Genetic variability of Taenia solium cysticerci recovered from experimentally infected pigs and from naturally infected pigs using microsatellite markers

First Insights into Population Structure and Genetic Diversity Versus Host Specificity in Trypanorhynch Tapeworms Using Multiplexed Shotgun Genotyping

Theory predicts relaxed host specificity and high host vagility should contribute to reduced genetic structure in parasites while strict host specificity and low host vagility should increase genetic structure. Though these predictions are intuitive, they have never been explicitly tested in a population genomic framework. Trypanorhynch tapeworms, which parasitize sharks and rays (elasmobranchs) as definitive hosts, are the only order of elasmobranch tapeworms that exhibit considerable variability in their definitive host specificity. This allows for unique combinations of host use and geographic range, making trypanorhynchs ideal candidates for studying how these traits influence population-level structure and genetic diversity. Multiplexed shotgun genotyping (MSG) data sets were generated to characterize component population structure and infrapopulation diversity for a representative of each trypanorhynch suborder: the ray-hosted Rhinoptericola megacantha (Trypanobatoida) and the shark-hosted Callitetrarhynchus gracilis (Trypanoselachoida). Adults of R. megacantha are more host-specific and less broadly distributed than adults of C. gracilis, allowing correlation between these factors and genetic structure. Replicate tapeworm specimens were sequenced from the same host individual, from multiple conspecific hosts within and across geographic regions, and from multiple definitive host species. For R. megacantha, population structure coincided with geography rather than host species. For C. gracilis, limited population structure was found, suggesting a potential link between degree of host specificity and structure. Conspecific trypanorhynchs from the same host individual were found to be as, or more, genetically divergent from one another as from conspecifics from different host individuals. For both species, high levels of homozygosity and positive FIS values were documented.

Genetic structure of Spirometra mansoni (Cestoda: Diphyllobothriidae) populations in China revealed by a Target SSR-seq method

BACKGROUND

In China, the plerocercoid of the cestode Spirometra mansoni is the main causative agent of human and animal sparganosis. However, the population genetic structure of this parasite remains unclear. In this study, we genotyped S. mansoni isolates with the aim to improve current knowledge on the evolution and population diversity of this cestode.

METHODS

We first screened 34 perfect simple sequence repeats (SSRs) using all available omic data and then constructed target sequencing technology (Target SSR-seq) based on the Illumina NovaSeq platform. Next, a series of STRUCTURE. clustering, principal component, analysis of molecular variance and TreeMix analyses were performed on 362 worm samples isolated from 12 different hosts in 16 geographical populations of China to identify the genetic structure.

RESULTS

A total of 170 alleles were detected. The whole population could be organized and was found to be derived from the admixture of two ancestral clusters. TreeMix analysis hinted that possible gene flow occurred from Guizhou (GZ) to Sichuan (SC), SC to Jaingxi (JX), SC to Hubei (HB), GZ to Yunnan (YN) and GZ to Jiangsu (JS). Both neighbor-joining clustering and principal coordinate analysis showed that isolates from intermediate hosts tend to cluster together, while parasites from definitive hosts revealed greater genetic differences. Generally, a S. mansoni population was observed to harbor high genetic diversity, moderate genetic differentiation and a little genetic exchange among geographical populations.

CONCLUSIONS

A Target SSR-seq genotyping method was successfully developed, and an in-depth view of genetic diversity and genetic relationship will have important implications for the prevention and control of sparganosis.

Genetic Variation of Taenia Saginata Cyst Isolates from Iraq Based on Mitochondrial COX1 Sequences

The zoonotic parasite disease of economic and public health relevance is bovine cysticercosis, resulting from the larval stage of Taenia saginata. The presented research aims to identify intraspecific variation in T. saginata isolated from cattle in Iraq's Sulaymaniyah province using the mitochondrial cytochrome c oxidase subunit 1 (COX1) gene. Sequence analysis of the COX1 gene revealed that five distinct haplotypes were identified in 37 T. saginata specimens from Iraq. Four of the five T. saginata haplotypes may have been identified for the first time in the world. Phylogenetic research revealed that all T. saginata haplotypes had been clustered in a single clade, with Korean and Iranian isolates sharing a high degree of closeness. In addition, individual haplotypes related to COX1 had a pairwise evolutionary divergence of 0.005- 0.013, whereas the overall evolutionary divergence regarding all five haplotypes ranged between 0.000-0.018. It was concluded that added newly recorded data on T. saginata genetic variation could have substantial implications for taeniasis epidemiology and control.

Existence of genetic lineages within Asian genotype of Taenia solium-Genetic characterization based on mitochondrial and ribosomal DNA markers

Taenia solium cysticercosis is a potentially eradicable neglected zoonotic disease with public health importance. The genetic lineages of T. solium in Asia and Africa/America are distinct and the genetic composition of the parasite was found to influence the clinical symptoms in patients with cysticercosis. In the present study, the Cysticerci collected from pigs of two southern states of India (Karnataka and Andhra Pradesh) were genetically characterized based on mitochondrial (COX 1 and Cyt b) and ribosomal (ITS-1 and TBR) DNA markers. The study confirms the existence of two mitochondrial lineages of the parasite as Asian and African/American. Cytochrome oxidase 1 (COX 1) based analysis revealed the existence of two sub-lineages of the parasite within the Asian lineage based on the polymorphism at 994 position as 994A/G. In India, both the sub-lineages were identified and genetic divergence among different Indian isolates was evident. Further, the sequence analysis of Cytochrome B (Cyt b) revealed the existence of six sub-lineages of T. solium in India as 69T/69G, 97A/97G as well as 264T/264C. The analysis of nucleotide sequence of large subunit ribosomal DNA (TBR) revealed the existence of two sub-lineages in India based on the deletion of a nucleotide at 624^th position. The cysts collected in the present study were more closely related to those of China and Indonesia than with other Indian isolates. Further, the sequence analysis did not indicate the presence of Taenia asiatica in the examined pigs and African/American lineages of T. solium. The results of the present study help to better understand the genetic diversity of T. solium in India.

Development of multi-epitope chimeric vaccine against Taenia solium by exploring its proteome: an in silico approach

Objective: Taenia solium is a neglected tropical disease; larvae of this parasite infect central nervous system i.e. Neurocysticercosis, and adults mature and survive into intestine i.e. Taeniasis. Globally more than 50 million people are at the risk of infection. This is one of the main etiological agents for onset of new early epilepsy in developing countries. However, there is no vaccine available to protect human from its infection. Hence, there is an urgent need for a good vaccine.Methods: We applied immune-informatics approach to design a multi-epitope chimeric vaccine consisting of both B and T-cell epitopes.Results: From the whole transcriptome of Taenia, we identified five suitable peptides present on cell membrane, epitope identification on these peptides were done by using various immunoinformatic software. Physiochemical properties were determined and the tertiary structure of vaccine was predicted, validated and refined, and to increase antigenicity we added linker to them. Best-modeled protein-complex was used for docking study with TLR1-2, TLR4, TLR3 and TLR7 and stability of molecular complex was determined by molecular dynamics simulation.Conclusions: Overall, we attempted to design an efficient subunit chimeric vaccine, which could stimulate humoral and cellular immune responses and could protect against both neurocysticercosis and taeniasis.

Genetic Characterization of Taenia saginata Cyst Isolates from Germany

The beef tapeworm Taenia saginata, which causes taeniosis in humans and cysticercosis in cattle, is of medical and economic importance. Understanding the parasite's genetic population structure may help to analyze transmission patterns and aid in the development of control measures. As information on sequence variability is scarce for European isolates, this study aimed to elucidate the intraspecific genetic variability of T. saginata cysts from German cattle by sequence comparison of the mitochondrial cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 5 (nad5) genes, in relationship to sequences from other geographical origins. Cysts were collected from northern German, Swiss, and Belgian cattle. Moreover, proglottids from an adult T. saginata specimen from Palestine were included. Amplification and Sanger sequencing of the cox1 gene was successful for 57 samples (45 German, 9 Swiss, 2 Belgian, 1 Palestinian), whereas 32 sequences were obtained for the nad5 gene (21 German, 10 Swiss, 1 Palestinian). For German isolates, sequence comparison revealed minor genetic variability with two polymorphic sites and mutations in both genes. Three haplotypes with haplotype diversity of 0.088 for cox1 and 0.186 for nad5, as well as nucleotide diversities of 0.00028 and 0.00095, respectively, were observed. Comparison of the cox1 gene sequence of German isolates with other European, African, American, and Asian isolates obtained from National Center for Biotechnology Information (total of 71 sequences) raised 11 polymorphic sites and mutations as well as 10 haplotypes (haplotype diversity: 0.239; nucleotide diversity: 0.00097). Although nad5 sequence comparison comprised less sequences (N = 33), analyses revealed 11 polymorphic sites, 12 mutation sites, and 7 haplotypes (haplotype diversity: 0.335, nucleotide diversity: 0.00391), indicating a better resolution of genetic variability compared to cox1. Thus, nad5 may be particularly useful for in-depth studies on genetic divergence of T. saginata.