Dataset Information

MHC-associated Baylisascaris schroederi load informs the giant panda reintroduction program.

ABSTRACT: Reintroducing captive giant pandas (Ailuropoda melanoleuca) to the wild is the ultimate goal of their ex situ conservation. Choosing higher fitness candidates to train prior to release is the first step in the giant panda reintroduction program. Disease resistance is one important index of individual fitness and presumed to be related to variation at major histocompatibility complex genes (MHC). Here, we used seven polymorphic functional MHC genes (Aime-C, Aime-I, Aime-L, Aime-DQA1, Aime-DQA2, Aime-DQB1 and Aime-DRB3) and estimate their relationship with Baylisascaris schroederi (Ascarididae) infection in giant panda. We found that DQA1 heterozygous pandas were less frequently infected than homozygotes. The presence of one MHC genotype and one MHC allele were also associated with B. schroederi infection: Aime-C*0203 and Aime-L*08 were both associated with B. schroederi resistance. Our results indicate that both heterozygosity and certain MHC variants are important for panda disease resistance, and should therefore be considered in future reintroduction programs for this species alongside conventional selection criteria (such as physical condition and pedigree-based information).

SUBMITTER: Zhu Y

PROVIDER: S-EPMC7283101 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature

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MHC-associated Baylisascaris schroederi load informs the giant panda reintroduction program.

Zhu Ying Y Grueber Catherine C Li Yudong Y He Ming M Hu Lan L He Ke K Liu Hongyi H Zhang Hemin H Wu Honglin H

International journal for parasitology. Parasites and wildlife 20200528

Reintroducing captive giant pandas (Ailuropoda melanoleuca) to the wild is the ultimate goal of their ex situ conservation. Choosing higher fitness candidates to train prior to release is the first step in the giant panda reintroduction program. Disease resistance is one important index of individual fitness and presumed to be related to variation at major histocompatibility complex genes (MHC). Here, we used seven polymorphic functional MHC genes (Aime-C, Aime-I, ...[more]

PMID: 32528846

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Project description:BackgroundInfection with the parasitic nematode, Baylisascaris schroederi (Ascaridida: Nematoda), is one of the most important causes of death in giant pandas, and was responsible for half of deaths between 2001 and 2005. Mitochondrial (mt) DNA sequences of parasites can unveil their genetic diversity and depict their likely dynamic evolution and therefore may provide insights into parasite survival and responses to host changes, as well as parasite control.MethodsBased on previous studies, the present study further annotated the genetic variability and structure of B. schroederi populations by combining two different mtDNA markers, ATPase subunit 6 (atp6) and cytochrome c oxidase subunit I (cox1). Both sequences were completely amplified and genetically analyzed among 57 B. schroederi isolates, which were individually collected from ten geographical regions located in three important giant panda habitats in China (Minshan, Qionglai and Qinling mountain ranges).ResultsFor the DNA dataset, we identified 20 haplotypes of atp6, 24 haplotypes of cox1, and 39 haplotypes of atp6 + cox1. Further haplotype network and phylogenetic analyses demonstrated that B. schroederi populations were predominantly driven by three common haplotypes, atp6 A1, cox1 C10, and atp6 + cox1 H11. However, due to low rates of gene differentiation between the three populations, both the atp6 and cox1 genes appeared not to be significantly associated with geographical divisions. In addition, high gene flow was detected among the B. schroederi populations, consistent with previous studies, suggesting that this parasite may be essentially homogenous across endemic areas. Finally, neutrality tests and mismatch analysis indicated that B. schroederi had undergone earlier demographic expansion.ConclusionsThese results confirmed that B. schroederi populations do not follow a pattern of isolation by distance, further revealing the possible existence of physical connections before geographic separation. This study should also contribute to an improved understanding of the population genetics and evolutionary biology of B. schroederi and assist in the control of baylisascariasis in giant pandas.

Project description:BackgroundBaylisascaris schroederi, an intestinal nematode of the giant panda, is the cause of the often fatal disease, baylisascariasis. Glutathione S-transferases (GSTs) are versatile enzymes that can affect parasite survival and parasite-host interactions and, are therefore, potential targets for the development of diagnostic tests and vaccines.MethodsIn this study, we identified a full-length cDNA that encoded a novel, secretory sigma-like GST (Bsc-GSTσ) from a B. schroederi-omic dataset. Following cloning and sequencing, sequence and structural analyses and comparative modeling were performed using online-bioinformatics and proteomics tools. The recombinant Bsc-GSTσ (rBsc-GSTσ) protein was prokaryotically expressed and then used to detect antigenicity and reactivity using immunoblotting assays. In addition, the native protein in female adult B. schroederi was located via immunofluorescence techniques, while the preliminary ELISA-based serodiagnostic potential of rBsc-GSTσ was assessed in native and infected mouse sera.ResultsBsc-GSTσ contained a 621-bp open reading frame that encoded a polypeptide of 206 amino acids with two typical sigma GST domain profiles, including a GST_N_Sigma_like at the N-terminus and a GST_C_Sigma_like at the C-terminus. The presence of an N-terminal signal sequence indicated that Bsc-GSTσ was a secretory protein. Sequence alignment and phylogenetic analyses showed that Bsc-GSTσ was a nematode-specific member of the Sigma class GSTs and shared the closest genetic distance with its homologue in Ascaris suum. Further comparative structure analyses indicated that Bsc-GSTσ possessed the essential structural motifs (e.g., βαβαββα) and the consensus secondary or tertiary structure that is typical for other characterized GSTσs. Immunolocalization revealed strong distributions of native Bsc-GSTσ in the body hypodermis, lateral chords, gut epithelium, gut microvilli, oviduct epithelium, and ovaries of adult female worms, similar to its homologue in A. suum. Building on good immunogenic properties, rBsc-GSTσ-based ELISA exhibited a sensitivity of 79.1% and a specificity of 82.0% to detect anti-B. schroederi IgG antibodies in the sera of experimentally infected mice.ConclusionThis study presents a comprehensive demonstration of sequence and structural-based analysis of a new, secretory sigma-like GST from a nematode, and its good serodiagnostic performance suggests that rBsc-GSTσ has the potential to detect B. schroederi and, therefore, could be used to develop an ELISA-based serological test to diagnose baylisascariasis in giant pandas.

Project description:BackgroundBaylisascaris schroederi is one of the most common nematodes of the giant panda, and can cause severe baylisascarosis in both wild and captive giant pandas. Previous studies of the giant pandas indicated that this population is genetically distinct, implying the presence of a new subspecies. Based on the co-evolution between the parasite and the host, the aim of this study was to investigate the genetic differentiation in the B. schroederi population collected from giant pandas inhabiting different mountain ranges, and further to identify whether the evolution of this parasite correlates with the evolution of giant pandas.MethodsIn this study, 48 B. schroederi were collected from 28 wild giant pandas inhabiting the Qinling, Minshan and Qionglai mountain ranges in China. The complete sequence of the mitochondrial cytochrome b (mtCytb) gene was amplified by PCR, and the corresponding population genetic diversity of the three mountain populations was determined. In addition, we discussed the evolutionary relationship between B. schroederi and its host giant panda.ResultsFor the DNA dataset, insignificant Fst values and a significant, high level of gene flow were detected among the three mountain populations of B. schroederi, and high genetic variation within populations and a low genetic distance were observed. Both phylogenetic analyses and network mapping of the 16 haplotypes revealed a dispersed pattern and an absence of branches strictly corresponding to the three mountain range sampling sites. Neutrality tests and mismatch analysis indicated that B. schroederi experienced a population expansion in the past.ConclusionsTaken together, the dispersed haplotype map, extremely high gene flow among the three populations of B. schroederi, low genetic structure and rapid evolutionary rate suggest that the B. schroederi populations did not follow a pattern of isolation by distance, indicating the existence of physical connections before these populations became geographically separated.

Project description:BackgroundBaylisascaris schroederi is the most common and harmful intestinal parasitic nematode of giant pandas, causing ascariasis. Although drug deworming is the main measure to control ascariasis in captive giant pandas, prolonged and repeated use of deworming drugs might induce resistance in nematodes and drug residues in giant pandas. Therefore, developing a safe and effective vaccine might provide a novel strategy to prevent ascariasis in captive giant pandas.MethodsFour highly expressed secretome genes encoding excretory and secretory proteins of B. schroederi, including transthyretin-like protein 46 (BsTLP), uncharacterized protein (BsUP), hypothetical protein 1 (BsHP1), and hypothetical protein 2 (BsHP2) and four functional genes [(encoding Galectin (BsGAL), glutathione S-transferase (BsGST), fatty acid-binding protein (BsFABP), and thioredoxin peroxidase (BsTPX)] were identified based on genome and transcriptome databases of B. schroederi and used to construct recombinant proteins via prokaryotic expression. Kunming mice were vaccinated subcutaneously twice with the recombinant proteins (50 μg/mouse) mixed with Quil A adjuvant with a 2-week interval and then orally challenged with 3000 infective eggs. The immunoprotective effects of the eight recombinant proteins on mice were assessed comprehensively using surface lesion histology scores of the mouse liver and lung, larval worm reduction, serum antibody levels (IgG, IgE, IgA, IgG1, and IgG2a), and cytokine production [interferon gamma (IFN-γ), interleukin (IL)-2, IL-4, IL-5, and IL-10].ResultsMice vaccinated with recombinant (r)BsUP (76.5%), rBsGAL (74.7%), and rBsHP2 (71.5%) showed a significant (P < 0.001) reduction in the larval worm rate compared with that in the adjuvant control. Besides, the surface lesions in the liver and lung of the vaccinated mice were alleviated. Serum levels of total IgG, IgE, IgA, IgG1, IgG2a, and cytokines, including IL-10, IL-5, and IFN-γ, were significantly higher (P < 0.001) than those in the control group.ConclusionsThe results showed that candidate three vaccines (rBsUP, rBsGAL, and rBsHP2) could provide effective protection against egg infection in mice associated with a mixed Th1/2-type immune response.

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MHC-associated Baylisascaris schroederi load informs the giant panda reintroduction program.

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MHC-associated <i>Baylisascaris schroederi</i> load informs the giant panda reintroduction program.

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