A Pvs25 mRNA vaccine induces complete and durable transmission-blocking immunity to Plasmodium vivax.

Plasmodium vivax (P. vivax) is the major malaria parasite outside of Africa and no vaccine is available against it. A vaccine that interrupts parasite transmission (transmission-blocking vaccine, TBV) is considered highly desirable to reduce the spread of P. vivax and to accelerate its elimination. However, the development of a TBV against this pathogen has been hampered by the inability to culture the parasite as well as the low immunogenicity of the vaccines developed to date. Pvs25 is the most advanced TBV antigen candidate for P. vivax. However, in previous phase I clinical trials, TBV vaccines based on Pvs25 yielded low antibody responses or had unacceptable safety profiles. As the nucleoside-modified mRNA-lipid nanoparticle (mRNA-LNP) vaccine platform proved to be safe and effective in humans, we generated and tested mRNA-LNP vaccines encoding several versions of Pvs25 in mice. We found that in a prime-boost vaccination schedule, all Pvs25 mRNA-LNP vaccines elicited robust antigen-specific antibody responses. Furthermore, when compared with a Pvs25 recombinant protein vaccine formulated with Montanide ISA-51 adjuvant, the full-length Pvs25 mRNA-LNP vaccine induced a stronger and longer-lasting functional immunity. Seven months after the second vaccination, vaccine-induced antibodies retained the ability to fully block P. vivax transmission in direct membrane feeding assays, whereas the blocking activity induced by the protein/ISA-51 vaccine dropped significantly. Taken together, we report on mRNA vaccines targeting P. vivax and demonstrate that Pvs25 mRNA-LNP outperformed an adjuvanted Pvs25 protein vaccine suggesting that it is a promising candidate for further testing in non-human primates.

Development of an ectopic huLiver model for Plasmodium liver stage infection.

Early Plasmodium falciparum and P. vivax infection requires parasite replication within host hepatocytes, referred to as liver stage (LS). However, limited understanding of infection dynamics in human LS exists due to species-specificity challenges. Reported here is a reproducible, easy-to-manipulate, and moderate-cost in vivo model to study human Plasmodium LS in mice; the ectopic huLiver model. Ectopic huLiver tumors were generated through subcutaneous injection of the HC-04 cell line and shown to be infectible by both freshly dissected sporozoites and through the bite of infected mosquitoes. Evidence for complete LS development was supported by the transition to blood-stage infection in mice engrafted with human erythrocytes. Additionally, this model was successfully evaluated for its utility in testing antimalarial therapeutics, as supported by primaquine acting as a causal prophylactic against P. falciparum. Presented here is a new platform for the study of human Plasmodium infection with the potential to aid in drug discovery.

Plasmodium vivax latent liver infection is characterized by persistent hypnozoites, hypnozoite-derived schizonts, and time-dependent efficacy of primaquine.

Plasmodium vivax is a malaria-causing pathogen that establishes a dormant form in the liver (the hypnozoite), which can activate weeks, months, or years after the primary infection to cause a relapse, characterized by secondary blood-stage infection. These asymptomatic and undetectable latent liver infections present a significant obstacle to the goal of global malaria eradication. We use a human liver-chimeric mouse model (FRG huHep) to study P. vivax hypnozoite latency and activation in an in vivo model system. Functional activation of hypnozoites and formation of secondary schizonts is demonstrated by first eliminating primary liver schizonts using a schizont-specific antimalarial tool compound, and then measuring recurrence of secondary liver schizonts in the tissue and an increase in parasite RNA within the liver. We also reveal that, while primaquine does not immediately eliminate hypnozoites from the liver, it arrests developing schizonts and prevents activation of hypnozoites, consistent with its clinical activity in humans. Our findings demonstrate that the FRG huHep model can be used to study the biology of P. vivax infection and latency and assess the activity of anti-relapse drugs.

Variation in terpenoids in leaves of Artemisia annua grown under different LED spectra resulting in diverse antimalarial activities against Plasmodium falciparum.

BACKGROUND: Productivities of bioactive compounds in high-value herbs and medicinal plants are often compromised by uncontrollable environmental parameters. Recent advances in the development of plant factories with artificial lighting (PFAL) have led to improved qualitative and/or quantitative production of bioactive compounds in several medicinal plants. However, information concerning the effect of light qualities on plant pharmaceutical properties is limited. The influence of three different light-emitting diode (LED) spectra on leaf fresh weight (FW), bioactive compound production and bioactivity of Artemisia annua L. against the malarial parasite Plasmodium falciparum NF54 was investigated. Correlation between the A. annua metabolites and antimalarial activity of light-treated plant extracts were also determined. RESULTS: Artemisia annua plants grown under white and blue spectra that intersected at 445 nm exhibited higher leaf FW and increased amounts of artemisinin and artemisinic acid, with enhanced production of several terpenoids displaying a variety of pharmacological activities. Conversely, the red spectrum led to diminished production of bioactive compounds and a distinct metabolite profile compared with other wavelengths. Crude extracts obtained from white and blue spectral treatments exhibited 2 times higher anti-Plasmodium falciparum activity than those subjected to the red treatment. Highest bioactivity was 4 times greater than those obtained from greenhouse-grown plants. Hierarchical cluster analysis (HCA) revealed a strong correlation between levels of several terpenoids and antimalarial activity, suggesting that these compounds might be involved in increasing antimalarial activity. CONCLUSIONS: Results demonstrated a strategy to overcome the limitation of A. annua cultivation in Bangkok, Thailand. A specific LED spectrum that operated in a PFAL system promoted the accumulation of some useful phytochemicals in A. annua, leading to increased antimalarial activity. Therefore, the application of PFAL with appropriate light spectra showed promise as an alternative method for industrial production of A. annua or other useful medicinal plants with minimal environmental influence.

Morphological alteration of the pancreatic islet in ovariectomized rats fed a high-fat high-fructose diet.

Diabetes and its complications are major causes of mortality worldwide. Type 2 diabetes coexists with insulin resistance and ß-cell dysfunction, which are aggravated by overconsumption and estrogen-deprived conditions. However, the morphology of pancreatic islets in a combined condition of excessive caloric intake and estrogen deficiency has never been described. Herein, we examined morphological changes in the pancreatic islets of ovariectomized (OVX) rats fed a high-fat high-fructose diet (HFFD) for 12 weeks. The histological changes in the size and number of pancreatic islets were assessed by hematoxylin-eosin and immunohistochemical staining. Enlarged pancreatic islets with fat deposition in OVX rats were accompanied by whole-body insulin resistance and hyperglycemia. The addition of a HFFD to OVX rats (OVX + HFFD) further aggravated insulin resistance, with a substantial increase in the density of enlarged pancreatic islets and fat accumulation. The augmented number of enlarged islets was correlated with elevated plasma glucose and insulin levels. Intriguingly, unlike the HFFD and OVX alone, the OVX + HFFD markedly expanded the area of insulin-producing ß-cells and glucagon-producing α-cells. Importantly, enlarged islets, pancreatic fat deposits, and diabetic states developing in OVX + HFFD conditions were resolved by estrogen replacement. Collectively, the morphological characteristics of pancreatic islets were influenced in an insulin-resistant state caused by estrogen deficiency and HFFD consumption and were distinct from each factor alone. A combination of estrogen deficiency with HFFD consumption worsened the integrity of pancreatic islets, ultimately resulting in disease progression. These findings expand our understanding of the causal relationship between pancreatic morphology and diabetes development and suggest therapeutic strategies.

Mice Immunized with the Vaccine Candidate HexaPro Spike Produce Neutralizing Antibodies against SARS-CoV-2.

Updated and revised versions of COVID-19 vaccines are vital due to genetic variations of the SARS-CoV-2 spike antigen. Furthermore, vaccines that are safe, cost-effective, and logistic-friendly are critically needed for global equity, especially for middle- to low-income countries. Recombinant protein-based subunit vaccines against SARS-CoV-2 have been reported using the receptor-binding domain (RBD) and the prefusion spike trimers (S-2P). Recently, a new version of prefusion spike trimers, named HexaPro, has been shown to possess two RBD in the "up" conformation, due to its physical property, as opposed to just one exposed RBD found in S-2P. Importantly, this HexaPro spike antigen is more stable than S-2P, raising its feasibility for global logistics and supply chain. Here, we report that the spike protein HexaPro offers a promising candidate for the SARS-CoV-2 vaccine. Mice immunized by the recombinant HexaPro adjuvanted with aluminum hydroxide using a prime-boost regimen produced high-titer neutralizing antibodies for up to 56 days after initial immunization against live SARS-CoV-2 infection. Also, the level of neutralization activity is comparable to that of convalescence sera. Our results indicate that the HexaPro subunit vaccine confers neutralization activity in sera collected from mice receiving the prime-boost regimen.

Efficacy of Eosin Dye Removal by Peanut Shell Agrowaste Adsorbent

Abstract Peanut shell (PS) which is an excessive waste-product from agricultural processes, it can be recycled to a natural adsorbent for example it uses as removal dyes. Synthetic dye effluent without improperly discharged from industries to the river cause wastewater and damage to living organisms, especially, anionic dyes are difficult removed by conventional treatments such as biological, chemical, oxidation, and physical-filtration. However, an adsorption treatment is widely used for decolorization of dyes and give the best results for removal of various types of dissolved coloring materials. This research was used Eosin Y (EO) for the anionic model of dyeing wastewater and used PS for agrowaste adsorbent. The purpose of this study was investigated the efficiency adsorption of EO removal by PS. This efficiency adsorption was measured by different PS dosages, contact times, adsorbate concentration and equilibrium data. The results can be concluded that the PS had the efficiency adsorption of EO removal due to the equilibrium adsorption capacity (qe) and the highest dose of PS were balanced to adsorption of dye. The highest EO removal percentage was found in 87.7%, the qe was 0.351 mg g-1 and can adsorb from 10 mg L-1 to 1.23 mg L-1 in 25 g L-1 of PS dose at 30 minutes. In addition, the PS structure was found in multi-layer and many porous which is suitable for adsorbent. The morphological examination of PS was shown before and after adsorption that not changed. Therefore, PS might be an alternative choice for removal dye, and be used for the recycle adsorbent agrowaste as a commercial product for adding their values.

Validation of PfSNP-LAMP-Lateral Flow Dipstick for Detection of Single Nucleotide Polymorphism Associated with Pyrimethamine Resistance in Plasmodium falciparum.

The loop-mediated isothermal amplification coupled with lateral flow dipstick (PfSNP-LAMP-LFD) was recently developed to detect single nucleotide polymorphism (AAT → ATT), corresponding to substitution of asparagine to isoleucine at amino acid position 51 in the P. falciparumdhfr-ts gene associated with antifolate resistance. In this present study, the PfSNP-LAMP-LFD was validated on 128 clinical malaria samples of broad ranged parasite densities (10 to 87,634 parasites per microliter of blood). The results showed 100% accuracy for the detection of single nucleotide polymorphism for N51I mutation. Indeed, the high prevalence of N51I in the Pfdhfr-ts gene detected in the clinical samples is in line with reports of widespread antifolate resistant P. falciparum in Thailand. The relationship between enzyme choice and reaction time was observed to have an effect on PfSNP-LAMP-LFD specificity; however, the method yielded consistent results once the conditions have been optimized. The results demonstrate that PfSNP-LAMP-LFD is a simple method with sufficient sensitivity and specificity to be deployed in routine surveillance of antifolate resistance molecular marker and inform antimalarial management policy.

A Humanized Mouse Model for Plasmodium vivax to Test Interventions that Block Liver Stage to Blood Stage Transition and Blood Stage Infection.

The human malaria parasite Plasmodium vivax remains vastly understudied, mainly due to the lack of suitable laboratory models. Here, we report a humanized mouse model to test interventions that block P. vivax parasite transition from liver stage infection to blood stage infection. Human liver-chimeric FRGN huHep mice infected with P. vivax sporozoites were infused with human reticulocytes, allowing transition of exo-erythrocytic merozoites to reticulocyte infection and development into all erythrocytic forms, including gametocytes, in vivo. In order to test the utility of this model for preclinical assessment of interventions, the invasion blocking potential of a monoclonal antibody targeting the essential interaction of the P. vivax Duffy Binding Protein with the Duffy antigen receptor was tested by passive immunization. This antibody inhibited invasion by over 95%, providing unprecedented in vivo evidence that PvDBP constitutes a promising blood stage vaccine candidate and proving our model highly suitable to test blood stage interventions.

The Plasmodium liver-specific protein 2 (LISP2) is an early marker of liver stage development.

Plasmodium vivax hypnozoites persist in the liver, cause malaria relapse and represent a major challenge to malaria elimination. Our previous transcriptomic study provided a novel molecular framework to enhance our understanding of the hypnozoite biology (Voorberg-van der Wel A, et al., 2017). In this dataset, we identified and characterized the Liver-Specific Protein 2 (LISP2) protein as an early molecular marker of liver stage development. Immunofluorescence analysis of hepatocytes infected with relapsing malaria parasites, in vitro (P. cynomolgi) and in vivo (P. vivax), reveals that LISP2 expression discriminates between dormant hypnozoites and early developing parasites. We further demonstrate that prophylactic drugs selectively kill all LISP2-positive parasites, while LISP2-negative hypnozoites are only sensitive to anti-relapse drug tafenoquine. Our results provide novel biological insights in the initiation of liver stage schizogony and an early marker suitable for the development of drug discovery assays predictive of anti-relapse activity.

Cytotoxicity and histopathological analysis of titanium nanoparticles via Artemia salina.

The consumption trend of nanoparticles by industry in this moment pays attention to titanium nanoparticles (TiNPs), due to their various applications: personal care products, household products, food industry, electronic devices, and healthcare products. Rising consumption of TiNPs without specific regulatory criteria for control safety releasing quantification leads to concern on the topic of environmental contamination and injurious effect. Therefore, this study investigates TiNP toxicities on aquatic animals representing hazardous effects to natural water resource, by determining 24-h LC50 of TiNPs with histopathology investigation. We select brine shrimp (Artemia salina) as a model. Ten adults A. salina were incubated at room temperature for 24 h with various concentrations of TiNPs in triplicate. The mortality number of A. salina was recorded and LC50 value was calculated. The LC50 result is 1693.43 mg/L. Next, A. salina histopathology investigation was done by selecting the living ones after incubation for 24 h with 25% LC50 of TiNPs. We performed tissue processing, embedding, sectioning, and H&E staining, and observed under light microscope. Histopathology reveals TiNP occlusion throughout the intestinal tract. Epithelial cells show abnormal morphology such as hyperplasia, villus deformation, disorganized arrangement, severe edema, and necrosis area. Consequently, the current study shows the severity of TiNP effects on aquatic microcrustaceans and their negative impact on the ecosystem. Furthermore, this information will aid the elucidation of TiNP toxicity effect and the risk of ecosystem disruptions.

The sbGnRH-GTH system in the female short mackerel, Rastrelliger brachysoma (Bleeker, 1851), during breeding season: implications for low gamete production in captive broodstock.

The short mackerel (Rastrelliger brachysoma) is one of the most economically important fish in Thailand; it is also a prime candidate for mariculture but unfortunately is plagued by reproductive problems that cause low production of gametes in captivity. An understanding of how the brain, pituitary, and gonad axis (BPG) from the neuroendocrine system are involved in the reproductive activity of wild and captive R. brachysoma should help clarify the situation. In this study, we investigated changes in the sea bream gonadotropin-releasing hormone (sbGnRH)-gonadotropin (GTH) system in the female short mackerel, Rastrelliger brachysoma (Bleeker, 1851), during breeding season. sbGnRH-immunoreactive (ir) cell bodies were detected in the nucleus preopticus-periventricularis including nucleus periventricularis (NPT), nucleus preopticus (Np), and nucleus lateralis tuberis (NLT). Additionally, the sbGnRH-ir fibers protruded into the proximal par distalis (PPD) where GTH (FSH and LH) cells were detected. The number of sbGnRH-ir cell bodies and GTH cells and level of LH mRNA were significantly higher in the breeding season than those in the non-breeding season. Moreover, the number of sbGnRH-ir cell bodies and GTH cells and levels of sbGnRH and GTH (FSH and LH) mRNA were significantly higher in the wild fish than those in the cultured broodstock. It is suggested that the wild fish tended to have better reproductive system than hatchery fishes. This could be related to the endocrinological dysfunction and the reproductive failure in the hatchery condition. Moreover, the changes of all of the hormonal level could potentially be applied to R. brachysoma aquaculture.

Correction to: The sbGnRH-GTH system in the female short mackerel, Rastrelliger brachysoma (Bleeker, 1851), during breeding season: implications for low gamete production in captive broodstock.

The published online version of this article contained outdated Figs. 4 and 5. The original article has been corrected.

Identification of a PH domain-containing protein which is localized to crystalloid bodies of Plasmodium ookinetes.

BACKGROUND: For the success of the malaria control and eradication programme it is essential to reduce parasite transmission by mosquito vectors. In the midguts of mosquitoes fed with parasite-infected blood, sexual-stage parasites fertilize to develop into motile ookinetes that traverse midgut epithelial cells and reside adjacent the basal lamina. Therefore, the ookinete is a promising target of transmission-blocking vaccines to break the parasite lifecycle in mosquito vectors. However, the molecular mechanisms of ookinete formation and invasion of epithelial cells have not been fully elucidated. A unique structure called the crystalloid body has been identified in the ookinete cytoplasm by electron microscopy, but its biological functions remain unclear. METHODS: A recombinant protein of a novel molecule, designated as crystalloid body specific PH domain-containing protein of Plasmodium yoelii (PyCryPH), was synthesized using a wheat germ cell-free system. Specific rabbit antibodies against PyCryPH were obtained to characterize the expression and localization of PyCryPH during sexual-stage parasite development. In addition, PyCryPH knockout parasites were generated by targeted gene disruption to examine PyCryPH function in mosquito-stage parasite development. RESULTS: Western blot and immunofluorescence assays using specific antibodies showed that PyCryPH is specifically expressed in zygotes and ookinetes. By immunoelectron microscopy it was demonstrated that PyCryPH is localized within crystalloid bodies. Parasites with a disrupted PyCryPH gene developed normally into ookinetes and formed oocysts on the basal lamina of midguts. In addition, the number of sporozoites residing in salivary glands was comparable to that of wild-type parasites. CONCLUSIONS: CryPH, containing a signal peptide and PH domain, is predominantly expressed in zygotes and ookinetes and is localized to crystalloid bodies in P. yoelii. CryPH accumulates in vesicle-like structures prior to the appearance of typical crystalloid bodies. Unlike other known crystalloid body localized proteins, CryPH does not appear to have a multiple domain architecture characteristic of the LAP/CCp family proteins. Although CryPH is highly conserved among Plasmodium, Babesia, Theileria, and Cryptosporidium, PyCryPH is dispensable for the development of invasive ookinetes and sporozoites in mosquito bodies.

The Micronemal Plasmodium Proteins P36 and P52 Act in Concert to Establish the Replication-Permissive Compartment Within Infected Hepatocytes.

Within the liver, Plasmodium sporozoites traverse cells searching for a "suitable" hepatocyte, invading these cells through a process that results in the formation of a parasitophorous vacuole (PV), within which the parasite undergoes intracellular replication as a liver stage. It was previously established that two members of the Plasmodium s48/45 protein family, P36 and P52, are essential for productive invasion of host hepatocytes by sporozoites as their simultaneous deletion results in growth-arrested parasites that lack a PV. Recent studies point toward a pathway of entry possibly involving the interaction of P36 with hepatocyte receptors EphA2, CD81, and SR-B1. However, the relationship between P36 and P52 during sporozoite invasion remains unknown. Here we show that parasites with a single P52 or P36 gene deletion each lack a PV after hepatocyte invasion, thereby pheno-copying the lack of a PV observed for the P52/P36 dual gene deletion parasite line. This indicates that both proteins are equally important in the establishment of a PV and act in the same pathway. We created a Plasmodium yoelii P36mCherry tagged parasite line that allowed us to visualize the subcellular localization of P36 and found that it partially co-localizes with P52 in the sporozoite secretory microneme organelles. Furthermore, through co-immunoprecipitation studies in vivo, we determined that P36 and P52 form a protein complex in sporozoites, indicating a concerted function for both proteins within the PV formation pathway. However, upon sporozoite stimulation, only P36 was released as a secreted protein while P52 was not. Our results support a model in which the putatively glycosylphosphatidylinositol (GPI)-anchored P52 may serve as a scaffold to facilitate the interaction of secreted P36 with the host cell during sporozoite invasion of hepatocytes.

Transcriptomic analysis reveals reduced transcriptional activity in the malaria parasite Plasmodium cynomolgi during progression into dormancy.

Relapses of Plasmodium dormant liver hypnozoites compromise malaria eradication efforts. New radical cure drugs are urgently needed, yet the vast gap in knowledge of hypnozoite biology impedes drug discovery. We previously unraveled the transcriptome of 6 to 7 day-old P. cynomolgi liver stages, highlighting pathways associated with hypnozoite dormancy (Voorberg-van der Wel et al., 2017). We now extend these findings by transcriptome profiling of 9 to 10 day-old liver stage parasites, thus revealing for the first time the maturation of the dormant stage over time. Although progression of dormancy leads to a 10-fold decrease in transcription and expression of only 840 genes, including genes associated with housekeeping functions, we show that pathways involved in quiescence, energy metabolism and maintenance of genome integrity remain the prevalent pathways active in mature hypnozoites.

Characterization of Plasmodium vivax Proteins in Plasma-Derived Exosomes From Malaria-Infected Liver-Chimeric Humanized Mice.

Exosomes are extracellular vesicles of endocytic origin containing molecular signatures implying the cell of origin; thus, they offer a unique opportunity to discover biomarkers of disease. Plasmodium vivax, responsible for more than half of all malaria cases outside Africa, is a major obstacle in the goal of malaria elimination due to the presence of dormant liver stages (hypnozoites), which after the initial infection may reactivate to cause disease. Hypnozoite infection is asymptomatic and there are currently no diagnostic tools to detect their presence. The human liver-chimeric (FRG huHep) mouse is a robust P. vivax infection model for exo-erythrocytic development of liver stages, including hypnozoites. We studied the proteome of plasma-derived exosomes isolated from P. vivax infected FRG huHep mice with the objective of identifying liver-stage expressed parasite proteins indicative of infection. Proteomic analysis of these exosomes showed the presence of 290 and 234 proteins from mouse and human origin, respectively, including canonical exosomal markers. Human proteins include proteins previously detected in liver-derived exosomes, highlighting the potential of this chimeric mouse model to study plasma exosomes derived unequivocally from human hepatocytes. Noticeably, we identified 17 parasite proteins including enzymes, surface proteins, components of the endocytic pathway and translation machinery, as well as uncharacterized proteins. Western blot analysis validated the presence of human arginase-I and an uncharacterized P. vivax protein in plasma-derived exosomes. This study represents a proof-of-principle that plasma-derived exosomes from P. vivax infected FRG-huHep mice contain human hepatocyte and P. vivax proteins with the potential to unveil biological features of liver infection and identify biomarkers of hypnozoite infection.

Controlled rapid synthesis and in vivo immunomodulatory effects of LM α(1,6)mannan with an amine linker.

The synthetic lipomannan (LM) α(1,6)mannans, already equipped with an amine linker on the reducing end, are rapidly synthesized in a size-, regio-, and stereocontrolled reaction. The size of the mannans is regulated through the concentration of the linker, applied during the controlled ring-opening polymerization reaction. The versatile amine linker enables a variety of glycan conjugations. The synthetic α(1,6)mannans exert adjuvant activities for a real vaccine antigen, tetanus toxoid (TT) in vitro, as demonstrated by the increased secretion of proinflammatory cytokines TNF-α and IL-6 from the treated macrophages. A conjugation of synthetic α(1,6)mannan with TT can also enhance immune response to TT in vivo after immunization as shown by an increase in TNF-α, IFN-γ, and IL-2 production in splenocytes.

Synthesis and Immunological Studies of the Lipomannan Backbone Glycans Found on the Surface of Mycobacterium tuberculosis.

Investigations into novel bacterial drug targets and vaccines are necessary to overcome tuberculosis. Lipomannan (LM), found on the surface of Mycobacterium tuberculosis (Mtb), is actively involved in the pathogenesis and survival of Mtb. Here, we report for the first time a rapid synthesis and biological activities of an LM glycan backbone, α(1-6)mannans. The rapid synthesis is achieved via a regio- and stereoselective ring opening polymerization to generate multiple glycosidic bonds in one simple chemical step, allowing us to finish assembling the defined polysaccharides of 5-20 units within days rather than years. Within the same pot, the polymerization is terminated by a thiol-linker to serve as a conjugation point to carrier proteins and surfaces for immunological experiments. The synthetic glycans are found to have adjuvant activities in vivo. The interactions with DC-SIGN demonstrated the significance of α(1-6)mannan motif present in LM structure. Moreover, surface plasmon resonance (SPR) showed that longer chain of synthetic α(1-6)mannans gain better lectin's binding affinity. The chemically defined components of the bacterial envelope serve as important tools to reveal the interactions of Mtb with mammalian hosts and facilitate the determination of the immunologically active molecular components.