria pfeifferi to Schistosoma mansoni: Investigation of a neglected African snail that supports more S. mansoni transmission than any other snail species

“…pfeifferi transcripts found were bacteria with most belonging to the genera Escherichia , Mycoplasma , Aeromonas , and Pseudomonas ( Fig 5 ). Among them, a CDS with homology to Neorickettsia sp , a known obligatory symbiont of digenetic trematodes [ 83 ], was recovered and has read counts >10 in 2 of our samples that also had relatively high counts of S . mansoni (3d-R3 and shedding-R1) ( Table 1 ; S2 File ).…”

Analysis of complete genome sequence and major surface antigens of Neorickettsia helminthoeca, causative agent of salmon poisoning disease

“…As endosymbionts of digenetic trematodes (parasitic flatworms or flukes), Neorickettsia species are abundant in nature and have been identified throughout the life cycle of the trematodes and the hosts of trematodes including the essential first intermediate host of snails, the second intermediate hosts such as fish and aquatic insects and the definitive hosts such as mammals and birds wherein the trematodes sexually reproduce fertilized eggs (Cordy and Gorham, ; Philip et al ., ,b; Philip, ; Foreyt et al ., ; Gibson et al ., ; Rikihisa et al ., ; Gibson and Rikihisa, ; Greiman et al ., ). Recent reports revealed more than 10 new genotypes of Neorickettsia in divergent digenean families throughout the world, including Asia, Africa, Australia, Americas and even Antarctica (Ward et al ., ; Tkach et al ., ; Greiman et al ., , ), suggesting a global distribution of Neorickettsia spp. Notably, a Neorickettsia sp.…”