Amino Acid Sequence Similarity Research Articles

Functions of MdTINY, a member of the apple dehydration responsive element binding-A4

The dehydration responsive element binding (DREB) transcription factors play an important role in plant growth and development and are extensively involved in plant responses to abiotic stress. The DREB family contains six subfamilies, and TINY belongs to the DREB-A4 subfamily. The Arabidopsis thaliana TINY gene, AtTINY, plays a role in regulating plant growth and responses to stress. In order to investigate the evolutionary characterization of the DREB-A4 subfamily and the biological function of the MdTINY gene in apple (Malus domestica), in this study, we used the databases GDDH13 and TAIR and online tools (Expasy and WoLF PSORT) to study the biological information of the DREB-A4 subfamily in apple. In addition, the tertiary structures of the proteins were predicted. The apple DREB-A4 subfamily contained 22 genes, all of which had a conserved AP2 domain, and subcellular localization predictions showed that DREB-A4 subfamily proteins were mainly located in the nucleus. The transgenic calli of MdTINY were obtained by the Agrobacterium-mediated transformation method, and the main biological functions of MdTINY were explored by quantitative real-time PCR (qRT-PCR) combined with anthocyanin content determination. MdTINY shared the highest amino acid sequence similarity with AtTINY. The coding region of MdTINY had a full length of 759 bp, encoding 252 amino acid residues. Analysis of the promoter elements and expression patterns indicated that MdTINY was responsive to light and multiple stress conditions. MdTINY was localized in the nucleus and had transcriptional autoactivation activity. The overexpression of MdTINY in calli inhibited normal growth and promoted anthocyanoside accumulation. These results indicated that MdTINY negatively regulated apple plant growth and promoted fruit coloring, providing a candidate gene for the breeding of apple varieties with high quality of fruit color.

Conserved pattern-based classification of human odorant receptor multigene family

Conserved protein-coding sequences are critical for maintaining protein function across species. Odorant receptors (ORs), a large poorly understood multigene family responsible for odor detection, lack comprehensive classification methods that reflect their functional diversity. In this study, we propose a new approach called conserved motif-based classification (CMC) for classifying ORs based on amino acid sequence similarities within conserved motifs. Specifically, we focused on three well-conserved motifs: MAYDRYVAIC in TM3, KAFSTCASH in TM6, and PMLNPFIY in TM7. Using an unsupervised clustering technique, we classified human ORs (hORs) into two main clusters with six sub-clusters. CMC partly reflects previously identified subfamilies, revealing altered residue positions among the sub-clusters. These altered positions interacted with specific residues within or adjacent to the transmembrane domain, suggesting functional implications. Furthermore, we found that the CMC correlated with both ligand responses and ectopic expression patterns, highlighting its relevance to OR function. This conserved motif-based classification will help in understanding the functions and features that are not understood by classification based solely on entire amino acid sequence similarity.

Identification of receptor-binding protein and host receptor of non-lytic dsRNA phage phiNY.

To date, complete genome sequences of 14 double-stranded RNA (dsRNA) phages are available, and studies have shown that the host range of dsRNA phages is limited. The hosts of most dsRNA phages belong to the genus Pseudomonas. However, the dsRNA phage phiNY, which has a non-lytic life cycle, was isolated from Microvirgula aerodenitrificans. Currently, the interaction between dsRNA phage phiNY and its host bacteria is unclear, which is not beneficial to a comprehensive understanding of dsRNA phage biology and the exploitation of dsRNA phage with non-lytic life cycle for biomedical applications and others. Phage adsorption is a crucial step through the interactions between receptor-binding protein (RBP) of the phage and its receptors to initiate the infection process, which dictates host range specificity. Thus, we identified the RBP and host receptor of phiNY. Through homology alignment, amino acid sequence similarity analysis, and the phylogenetic tree analysis, orf11, located in the M-segment of dsRNA phage phiNY, encodes a putative RBP. We further performed the whole-cell enzyme-linked immunosorbent assay (ELISA), western blotting assay, and indirect immunofluorescence assay and demonstrated that this orf11 is an RBP. Finally, using affinity chromatography, ELISA, and dynamic light scattering, we identified lipopolysaccharides (LPSs) on the surface of the host M. aerodenitrificans strain LH9 as host receptors involved in the adsorption of the dsRNA bacteriophage phiNY and observed the state of phiNY RBP after combining with LPS by atomic force microscopy. These results will guide future studies on phage-host interaction in a dsRNA phage with a non-lytic life cycle.IMPORTANCEThe interactions between the lytic dsRNA phages and their host receptors have been clarified in previous studies. However, the interaction between the dsRNA phage phiNY (which has a non-lytic life cycle) and its host receptors during the dsRNA phage adsorption process was unknown. Here, we found that phiNY uses the orf11 protein as a receptor-binding protein (RBP). In addition, we found that this orf11 recognizes lipopolysaccharide from the host bacterium Microvirgula aerodenitrificans strain LH9 as a specific receptor. These results suggest that phiNY, like lytic dsRNA phages, uses an RBP to bind to a similar host receptor (i.e., lipopolysaccharide). Determining the interaction between the dsRNA phage phiNY and its host receptors will help to elucidate the mechanisms underlying the phiNY non-lytic life cycle and enhance our understanding of its infection mechanism.

Transcription factor networks drive perforin activity in the anti-bacterial immune response of tilapia

Perforin, produced by natural killer (NK) cells and cytotoxic T lymphocytes (CTLs), is one of the effectors of cell-mediated cytotoxicity (CMC) in vertebrates, playing a paramount role in killing target cells. However, whether and how perforin is involved in adaptive immune responses in early vertebrates remains unclear. Using Nile tilapia (Oreochromis niloticus) as a model, we investigated the characteristics of perforin in early vertebrates. Oreochromis niloticus perforin (OnPRF) possesses 2 conserved functional domains, membrane attack complex/perforin (MACPF) and protein kinase C conserved region 2 (C2) domains, although they share low amino acid sequence similarity with other homologs. OnPRF was widely expressed in various immune tissues and could respond to lymphocyte activation and T-cell activation in vitro at both the transcriptional and protein levels, indicating that it may be involved in adaptive immune responses. Furthermore, after infection with Edwardsiella piscicida and Aeromonas hydrophila, the mRNA and protein levels of OnPRF were significantly up-regulated within the adaptive immune response period. Additionally, we revealed that many transcription factors were involved in the transcriptional regulation of OnPRF, including p65, c-Fos, c-Jun, STAT1 and STAT4, and there was a synergy among these transcription factors. Overall, these findings demonstrate the involvement of OnPRF in T-cell activation and adaptive immune response in tilapia, thus providing new evidence for comprehending the evolution of immune response in early vertebrates.

Two homologous genes encoding interleukin (IL)-34 in the common carp (Cyprinus carpio L.): Roles in inflammatory modulation and anti-bacterial defense

In mammals, interleukin 34 (IL-34) is a ligand for macrophage colony-stimulating factor receptor (M-CSFR), promoting inflammatory responses and inducing the synthesis and secretion of various cytokines. However, studies on its function in lower vertebrates is limited, and its evolutionary relationship with homologous molecules in mammals remains unclear. In this study, two IL-34-encoding genes were cloned and identified in common carp (Cyprinus carpio L.), designated as CcIL-34A and CcIL-34B, with an amino acid sequence similarity of 77.7 %. Gene synteny analysis revealed that the IL-34 gene loci are relatively conserved, and both are located downstream of SF3B3. The expression patterns of CcIL-34s were analyzed using qRT-PCR, and this showed that they are expressed across all tested tissues, with higher levels in the liver, spleen, and head kidney and lower levels in the gills and intestines. Following infection with Aeromonas hydrophila, the mRNA expression levels of CcIL-34s in the gills, head kidney, intestines, and spleen were significantly upregulated. Immunofluorescence was also employed to assess changes in CcIL-34 protein expression, showing a significant increase in carp spleens 24 h after A. hydrophila infection, suggesting that CcIL-34s contribute to host defense against this bacterium. To investigate the immunological function of IL-34 in vivo, pc-CcIL-34A and pc-CcIL-34B eukaryotic expression plasmids were constructed and injected intramuscularly into fish. Five days after injection, the expression levels of inflammation-related cytokines in the head kidney and spleen were significantly altered. Furthermore, 24 h post-A. hydrophila infection, the bacterial loads in the liver, spleen, and kidneys were significantly reduced. Ten days post-infection, the survival rates in the groups with CcIL-34A and CcIL-34B overexpression were 40 % and 36.7 %, respectively, compared to 16.7 % in the control group. These findings suggest that CcIL-34s are involved in modulating inflammatory responses, enhancing the immune response, and improving survival rates in fish following bacterial infection, thus supporting the potential use of IL-34 molecules in aquaculture.

Expression of laccase and ascorbate oxidase affects lignin composition in Arabidopsis thaliana stems.

Lignin is a phenolic polymer that is a major source of biomass. Oxidative enzymes, such as laccase and peroxidase, are required for lignin polymerisation. Laccase is a member of the multicopper oxidase family and has a high amino acid sequence similarity with ascorbate oxidase. However, the process of functional differentiation between the two enzymes remains poorly understood. In this study, the common ancestry sequence of laccase and ascorbate oxidase (AncMCO) was predicted via phylogenetic reconstruction, and its in vivo effect on lignin biosynthesis in Arabidopsis thaliana was assessed. The estimated AncMCO sequence conserved key residues that coordinate with copper ions, implying that the electron transfer system is likely to be conserved in AncMCO. However, multiple insertions/deletions corresponding to protein surface structures have been found between laccase, ascorbate oxidase, and AncMCO. The overexpression of canonical laccase (AtLAC4) and ascorbate oxidase (AtAAO1) in A. thaliana resulted in notable increases of syringyl/guaiacyl lignin unit ratio in stems, whereas, in contrast, the overexpression of AncMCO did not show any detectable change in lignin deposition. Transcriptomic analysis revealed that the AtAAO1-overexpressing line exhibited significant changes in the expression of a wide range of cell wall biosynthesis genes. These results highlight the importance of the molecular evolution of multicopper oxidase, which drives lignin biosynthesis during plant evolution.

Cloning and Expression of Pigeon-Derived Escherichia coli Type 1 Pilus Clusters and Analysis of Amino Acid Sequence Characteristics of Functional Proteins.

Type 1 pili, as an important virulence factor of E. coli, has certain homology between APEC and UPEC, but the homology degree is not clear enough. This study aims to compare the homology between them. The recombinant bacteria were constructed by homologous recombination. The pili were observed by TEM, and the hemagglutination characteristics were determined by MHSA. The complete gene sequence was determined by sequencing, and the amino acid sequences of the functional proteins of type 1 pili of APEC and UPEC were compared. TEM showed that they could express pili, which were slender, straight, and dense. Stable-pUC-fimBH has MHSA but stable-pUC-fimBG does not. The amino acid sequence similarity of FimB of NJ05 and UPEC was 98.8%, FimE was 99.4%, and the similarity between them was 51.5%. Compared with UPEC's type 1 pili FimC and FimD sequences, the similarity was 99.52% and 87.8%, respectively. The amino acid sequence of FimA of NJ05 was 89-96%, similar to UPEC, and the N-terminal and C-terminal amino acid sequences were exactly the same. The gene sequence and amino acid sequence similarity of FimH between them were both above 99%. The similarity of the pilus binding domain of FimH was 52.8%, but only 27.6% in the receptor binding domain. A few of the same amino acid residues were found in the corresponding regions of FimA, FimF, FimG, and FimH. The type 1 pili of APEC and UPEC come from the same origin, which is helpful to further reveal the pathogenic mechanism of E. coli infection in the poultry respiratory tract.

Complete genome sequence of lima bean endornavirus 1: a putative new member of the genus Alphaendornavirus (family Endornaviridae).

In this study, we completely sequenced the genome of a new member of the genus Alphaendornavirus, family Endornaviridae, from lima bean (Phaseolus lunatus), for which we propose the name "lima bean endornavirus 1" (LbEV1). The complete genome of LbEV1 consists of 15,265 nucleotides, including a stretch of 12 cytosine residues at its 3' end, and contains a long single open reading frame (ORF) coding for a 4980-aa-long polyprotein. Analysis of the polyprotein sequence revealed the presence of four conserved functional domains (in order from the N- to C-terminus): viral helicase 1, peptidase _C97, glycosyltransferase_GTB-type, and viral RNA-dependent RNA polymerase (RdRP). The LbEV1 polyprotein showed the highest amino acid sequence similarity (63% identity and 98% coverage) to Phaseolus vulgaris endornavirus 3 (PvEV3) and also showed 42% identity (95% coverage) to Geranium carolinianum endornavirus. Phylogenetic analysis based on the viral RdRp domain showed that LbEV1 belongs to a subclade within the genus Alphaendornavirus that includes three other viruses infecting plants of the genus Phaseolus.

Subclass IId bacteriocins targeting mannose phosphotransferase system-Structural diversity and implications for receptor interaction and antimicrobial activity.

The bacterial mannose phosphotransferase system (Man-PTS) mediates uptake of selected monosaccharides. Simultaneously, it is a receptor for diverse bacteriocins such as subclass IIa pediocin-like bacteriocins and some subclass IId ones (garvicins ABCQ, lactococcins ABZ, BacSJ, ubericin K, and angicin). So far, no attempt has been made to categorize this ever-expanding group of bacteriocins. Here, we identified Man-PTS as a receptor for a number of previously uncharacterized bacteriocins, and demonstrated that they all belong to a large family of Man-PTS-binding nonpediocin-like peptides, providing new insights into their structure and function. Based on amino acid sequence similarities between members of this family, we propose their classification into five groups. This classification conveniently distinguishes bacteriocins with specific structures and properties regarding their spectrum of antimicrobial activity and pattern of interaction with Man-PTS. With respect to the latter, we indicate individual amino acid residues or regions of Man-PTS and the bacteriocin responsible for their interaction. In Man-PTS, these residues localize to the exterior of the transport complex, specifically the extracellular loop of the so-called Vmotif domain-containing regions γ and/or γ+, and to the interior of the transport complex, specifically the interface between the Core and Vmotif domains. Finally, we propose that while the bacteriocins from separate groups display specific binding patterns to Man-PTS, the general mechanism of their interaction with the receptor is universal despite significant differences in their predicted structures, i.e. after initial docking on the bacterial cell through an interaction with the Man-PTS regions γ and/or γ+, they pull away its Core and Vmotif from one another to form a pore across the membrane.

Combination of oncolytic Maraba virus with immune checkpoint blockade overcomes therapy resistance in an immunologically cold model of advanced melanoma with dysfunctional T-cell receptor signalling

BackgroundOver the past decade, cancer immunotherapies have revolutionized the treatment of melanoma; however, responses vary across patient populations. Recently, baseline tumor size has been identified as an independent prognostic factor...

Identification and Functional Analysis of V-ATPaseA and C Genes in Hyphantria cunea.

Vacuolar (H+)-ATPases (V-ATPases) are ATP-driven proton pumps that play multifaceted roles across various organisms. Despite their widespread significance, the functional implications of V-ATPase genes in Hyphantria cunea, an invasive forest pest with a global presence, have yet to be elucidated. In this study, two specific V-ATPase genes from H. cunea were identified and analyzed, namely HcV-ATPase A (accession number: OR217451) and HcV-ATPase C (accession number: OR217452). Phylogenetic analysis and multiple sequence alignment reveal that HcV-ATPase A shares the highest amino acid sequence similarity with SfV-ATPase A, while HcV-ATPase C is most similar to HaV-ATPase C. Spatiotemporal expression profiles, determined via RT-qPCR, demonstrate that both HcV-ATPase A and HcV-ATPase C are expressed throughout all larval developmental stages, with HcV-ATPase A predominantly expressed in the midgut and HcV-ATPase C showing high expression in the epidermis. RNA interference (RNAi) targeting of these genes significantly suppressed their expression by 62.7% and 71.0% 120 h post-injection, leading to halted larval growth and increased mortality rates of 61.7% and 46.7%, respectively. Further investigations using immunohistochemistry, hematoxylin and eosin (HE) staining, and transmission electron microscopy (TEM) revealed that gene silencing induced vesiculation and subsequent losses or sloughing of intestinal parietal cells, alongside an increase in the number of autophagic cells. Additionally, the silencing of HcV-ATPase A and C genes resulted in a reduced gut epidermal cell layer thickness and further increases in goblet cell numbers. Importantly, RNAi of HcV-ATPase A and C did not affect the expression levels of one another, suggesting independent functional pathways. This study provides foundational insights into the role of V-ATPase in H. cunea and identifies potential targets for the biocontrol of its larvae, contributing to the understanding of V-ATPase mechanisms and their application in pest management strategies.

Identification of a novel waikavirus infecting Pittosporum tobira in China.

A novel waikavirus, tentatively named "Pittosporum tobira waikavirus" (PtWV), was identified in Pittosporum tobira plants exhibiting mosaic and ringspot symptoms on foliage in Yunnan, China. The full-length genomic sequence was determined by high-throughput sequencing and rapid amplification of cDNA ends. The genome of PtWV is 12,709 nt in length and has a large open reading frame (ORF) of 11,010 nt, encoding a polyprotein, and a small ORF that encodes a 13.2-kDa bellflower vein chlorosis virus (BVCV)-like protein. Phylogenetic analysis and sequence alignment revealed that PtWV is closely related to actinidia yellowing virus 1 (AcYV1), which shares the highest amino acid (aa) sequence similarity (50.1% identity) in the Pro-RdRp region. To the best of our knowledge, this is the first report of a novel waikavirus in P. tobira.

Molecular characterization of birch toti-like virus, a plant-associated member of the new family Orthototiviridae.

A novel totivirus, named "birch toti-like virus" (BTLV), was discovered in European white birch (Betula pendula) plants. The genome of BTLV is 4,967 nucleotides long and contains two overlapping open reading frames (ORFs) coding for the capsid protein (CP) and an RNA-dependent RNA-polymerase (RdRP). The encoded CP and RdRP proteins shared 46.9% and 60.2% amino acid sequence identity, respectively, with those of Panax notoginseng virus B. The presence of a putative slippery heptamer signal 82 nt upstream of the stop codon of ORF1 suggests that a -1 translational frameshifting strategy is involved in the expression of ORF2, like in other totiviruses. Phylogenetic analysis based on the CP and RdRP amino acid sequences placed this virus within a clade of plant-associated totiviruses, with taro-associated virus as its closest relative. Hence, based on its distinct host and the amino acid sequence similarity between BTLV and its relatives, we conclude that birch toti-like virus is a new member of the genus Totivirus.

Identification and characterization of the COPII vesicle-forming GTPase Sar1 in Chlamydomonas.

Eukaryotic cells are highly compartmentalized, requiring elaborate transport mechanisms to facilitate the movement of proteins between membrane-bound compartments. Most proteins synthesized in the endoplasmic reticulum (ER) are transported to the Golgi apparatus through COPII-mediated vesicular trafficking. Sar1, a small GTPase that facilitates the formation of COPII vesicles, plays a critical role in the early steps of this protein secretory pathway. Sar1 was characterized in yeast, animals and plants, but no Sar1 homolog has been identified and functionally analyzed in algae. Here we identified a putative Sar1 homolog (CrSar1) in the model green alga Chlamydomonas reinhardtii through amino acid sequence similarity. We employed site-directed mutagenesis to generate a dominant-negative mutant of CrSar1 (CrSar1DN). Using protein secretion assays, we demonstrate the inhibitory effect of CrSar1DN on protein secretion. However, different from previously studied organisms, ectopic expression of CrSar1DN did not result in collapse of the ER-Golgi interface in Chlamydomonas. Nonetheless, our data suggest a largely conserved role of CrSar1 in the ER-to-Golgi protein secretory pathway in green algae.

Hitting Epstein Barr virus where it hurts: computational methods exploration for siRNA therapy in alleviating Epstein Barr virus-induced multiple sclerosis.

Multiple sclerosis (MS), an intricate neurological disorder, continues to challenge our understanding of the pivotal interplay between the immune system and the central nervous system (CNS). This condition arises from the immune system's misdirected attack on nerve fiber protection, known as myelin sheath, alongside nerve fibers themselves. This enigmatic condition, characterized by demyelination and varied clinical manifestations, prompts exploration into its multifaceted etiology and potential therapeutic avenues. Research has revealed a potential connection between Epstein Barr virus (EBV), specifically Epstein Barr Nuclear Antigen 1 (EBNA-1), and MS. The immune response to EBNA-1 antigen triggers the production of anti-EBNA-1 molecules, including IgG that identify a similar amino acid sequence to EBNA-1 in myelin, inadvertently targeting myelin sheath and contributing to MS progression. Currently, no treatment exists for EBNA-1-induced MS apart from symptom management. Addressing this, a novel potential therapeutic avenue utilizing small interference RNAs (siRNA) has been designed. By targeting the conserved EBNA-1 gene sequences in EBV types 1 and 2, five potential siRNAs were identified in our analysis. Thorough evaluations encompassing off-target binding, thermodynamics and secondary structure elucidation, efficacy prediction, siRNA-mRNA sequence binding affinity exploration, melting temperature, and docking of siRNAs with human argonaute protein 2 (AGO2) were conducted to elucidate the siRNAs efficiency. These designed siRNA molecules harnessed promising silencing activity in the EBNA-1 gene encoding the EBNA-1 antigen protein and thus have the potential to mitigate the severity of this dangerous virus.

Genome-Wide Transcriptional Roles of KSHV Viral Interferon Regulatory Factors in Oral Epithelial Cells.

The viral interferon regulatory factors (vIRFs) of KSHV are known to dysregulate cell signaling pathways to promote viral oncogenesis and to block antiviral immune responses to facilitate infection. However, it remains unknown to what extent each vIRF plays a role in gene regulation. To address this, we performed a comparative analysis of the protein structures and gene regulation of the four vIRFs. Our structure prediction analysis revealed that despite their low amino acid sequence similarity, vIRFs exhibit high structural homology in both their DNA-binding domain (DBD) and IRF association domain. However, despite this shared structural homology, we demonstrate that each vIRF regulates a distinct set of KSHV gene promoters and human genes in epithelial cells. We also found that the DBD of vIRF1 is essential in regulating the expression of its target genes. We propose that the structurally similar vIRFs evolved to possess specialized transcriptional functions to regulate specific genes.

Genome-wide identification and examination of the wheat glycosyltransferase family 43 regulation during Fusarium graminearum infection

In Arabidopsis and rice, the glycosyltransferase (GT) 43 family is involved in xylan synthesis. However, there have been limited reports on the study of the TaGT43 family in wheat. In this study, 28 TaGT43 family members were identified in wheat (Triticum aestivum L.) and clustered into three major groups based on the similarity of amino acid sequences. The results of the TaGT43 family's conserved motif and gene structure analyses agree with this result. Collinearity analysis revealed segmental duplications mainly promoted TaGT43 family expansion. cis-Acting element analysis revealed that the TaGT43 genes were involved in the light response, phytohormone response, abiotic/biotic stress response, and growth and development. The TaGT43 family showed a tissue-specific expression pattern, primarily expressed in roots and stems. Besides, the transcriptional and expression levels of multiple TaGT43 genes were upregulated during the infection of F. graminearum. According to metabolomics studies, F. graminearum infection affected the phenylpropanoid biosynthesis pathway in wheat, a critical factor in cell wall construction. Furthermore, GO enrichment analysis indicated that the TaGT43 genes play a significant role in cell wall organization. Based on these results, it may be concluded that the TaGT43 family mediates cell wall organization in response to F. graminearum infection.

The clade-specific target recognition mechanisms of plant RISCs.

Eukaryotic Argonaut proteins (AGOs) assemble RNA-induced silencing complexes (RISCs) with guide RNAs that allow binding to complementary RNA sequences and subsequent silencing of target genes. The model plant Arabidopsis thaliana encodes 10 different AGOs, categorized into three distinct clades based on amino acid sequence similarity. While clade 1 and 2 RISCs are known for their roles in post-transcriptional gene silencing, and clade 3 RISCs are associated with transcriptional gene silencing in the nucleus, the specific mechanisms of how RISCs from each clade recognize their targets remain unclear. In this study, I conducted quantitative binding analyses between RISCs and target nucleic acids with mismatches at various positions, unveiling distinct target binding characteristics unique to each clade. Clade 1 and 2 RISCs require base pairing not only in the seed region but also in the 3' supplementary region for stable target RNA binding, with clade 1 exhibiting a higher stringency. Conversely, clade 3 RISCs tolerate dinucleotide mismatches beyond the seed region. Strikingly, they bind to DNA targets with an affinity equal to or surpassing that of RNA, like prokaryotic AGO complexes. These insights challenge existing views on plant RNA silencing and open avenues for exploring new functions of eukaryotic AGOs.

Differential protective impact of peptide vaccine formulae targeting the lung- and liver-stage of challenge Schistosoma mansoni infection in mice

The study aimed to elicit protective immune responses against murine schistosomiasis mansoni at the parasite lung- and liver stage. Two peptides showing amino acid sequence similarity to gut cysteine peptidases, which induce strong memory immune effectors in the liver, were combined with a peptide based on S. mansoni thioredoxin peroxidase (TPX), a prominent lung-stage schistosomula excretory-secretory product, and alum as adjuvant. Only one of the 2 cysteine peptidases-based peptides in a multiple antigenic peptide construct (MAP-3 and MAP-4) appeared to adjuvant protective immune responses induced by the TPX peptide in a MAP form. Production of TPX MAP-specific IgG1 serum antibodies, and increase in lung interleukin-1 (IL-1), uric acid, and reactive oxygen species (ROS) content were associated with significant (P < 0.05) 50 % reduction in recovery of lung-stage larvae. Increase in lung triglycerides and cholesterol levels appeared to provide the surviving worms with nutrients necessary for a stout double lipid bilayer barrier at the parasite-host interface. Surviving worms-released products elicited memory responses to the MAP-3 immunogen, including production of specific IgG1 antibodies and increase in liver IL-33 and ROS. Reduction in challenge worm burden recorded 45 days post infection did not exceed 48 % associated with no differences in parasite egg counts in the host liver and small intestine compared to unimmunized adjuvant control mice. Alum adjuvant assisted the second peptide, MAP-4, in production of IgG1, IgG2a, IgG2b and IgA specific antibodies and increase in liver ROS, but with no protective potential, raising doubt about the necessity of adjuvant addition. Accordingly, different vaccine formulas containing TPX MAP and 1, 2 or 3 cysteine peptidases-derived peptides with or without alum were used to immunize parallel groups of mice. Compared to unimmunized control mice, significant (P < 0.05 to < 0.005) 22 to 54 % reduction in worm burden was recorded in the different groups associated with insignificant changes in parasite egg output. The results together indicated that a schistosomiasis vaccine able to entirely prevent disease and halt its transmission still remains elusive.

Functional Divergence of the Paralog Salmonella Effector Proteins SopD and SopD2 and Their Contributions to Infection.

Salmonella enterica is a leading cause of bacterial food-borne illness in humans and is responsible for millions of cases annually. A critical strategy for the survival of this pathogen is the translocation of bacterial virulence factors termed effectors into host cells, which primarily function via protein-protein interactions with host proteins. The Salmonella genome encodes several paralogous effectors believed to have arisen from duplication events throughout the course of evolution. These paralogs can share structural similarities and enzymatic activities but have also demonstrated divergence in host cell targets or interaction partners and contributions to the intracellular lifecycle of Salmonella. The paralog effectors SopD and SopD2 share 63% amino acid sequence similarity and extensive structural homology yet have demonstrated divergence in secretion kinetics, intracellular localization, host targets, and roles in infection. SopD and SopD2 target host Rab GTPases, which represent critical regulators of intracellular trafficking that mediate diverse cellular functions. While SopD and SopD2 both manipulate Rab function, these paralogs display differences in Rab specificity, and the effectors have also evolved multiple mechanisms of action for GTPase manipulation. Here, we highlight this intriguing pair of paralog effectors in the context of host-pathogen interactions and discuss how this research has presented valuable insights into effector evolution.