Immunoreactive Protein Repertoires of Ehrlichia chaffeensis and E. canis Reveal the Dominance of Hypothetical Proteins and Conformation-dependent Antibody Epitopes

2021 ◽  
Author(s):  
Tian Luo ◽  
Jignesh G. Patel ◽  
Xiaofeng Zhang ◽  
David H. Walker ◽  
Jere W. McBride
Keyword(s):  
Immune Responses ◽  
Hypothetical Protein ◽  
Ehrlichia Chaffeensis ◽  
Hypothetical Proteins ◽  
Significant Group ◽  
Molecular Features ◽  
A Genome ◽  
Species Specific ◽  
Protective Proteins ◽  
Antibody Epitopes

The immunomes of Ehrlichia chaffeensis ( E. ch. ) and E. canis ( E. ca. ) have recently be revised to include immunodominant hypothetical proteins with conformational antibody epitopes. In this study, we examined 216 E. ch. and 190 E. ca. highly antigenic proteins according to ANTIGENpro and also performed a genome-wide hypothetical protein analysis ( E. ch. n=104; E. ca. n=124) for immunoreactivity. Using cell-free protein expression and immunoanalysis, 118 E. ch. and 39 E. ca . proteins reacted with sera from naturally E. ch. -infected patients or E. ca. -infected dogs. Moreover, 22 E. ch. and 18 E. ca. proteins consistently and strongly reacted with a panel of patient or canine sera. A subset of E. ch. (n=18) and E. ca. (n=9) proteins were identified as immunodominant. Consistent with our previous study, most proteins were classified as hypothetical and the antibody epitopes exhibited complete or partial conformation-dependence. The majority (28/40; 70%) of E. ch. and E. ca. proteins contained transmembrane domains and 19 (48%) were predicted to be secreted effectors. The antigenic repertoires of E. ch. and E. ca. were mostly diverse and suggest that the immunomes of these closely related ehrlichiae are dominated by species-specific conformational antibody epitopes. This study reveals a significant group of previously undefined E. ch. and E. ca. antigens and reaffirms the importance of conformation-dependent epitopes as targets of anti- Ehrlichia immune responses. These findings substantially expand our understanding of host- Ehrlichia immune responses, advance efforts to define the molecular features of protective proteins and improve prospects for effective vaccines for the ehrlichioses.

scholarly journals Ehrlichia chaffeensis and E. canis hypothetical protein immunoanalysis reveals small secreted immunodominant proteins and conformation-dependent antibody epitopes

npj Vaccines ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Tian Luo ◽  
Jignesh G. Patel ◽  
Xiaofeng Zhang ◽  
David H. Walker ◽  
Jere W. McBride
Keyword(s):  
Tandem Repeat ◽  
Gold Standard ◽  
Hypothetical Protein ◽  
Bioinformatic Analysis ◽  
Ehrlichia Chaffeensis ◽  
Hypothetical Proteins ◽  
Repeat Proteins ◽  
Tandem Repeat Proteins ◽  
Antibody Epitopes

Abstract Immunomolecular characterization of Ehrlichia chaffeensis (E. ch.) and E. canis (E. ca.) has defined protein orthologs, including tandem repeat proteins (TRPs) that have immunodominant linear antibody epitopes. In this study, we combined bioinformatic analysis and cell-free protein expression to identify undiscovered immunoreactive E. ch. and E. ca. hypothetical proteins. Antigenicity of the E. ch. and E. ca. ORFeomes (n = 1105 and n = 925, respectively) was analyzed by the sequence-based prediction model ANTIGENpro, and we identified ~250 ORFs in each respective ORFeome as highly antigenic. The hypothetical proteins (E. ch. n = 93 and E. ca. n = 98) present in the top 250 antigenic ORFs were further investigated in this study. By ELISA, 46 E. ch. and 30 E. ca. IVTT-expressed hypothetical proteins reacted with antibodies in sera from naturally E. ch.-infected patients or E. ca.-infected dogs. Moreover, 15 E. ch. and 16 E. ca. proteins consistently reacted with a panel of sera from patients or dogs, including many that revealed the immunoreactivity of “gold standard” TRPs. Antibody epitopes in most (>70%) of these proteins exhibited partial or complete conformation-dependence. The majority (23/31; 74%) of the major immunoreactive proteins identified were small (≤250 aa), and 20/31 (65%) were predicted to be secreted effectors. Unlike the strong linear antibody epitopes previously identified in TRP and OMP orthologs, there were contrasting differences in the E. ch. and E. ca. antigenic repertoires, epitopes and ortholog immunoreactivity. This study reveals numerous previously undefined immunodominant and subdominant antigens, and illustrates the breadth, complexity, and diversity of immunoreactive proteins/epitopes in Ehrlichia.

scholarly journals Major Species-Specific Antibody Epitopes of the Ehrlichia chaffeensis p120 and E. canis p140 Orthologs in Surface-Exposed Tandem Repeat Regions

2009 ◽  
Vol 16 (7) ◽  
pp. 982-990 ◽  
Author(s):  
Tian Luo ◽  
Xiaofeng Zhang ◽  
Jere W. McBride
Keyword(s):  
Tandem Repeat ◽  
Posttranslational Modifications ◽  
Molecular Characteristics ◽  
Small Subset ◽  
Ehrlichia Chaffeensis ◽  
Flight Mass Spectrometry ◽  
Major Species ◽  
Molecular Masses ◽  
Species Specific ◽  
Antibody Epitopes

ABSTRACT Ehrlichia chaffeensis and E. canis have a small subset of tandem repeat (TR)-containing protein orthologs, including p120/p140, which elicit strong antibody responses. The TR regions of these protein orthologs are immunoreactive, but the molecular characteristics of the p120/p140 epitopes have not been determined. In this study, the immunodeterminants of the E. chaffeensis p120 and E. canis p140 were identified and molecularly defined. Major antibody epitope-containing regions of both p120 and p140 were localized to the TR regions, which reacted strongly by Western immunoblotting with antibodies in sera from E. chaffeensis-infected dogs or patients and E. canis-infected dogs, respectively. Single continuous species-specific major epitopes within the E. chaffeensis p120 and E. canis p140 TRs were mapped to homologous surface-exposed glutamate/aspartate-rich regions (19 to 22 amino acids). In addition, minor cross-reactive epitopes were localized to homologous N- and C-terminal regions of p120 and p140. Furthermore, although the native and recombinant p120 and p140 proteins exhibited higher-than-predicted molecular masses, posttranslational modifications were not present on abnormally migrating p120 and p140 TR recombinant proteins as determined by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

scholarly journals A Variable-Length PCR Target Protein of Ehrlichia chaffeensis Contains Major Species-Specific Antibody Epitopes in Acidic Serine-Rich Tandem Repeats

2008 ◽  
Vol 76 (4) ◽  
pp. 1572-1580 ◽  
Author(s):  
Tian Luo ◽  
Xiaofeng Zhang ◽  
Abdul Wakeel ◽  
Vsevolod L. Popov ◽  
Jere W. McBride
Keyword(s):  
Tandem Repeats ◽  
Variable Length ◽  
Small Subset ◽  
Ehrlichia Chaffeensis ◽  
Host Immune Responses ◽  
Amino Acid Region ◽  
Infected Cells ◽  
Recombinant Polypeptides ◽  
Species Specific ◽  
Antibody Epitopes

ABSTRACT Ehrlichia chaffeensis and E. canis have a small subset of tandem repeat (TR)-containing proteins that elicit strong host immune responses and are associated with host-pathogen interactions. In a previous study, we molecularly characterized a highly conserved 19-kDa major immunoreactive protein (gp19) of E. canis and identified the corresponding TR-containing ortholog variable-length PCR target (VLPT) protein in E. chaffeensis. In this study, the native 32-kDa VLPT protein was identified and the immunodeterminants defined in order to further understand the molecular basis of the host immune response to E. chaffeensis. Synthetic and/or recombinant polypeptides corresponding to various regions of VLPT were used to localize major antibody epitopes to the TR-containing region. Major antibody epitopes were identified in three nonidentical repeats (R2, R3, and R4), which reacted strongly with antibodies in sera from an E. chaffeensis-infected dog and human monocytotropic ehrlichiosis patients. VLPT-R3 and VLPT-R2 reacted most strongly with antibody, and the epitope was further localized to a nearly identical proximal 17-amino-acid region common between these repeats that was species specific. The epitope in R4 was distinct from that of R2 and R3 and was found to have conformational dependence. VLPT was detected in supernatants from infected cells, indicating that the protein was secreted. VLPT was localized on both reticulate and dense-core cells, and it was found extracellularly in the morula fibrillar matrix and associated with the morula membrane.

scholarly journals Signatures of conserved and unique molecular features in Afrotheria

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Arangasamy Yazhini ◽  
Narayanaswamy Srinivasan ◽  
Sankaran Sandhya
Keyword(s):  
Ribosomal Proteins ◽  
Individual Species ◽  
Functional Domain ◽  
Nucleic Acid Binding ◽  
Uncharacterized Protein ◽  
Homologous Proteins ◽  
Functional Roles ◽  
Molecular Features ◽  
Specific Proteins ◽  
Species Specific

AbstractAfrotheria is a clade of African-origin species with striking dissimilarities in appearance and habitat. In this study, we compared whole proteome sequences of six Afrotherian species to obtain a broad viewpoint of their underlying molecular make-up, to recognize potentially unique proteomic signatures. We find that 62% of the proteomes studied here, predominantly involved in metabolism, are orthologous, while the number of homologous proteins between individual species is as high as 99.5%. Further, we find that among Afrotheria, L. africana has several orphan proteins with 112 proteins showing < 30% sequence identity with their homologues. Rigorous sequence searches and complementary approaches were employed to annotate 156 uncharacterized protein sequences and 28 species-specific proteins. For 122 proteins we predicted potential functional roles, 43 of which we associated with protein- and nucleic-acid binding roles. Further, we analysed domain content and variations in their combinations within Afrotheria and identified 141 unique functional domain architectures, highlighting proteins with potential for specialized functions. Finally, we discuss the potential relevance of highly represented protein families such as MAGE-B2, olfactory receptor and ribosomal proteins in L. africana and E. edwardii, respectively. Taken together, our study reports the first comparative study of the Afrotherian proteomes and highlights salient molecular features.

scholarly journals Characterization of the Major Antigenic Protein 2 of Ehrlichia canis and Ehrlichia chaffeensis and Its Application for Serodiagnosis of Ehrlichiosis

2003 ◽  
Vol 10 (4) ◽  
pp. 520-524 ◽  
Author(s):  
Tamece T. Knowles ◽  
A. Rick Alleman ◽  
Heather L. Sorenson ◽  
David C. Marciano ◽  
Edward B. Breitschwerdt ◽  
...  
Keyword(s):  
Blot Analysis ◽  
Single Copy ◽  
Ehrlichia Canis ◽  
Specific Method ◽  
Ehrlichia Chaffeensis ◽  
Antigenic Protein ◽  
Canine Monocytic Ehrlichiosis ◽  
Copy Gene ◽  
Species Specific

ABSTRACT Canine monocytic ehrlichiosis, caused by Ehrlichia canis or Ehrlichia chaffeensis, can result in clinical disease in naturally infected animals. Coinfections with these agents may be common in certain areas of endemicity. Currently, a species-specific method for serological diagnosis of monocytic ehrlichiosis is not available. Previously, we developed two indirect enzyme-linked immunosorbent assays (ELISAs) using the major antigenic protein 2 (MAP2) of E. chaffeensis and E. canis. In this study, we further characterized the conservation of MAP2 among various geographic isolates of each organism and determined if the recombinant MAP2 (rMAP2) of E. chaffeensis would cross-react with E. canis-infected dog sera. Genomic Southern blot analysis using digoxigenin-labeled species-specific probes suggested that map2 is a single-copy gene in both Ehrlichia species. Sequences of the single map2 genes of seven geographically different isolates of E. chaffeensis and five isolates of E. canis are highly conserved among the various isolates of each respective ehrlichial species. ELISA and Western blot analysis confirmed that the E. chaffeensis rMAP2 failed to serologically differentiate between E. canis and E. chaffeensis infections.

scholarly journals Going Wild: Lessons from Naturally Occurring T-Lymphotropic Lentiviruses

2006 ◽  
Vol 19 (4) ◽  
pp. 728-762 ◽  
Author(s):  
Sue VandeWoude ◽  
Cristian Apetrei
Keyword(s):  
Immune Responses ◽  
Natural Populations ◽  
Host Immune Responses ◽  
Experimental Systems ◽  
Naturally Occurring ◽  
Immunodeficiency Virus ◽  
New Directions ◽  
Species Specific ◽  
Lentiviral Infections ◽  
Hiv Aids

SUMMARY Over 40 nonhuman primate (NHP) species harbor species-specific simian immunodeficiency viruses (SIVs). Similarly, more than 20 species of nondomestic felids and African hyenids demonstrate seroreactivity against feline immunodeficiency virus (FIV) antigens. While it has been challenging to study the biological implications of nonfatal infections in natural populations, epidemiologic and clinical studies performed thus far have only rarely detected increased morbidity or impaired fecundity/survival of naturally infected SIV- or FIV-seropositive versus -seronegative animals. Cross-species transmissions of these agents are rare in nature but have been used to develop experimental systems to evaluate mechanisms of pathogenicity and to develop animal models of HIV/AIDS. Given that felids and primates are substantially evolutionarily removed yet demonstrate the same pattern of apparently nonpathogenic lentiviral infections, comparison of the biological behaviors of these viruses can yield important implications for host-lentiviral adaptation which are relevant to human HIV/AIDS infection. This review therefore evaluates similarities in epidemiology, lentiviral genotyping, pathogenicity, host immune responses, and cross-species transmission of FIVs and factors associated with the establishment of lentiviral infections in new species. This comparison of consistent patterns in lentivirus biology will expose new directions for scientific inquiry for understanding the basis for virulence versus avirulence.

scholarly journals Rotavirus A Genome Segments Show Distinct Segregation and Codon Usage Patterns

Viruses ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1460
Author(s):  
Irene Hoxie ◽  
John J. Dennehy
Keyword(s):  
Immune Responses ◽  
Codon Usage ◽  
Host Species ◽  
Phylogenetic Trees ◽  
Translational Efficiency ◽  
Rotavirus A ◽  
A Genome ◽  
Usage Patterns ◽  
Dsrna Genome ◽  
Codon Deoptimization

Reassortment of the Rotavirus A (RVA) 11-segment dsRNA genome may generate new genome constellations that allow RVA to expand its host range or evade immune responses. Reassortment may also produce phylogenetic incongruities and weakly linked evolutionary histories across the 11 segments, obscuring reassortment-specific epistasis and changes in substitution rates. To determine the co-segregation patterns of RVA segments, we generated time-scaled phylogenetic trees for each of the 11 segments of 789 complete RVA genomes isolated from mammalian hosts and compared the segments’ geodesic distances. We found that segments 4 (VP4) and 9 (VP7) occupied significantly different tree spaces from each other and from the rest of the genome. By contrast, segments 10 and 11 (NSP4 and NSP5/6) occupied nearly indistinguishable tree spaces, suggesting strong co-segregation. Host-species barriers appeared to vary by segment, with segment 9 (VP7) presenting the weakest association with host species. Bayesian Skyride plots were generated for each segment to compare relative genetic diversity among segments over time. All segments showed a dramatic decrease in diversity around 2007 coinciding with the introduction of RVA vaccines. To assess selection pressures, codon adaptation indices and relative codon deoptimization indices were calculated with respect to different host genomes. Codon usage varied by segment with segment 11 (NSP5) exhibiting significantly higher adaptation to host genomes. Furthermore, RVA codon usage patterns appeared optimized for expression in humans and birds relative to the other hosts examined, suggesting that translational efficiency is not a barrier in RVA zoonosis.

Pathogenesis of Gram-Negative Bacteremia

2021 ◽  
Vol 34 (2) ◽  
Author(s):  
Caitlyn L. Holmes ◽  
Mark T. Anderson ◽  
Harry L. T. Mobley ◽  
Michael A. Bachman
Keyword(s):  
Immune Responses ◽  
Global Economy ◽  
Human Infection ◽  
Model Systems ◽  
Small Subset ◽  
Gram Negative ◽  
Content Type ◽  
Capsule Production ◽  
Gram Negative Bacteremia ◽  
Species Specific

SUMMARY Gram-negative bacteremia is a devastating public health threat, with high mortality in vulnerable populations and significant costs to the global economy. Concerningly, rates of both Gram-negative bacteremia and antimicrobial resistance in the causative species are increasing. Gram-negative bacteremia develops in three phases. First, bacteria invade or colonize initial sites of infection. Second, bacteria overcome host barriers, such as immune responses, and disseminate from initial body sites to the bloodstream. Third, bacteria adapt to survive in the blood and blood-filtering organs. To develop new therapies, it is critical to define species-specific and multispecies fitness factors required for bacteremia in model systems that are relevant to human infection. A small subset of species is responsible for the majority of Gram-negative bacteremia cases, including Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii. The few bacteremia fitness factors identified in these prominent Gram-negative species demonstrate shared and unique pathogenic mechanisms at each phase of bacteremia progression. Capsule production, adhesins, and metabolic flexibility are common mediators, whereas only some species utilize toxins. This review provides an overview of Gram-negative bacteremia, compares animal models for bacteremia, and discusses prevalent Gram-negative bacteremia species.

scholarly journals Genome-Wide DNA Methylation Profiles of Phlegm-Dampness Constitution

2018 ◽  
Vol 45 (5) ◽  
pp. 1999-2008 ◽  
Author(s):  
Haiqiang Yao ◽  
Shanlan Mo ◽  
Ji Wang ◽  
Yingshuai Li ◽  
Chong-Zhi Wang ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Metabolic Disorders ◽  
Mononuclear Cells ◽  
Metabolic Diseases ◽  
Body Type ◽  
Peripheral Blood Mononuclear ◽  
Molecular Features ◽  
Genome Wide ◽  
A Genome ◽  
Differentially Methylated Genes

Background/Aims: Metabolic diseases are leading health concerns in today’s global society. In traditional Chinese medicine (TCM), one body type studied is the phlegm-dampness constitution (PC), which predisposes individuals to complex metabolic disorders. Genomic studies have revealed the potential metabolic disorders and the molecular features of PC. The role of epigenetics in the regulation of PC, however, is unknown. Methods: We analyzed a genome-wide DNA methylation in 12 volunteers using Illumina Infinium Human Methylation450 BeadChip on peripheral blood mononuclear cells (PBMCs). Eight volunteers had PC and 4 had balanced constitutions. Results: Methylation data indicated a genome-scale hyper-methylation pattern in PC. We located 288 differentially methylated probes (DMPs). A total of 256 genes were mapped, and some of these were metabolic-related. SQSTM1, DLGAP2 and DAB1 indicated diabetes mellitus; HOXC4 and SMPD3, obesity; and GRWD1 and ATP10A, insulin resistance. According to Ingenuity Pathway Analysis (IPA), differentially methylated genes were abundant in multiple metabolic pathways. Conclusion: Our results suggest the potential risk for metabolic disorders in individuals with PC. We also explain the clinical characteristics of PC with DNA methylation features.

scholarly journals Identification and Characterization of a Pear Chlorotic Leaf Spot-Associated Virus, a Novel Emaravirus Associated with a Severe Disease of Pear Trees in China

Plant Disease ◽  
2020 ◽  
Vol 104 (11) ◽  
pp. 2786-2798 ◽  
Author(s):  
Huazhen Liu ◽  
Guoping Wang ◽  
Zuokun Yang ◽  
Yanxiang Wang ◽  
Zhe Zhang ◽  
...  
Keyword(s):  
Leaf Spot ◽  
High Throughput Sequencing ◽  
Southern China ◽  
Pyrus Pyrifolia ◽  
Rt Pcr ◽  
Molecular Features ◽  
A Genome ◽  
Close Phylogenetic Relationship ◽  
Chlorotic Leaf ◽  
Pear Trees

Pear chlorotic leaf spot (PCLS) is a recently emerged disease of commercially cultivated sandy pear (Pyrus pyrifolia) trees in central and southern China. By integrating high-throughput sequencing and conventional Sanger sequencing of reverse-transcription (RT)-PCR products, a novel emaravirus infecting pear trees was identified and molecularly characterized. The virus was provisionally named pear chlorotic leaf spot-associated virus (PCLSaV). PCLSaV shows the typical molecular features of members of the genus Emaravirus in the family Fimoviridae. It has a genome composed of at least five negative-sense RNA segments, with each containing a single open reading frame and two complementary 13-nucleotide stretches at the 5′ and 3′ termini. PCLSaV shows a close phylogenetic relationship with recognized emaraviruses but forms a separate clade. Moreover, double-membrane-bound bodies were observed in PCLSaV-infected tissues and in extracts of PCLSaV-infected leaves. For the first time, our study revealed the profile distribution of viral RNA reads from the RNA-seq libraries of three samples along the RNA1 to RNA5 of an emaravirus. Field surveys combined with specific RT-PCR assays revealed the presence of PCLSaV in almost all PCLS-diseased pear samples, strongly supporting the association of the virus with the PCLS disease. This study revealed the first emaravirus infecting pear trees and its association with a severe pear chlorotic leaf disease.

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