Changes in the Cervical Microbiota of Women with Different High-Risk Human Papillomavirus Loads.

The cervical microbiota is essential in female sexual health, and its altered states seem to have a central role in the dynamic of high-risk papillomavirus (hrHPV) infections. This study aimed to evaluate the variation in bacterial communities' compositions according to hrHPV. We collected two samples per woman, with a difference of 12 ± 1 months between them, and performed a follow-up on 66 of these women. The viral load (VL) of the hrHPV was estimated by quantitative PCR (qPCR), then it was normalized (using the HMBS gene as reference) and transformed to the Log10 scale to facilitate the interpretation. The VL was categorized as Negative, without hrHPV copies; Low, less than 100 hrHPV copies; Medium, between 100 to 102 hrHPV copies; and High, >102 hrHPV copies. The microbiota composition was described through the Illumina Novaseq PE250 platform. The diversity analyses revealed changes regarding the hrHPV VL, where women with low VL (<100 hrHPV copies) presented high diversity. The community state type (CST) IV was the most common. However, in women with high VL, a lower association with Lactobacillus depletion was found. Lactobacillus gallinarum and L. iners were the most abundant species in women with high VL, whereas women with low VL had a 6.06 greater probability of exhibiting Lactobacillus dominance. We identified conspicuous differences in the abundance of 78 bacterial genera between women with low and high VL, where 26 were depleted (e.g., Gardnerella) and 52 increased (e.g., Mycoplasma). A multilevel mixed-effects linear regression showed changes in the diversity due to the interaction between the measurement time and the VL, with a decrease in diversity in the second follow-up in women with low VL (Coeff. = 0.47), whereas the women with medium VL displayed an increase in diversity (Coeff. = 0.58). Here, we report for the first time that the cervical microbiota is influenced by the number of copies of hrHPV, where a decrease in the abundance of Lactobacillus, greater diversity, and enrichment of bacterial taxa is relevant in women with low VL.

The Cellular and Molecular Interaction Between Erythrocytes and Plasmodium falciparum Merozoites.

Plasmodium falciparum is the most lethal human malaria parasite, partly due to its genetic variability and ability to use multiple invasion routes via its binding to host cell surface receptors. The parasite extensively modifies infected red blood cell architecture to promote its survival which leads to increased cell membrane rigidity, adhesiveness and permeability. Merozoites are initially released from infected hepatocytes and efficiently enter red blood cells in a well-orchestrated process that involves specific interactions between parasite ligands and erythrocyte receptors; symptoms of the disease occur during the life-cycle's blood stage due to capillary blockage and massive erythrocyte lysis. Several studies have focused on elucidating molecular merozoite/erythrocyte interactions and host cell modifications; however, further in-depth analysis is required for understanding the parasite's biology and thus provide the fundamental tools for developing prophylactic or therapeutic alternatives to mitigate or eliminate Plasmodium falciparum-related malaria. This review focuses on the cellular and molecular events during Plasmodium falciparum merozoite invasion of red blood cells and the alterations that occur in an erythrocyte once it has become infected.

Cervical cancer screening programme attendance and compliance predictors regarding Colombia's Amazon region.

BACKGROUND: Cervical cancer (CC) promotion and prevention (P&P) programmes' challenge lies in guaranteeing that follow-up strategies have a real impact on reducing CC-related mortality rates. CC P&P programme compliance and coverage rates are relevant indicators for evaluating their success and good performance; however, such indicators' frequency rates are considerably lower among women living in rural and border areas. This study was aimed at identifying factors associated with CC screening programme attendance for women living in Colombia's Amazon region. METHODS: This study (qualitative and quantitative phases) was carried out between September 2015 and November 2016; women residing in the border towns of Leticia and Puerto Nariño participated in it. The first phase (qualitative) involved interviews and focus group discussions; this led to establishing factors related to CC P&P programme attendance which were used in the quantitative phase for designing a survey for determining the strength of association in a logistic regression model. The terms attendance and compliance were considered to apply to women who had followed the 1-1-3 scheme throughout their lives, i.e. a cytology examination every 3 years after receiving two consecutive negative annual cytology results. RESULTS: Inclusion criteria were met by 309 women (≥18-year-olds having an active sexual life, having resided in the target community for at least one year); 15.2% had suitable P&P programme follow-up. Screening programme attendance was positively associated with first intercourse after becoming 20 years-old (aOR: 3.87; 1.03-9.50 95%CI; p = 0.045), frequent contraceptive use (aOR: 3.11; 1.16-8.33 95%CI; p = 0.023), awareness of the age to participate in P&P programmes (aOR: 2.69; 1.08-6.68 95%CI; p = 0.032), awareness of cytology's usefulness in identifying cervical abnormalities (aOR: 2.43; 1.02-5.77 95%CI; p = 0.043) and considering cytology important (aOR: 2.64; 1.12-6.19 95%CI; p = 0.025). Women living in rural areas had a lower probability (aOR 0.43: 0.24-0.79 95%CI; p = 0.006) of adhering to CC P&P programmes. CONCLUSIONS: This study's findings suggested the need for including novel strategies in screening programmes which will promote CC P&P activities going beyond hospital outpatient attendance to reach the most remote or widely scattered communities, having the same guarantees regarding access, opportunity and quality. Including education-related activities and stimulating the population's awareness regarding knowledge about CC prevention could be one of the main tools for furthering the impact of attendance at and compliance with P&P programmes.

Trichomonas vaginalis follow-up and persistence in Colombian women.

Trichomonas vaginalis (TV), the most common non-viral sexually-transmitted infection is considered a neglected infection and its epidemiology is not well known. This study determined TV-infection dynamics in a retrospective cohort of Colombian women and evaluated associations between risk factors and TV-outcome. TV was identified by PCR. Cox proportional risk models were used for evaluating the relationship between TV-outcome (infection, clearance and persistence) and risk factors (sexually-transmitted infections and sociodemographic characteristics). Two hundred and sixty-four women were included in the study; 26.1% had TV at the start of the study, 40.9% suffered at least one episode of infection and 13.0% suffered more than one episode of TV during the study. Women suffering HPV had a greater risk of TV-infection (aHR 1.59), high viral-load (> 102) for HPV-16 being related to a greater risk of persistent parasite infection; a high viral load (> 102) for HPV-18 and -33 was related to a lower probability of TV-clearance. Ethnicity (afrodescendent/indigenous people: aHR 5.11) and having had more than two sexual partners (aHR 1.94) were related to greater risk of infection, contrasting with women having a background of abortions and lower probability of having TV (aHR 0.50). Women aged 35- to 49-years-old (aHR 2.08), increased years of sexual activity (aHR 1.10), multiple sexual partners (aHR 8.86) and multiparous women (aHR 3.85) led to a greater probability of persistence. Women whose cervical findings worsened had a 9.99 greater probability of TV-persistence. TV distribution was high in the study population; its coexistence with HPV and other risk factors influenced parasite infection dynamics. The results suggested that routine TV detection should be considered regarding populations at risk of infection.

Molecular characterisation of parvorder Platyrrhini IgG sub-classes.

Non-human primates (NHP) are essential in modern biomedical research; New World monkeys (NWM) are mainly used as an experimental model regarding human malaria as they provide useful information about the parasite's biology and an induced immune response. It is known that a vaccine candidate's efficacy is mediated by a protection-inducing antibody response (IgG). Not enough information is available concerning IgG subclasses' molecular characteristics regarding NHP from parvorder Platyrrhini. Understanding the nature of the humoral immune response and characterising the IgG subclasses' profile will provide valuable information about the immunomodulator mechanisms of vaccines evaluated using an NHP animal model. This article has characterised IgG subclasses in NWM (i.e. genera Aotus, Cebus, Ateles and Alouatta) based on the amplification, cloning and sequencing of the immunoglobulin heavy constant gamma (IGHG) gene's CH1 to CH3 regions. The resulting sequences enabled elucidating IGHG gene organisation; two IgG variants were found in the Aotus and Ateles monkey group and three IgG variants in the Cebus and Alouatta group. The sequences were highly conserved in Platyrrhini and had a similar structure to that reported for monkeys from parvorder Catarrhini. Such information will help in developing tools for a detailed characterisation of the humoral immune response in an NWM experimental animal model.

A novel platform for peptide-mediated affinity capture and LC-MS/MS identification of host receptors involved in Plasmodium invasion.

Successful Plasmodium falciparum invasion of red blood cells includes the orderly execution of highly specific receptor-ligand molecular interactions between the parasite's proteins and the red blood cell membrane proteins. There is a growing need for elucidating receptor-ligand pairings, which will help in understanding the parasite's biology and provide the fundamental basis for developing prophylactic or therapeutic alternatives leading to mitigating or eliminating this type of malaria. We have thus used Plasmodium falciparum RH5 - derived peptides and ghost red blood cell proteins in synthetic peptide affinity capture assays to identify important host receptors used by Plasmodium spp. in the invasion of red blood cells. LC-MS/MS analysis confirmed the extensively described interaction between PfRH5 and the basigin receptor on the red blood cell membrane. As shown here, tagged synthetic peptides displaying high binding ability to erythrocytes can be used to identify receptors present in protein extracts from ghost red blood cells via affinity capture and LC-MS/MS. SIGNIFICANCE: The article describes a novel approach for identifying red blood cell receptors based on the ability of synthetic peptides having high red blood cell binding capacity to capture Plasmodium spp. receptors on proteins extracted from ghost red blood cells. Specifically, novel methods to identify Plasmodium falciparum reticulocyte binding protein homolog 5 PfRH5 and basigin interaction using a combination of affinity capture and LC-MS/MS assays is described. Identification of these host RBC receptors interacting with malarial parasite proteins is of utmost importance in studying the disease's pathogenesis and will provide crucial information in understanding the parasite's biology. In addition, data from these studies can be used to identify potential therapeutic target(s) to mitigate or eliminate this debilitating disease.

A Comprehensive Review of the Immunological Response against Foot-and-Mouth Disease Virus Infection and Its Evasion Mechanisms.

Foot-and-mouth disease (FMD) is a highly contagious viral disease, which has been reported for over 100 years, and against which the struggle has lasted for the same amount of time. It affects individuals from the order Artiodactyla, such as cattle, swine, sheep, wild animals from this order, and a few non-cloven hoofed species, such as mice and elephants. FMD causes large-scale economic losses for agricultural production systems; morbidity is almost 100% in an affected population, accompanied by a high mortality rate in young animals due to myocarditis or an inability to suckle if a mother is ill. The aetiological agent is an Aphthovirus from the family Picornaviridae, having seven serotypes: A, O, C, SAT1, SAT2, SAT3, and Asia 1. Serotype variability means that an immune response is serospecific and vaccines are thus designed to protect against each serotype independently. A host's adaptive immune response is key in defence against pathogens; however, this virus uses successful strategies (along with most microorganisms) enabling it to evade a host's immune system to rapidly and efficiently establish itself within such host, and thus remain there. This review has been aimed at an in-depth analysis of the immune response in cattle and swine regarding FMD virus, the possible evasion mechanisms used by the virus and describing some immunological differences regarding these species. Such aspects can provide pertinent knowledge for developing new FMD control and prevention strategies.

Hotspots in Plasmodium and RBC Receptor-Ligand Interactions: Key Pieces for Inhibiting Malarial Parasite Invasion.

Protein-protein interactions (IPP) play an essential role in practically all biological processes, including those related to microorganism invasion of their host cells. It has been found that a broad repertoire of receptor-ligand interactions takes place in the binding interphase with host cells in malaria, these being vital interactions for successful parasite invasion. Several trials have been conducted for elucidating the molecular interface of interactions between some Plasmodium falciparum and Plasmodium vivax antigens with receptors on erythrocytes and/or reticulocytes. Structural information concerning these complexes is available; however, deeper analysis is required for correlating structural, functional (binding, invasion, and inhibition), and polymorphism data for elucidating new interaction hotspots to which malaria control methods can be directed. This review describes and discusses recent structural and functional details regarding three relevant interactions during erythrocyte invasion: Duffy-binding protein 1 (DBP1)-Duffy antigen receptor for chemokines (DARC); reticulocyte-binding protein homolog 5 (PfRh5)-basigin, and erythrocyte binding antigen 175 (EBA175)-glycophorin A (GPA).

Shorter Antibacterial Peptide Having High Selectivity for E. coli Membranes and Low Potential for Inducing Resistance.

Antimicrobial peptides (AMPs) have been recognised as a significant therapeutic option for mitigating resistant microbial infections. It has been found recently that Plasmodium falciparum-derived, 20 residue long, peptide 35409 had antibacterial and haemolytic activity, making it an AMP having reduced selectivity, and suggesting that it should be studied more extensively for obtaining new AMPs having activity solely targeting the bacterial membrane. Peptide 35409 was thus used as template for producing short synthetic peptides (<20 residues long) and evaluating their biological activity and relevant physicochemical characteristics for therapeutic use. Four of the sixteen short peptides evaluated here had activity against E. coli without any associated haemolytic effects. The 35409-1 derivative (17 residues long) had the best therapeutic characteristics as it had high selectivity for bacterial cells, stability in the presence of human sera, activity against E. coli multiresistant clinical isolates and was shorter than the original sequence. It had a powerful membranolytic effect and low potential for inducing resistance in bacteria. This peptide's characteristics highlighted its potential as an alternative for combating infection caused by E. coli multiresistant bacteria and/or for designing new AMPs.

Plasmodium falciparum pre-erythrocytic stage vaccine development.

Worldwide strategies between 2010 and 2017 aimed at controlling malarial parasites (mainly Plasmodium falciparum) led to a reduction of just 18% regarding disease incidence rates. Many biologically-derived anti-malarial vaccine candidates have been developed to date; this has involved using many experimental animals, an immense amount of work and the investment of millions of dollars. This review provides an overview of the current state and the main results of clinical trials for sporozoite-targeting vaccines (i.e. the parasite stage infecting the liver) carried out by research groups in areas having variable malaria transmission rates. However, none has led to promising results regarding the effective control of the disease, thereby making it necessary to complement such efforts at finding/introducing new vaccine candidates by adopting a multi-epitope, multi-stage approach, based on minimal subunits of the main sporozoite proteins involved in the invasion of the liver.

Plasmodium falciparum Blood Stage Antimalarial Vaccines: An Analysis of Ongoing Clinical Trials and New Perspectives Related to Synthetic Vaccines.

Plasmodium falciparum malaria is a disease causing high morbidity and mortality rates worldwide, mainly in sub-Saharan Africa. Candidates have been identified for vaccines targeting the parasite's blood stage; this stage is important in the development of symptoms and clinical complications. However, no vaccine that can directly affect morbidity and mortality rates is currently available. This review analyzes the formulation, methodological design, and results of active clinical trials for merozoite-stage vaccines, regarding their safety profile, immunological response (phase Ia/Ib), and protective efficacy levels (phase II). Most vaccine candidates are in phase I trials and have had an acceptable safety profile. GMZ2 has made the greatest progress in clinical trials; its efficacy has been 14% in children aged less than 5 years in a phase IIb trial. Most of the available candidates that have shown strong immunogenicity and that have been tested for their protective efficacy have provided good results when challenged with a homologous parasite strain; however, their efficacy has dropped when they have been exposed to a heterologous strain. In view of these vaccines' unpromising results, an alternative approach for selecting new candidates is needed; such line of work should be focused on how to increase an immune response induced against the highly conserved (i.e., common to all strains), functionally relevant, protein regions that the parasite uses to invade target cells. Despite binding regions tending to be conserved, they are usually poorly antigenic and/or immunogenic, being frequently discarded as vaccine candidates when the conventional immunological approach is followed. The Fundación Instituto de Inmunología de Colombia (FIDIC) has developed a logical and rational methodology based on including conserved high-activity binding peptides (cHABPs) from the main P. falciparum biologically functional proteins involved in red blood cell (RBC) invasion. Once appropriately modified (mHABPs), these minimal, subunit-based, chemically synthesized peptides can be used in a system covering the human immune system's main genetic variables (the human leukocyte antigen HLA-DR isotype) inducing a suitable, immunogenic, and protective immune response in most of the world's populations.

Specific Binding Peptides from Rv3632: A Strategy for Blocking Mycobacterium tuberculosis Entry to Target Cells?

Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis (Mtb, i.e., the aetiological agent); the WHO has established this disease as high priority due to its ensuing mortality. Mtb uses a range of mechanisms for preventing its elimination by an infected host; new, viable alternatives for blocking the host-pathogen interaction are thus sought constantly. This article updates our laboratory's systematic search for antigens using bioinformatics tools to clarify the Mtb H37Rv Rv3632 protein's topology and location. This article reports a C-terminal region consisting of peptides 39255 and 39256 (81Thr-Arg114) having high specific binding regarding two infection-related cell lines (A549 and U937); they inhibited mycobacterial entry to U937 cells in a concentration-dependent manner. Rv3632 forms part of the mycobacterial cell envelope, formed by six linear synthetic peptides. Circular dichroism enabled determining the protein's secondary structure. It was also found that peptide 39254 (61Gly-Thr83) was a HABP for alveolar epithelial cells and inhibited mycobacteria entry to these cells regardless of concentration. Sera from active or latent tuberculosis patients did not recognise HABPs 39254 and 39256. These sequences represent a promising approach aiming at their ongoing modification and for including them when designing a multi-epitope, anti-tuberculosis vaccine.

Behavior and abundance of Anopheles darlingi in communities living in the Colombian Amazon riverside.

In the past few years, relative frequencies of malaria parasite species in communities living in the Colombian Amazon riverside have changed, being Plasmodium vivax (61.4%) and Plasmodium malariae (43.8%) the most frequent. Given this epidemiological scenario, it is important to determine the species of anophelines involved in these parasites' transmission. This study was carried out in June 2016 in two indigenous communities living close to the tributaries of the Amazon River using protected human bait. The results of this study showed a total abundance of 1,085 mosquitos, of which 99.2% corresponded to Anopheles darlingi. Additionally, only two anopheline species were found, showing low diversity in the study areas. Molecular confirmation of some individuals was then followed by evolutionary analysis by using the COI gene. Nested PCR was used for identifying the three Plasmodium species circulating in the study areas. Of the two species collected in this study, 21.0% of the An. darlingi mosquitoes were infected with P. malariae, 21.9% with P. vivax and 10.3% with Plasmodium falciparum. It exhibited exophilic and exophagic behavior in both study areas, having marked differences regarding its abundance in each community (Tipisca first sampling 49.4%, Tipisca second sampling 39.6% and Doce de Octubre 10.9%). Interestingly, An. mattogrossensis infected by P. vivax was found for the first time in Colombia (in 50% of the four females collected). Analysis of An. darlingi COI gene diversity indicated a single population maintaining a high gene flow between the study areas. The An. darlingi behavior pattern found in both communities represents a risk factor for the region's inhabitants living/working near these sites. This highlights the need for vector control efforts such as the use of personal repellents and insecticides for use on cattle, which must be made available in order to reduce this Anopheline's abundance.

Synthetic Evaluation of Standard and Microwave-Assisted Solid Phase Peptide Synthesis of a Long Chimeric Peptide Derived from Four Plasmodium falciparum Proteins.

An 82-residue-long chimeric peptide was synthesised by solid phase peptide synthesis (SPPS), following the Fmoc protocol. Microwave (MW) radiation-assisted synthesis was compared to standard synthesis using low loading (0.20 mmol/g) of polyethylene glycol (PEG) resin. Similar synthetic difficulties were found when the chimeric peptide was obtained via these two reaction conditions, indicating that such difficulties were inherent to the sequence and could not be resolved using MW; by contrast, the number of coupling cycles and total reaction time became reduced whilst crude yield and percentage recovery after purification were higher for MW radiation-assisted synthesis.

Association of HIV status with infection by multiple HPV types.

OBJECTIVES: To identify the clinical and demographic characteristics of HIV-positive and HIV-negative women infected by multiple HPV types. METHODS: 1399 women participated in the study (240 HIV-positive and 1159 HIV-negative women). Samples were provided for Pap tests and for HPV detection and typing by PCR. Data were collected on HPV infection, frequency of multiple infection, and HPV type distribution. Odds ratios were reported from logistic regression models. RESULTS: Compared with HIV-negative women, HIV-positive women had higher frequencies of cervical abnormality (30% vs. 20.8%), higher HPV prevalence (68.3% vs. 51.3%) and were more commonly infected with multiple HPV types (78.7% vs. 44.3%). HPV-16 was the most common type detected in the study population, with other types showing variable associations with HIV status. Positive associations were observed between infection by multiple HPV types and HIV status, cervical abnormality and having had more than three pregnancies. The odds of multiple infection by HPV types were higher in HIV-positive women who used an intrauterine device, who had a history of abortions and who had HIV viral loads >100 000 copies/ml, whilst the odds were lower in women with >500 CD4 cells/mm3 . CONCLUSIONS: HIV immunosuppression favours infection by multiple high-risk HPV types, mainly in women affected by low-grade squamous intraepithelial lesions. Antiretroviral therapy had no effect on infection by multiple HPV types. Risk factors related to progressive damage to the cervix were positively associated with infection by multiple HPV types in women living with HIV.

Towards designing a synthetic antituberculosis vaccine: The Rv3587c peptide inhibits mycobacterial entry to host cells.

Mycobacterium tuberculosis is considered one of the most successful pathogens in the history of mankind, having caused 1.7 million deaths in 2016. The amount of resistant and extensively resistant strains has increased; BCG has been the only vaccine to be produced in more than 100 years though it is still unable to prevent the disease's most disseminated form in adults; pulmonary tuberculosis. The search is thus still on-going for candidate antigens for an antituberculosis vaccine. This paper reports the use of a logical and rational methodology for finding such antigens, this time as peptides derived from the Rv3587c membrane protein. Bioinformatics tools were used for predicting mycobacterial surface location and Rv3587c protein structure whilst circular dichroism was used for determining its peptides' secondary structure. Receptor-ligand assays identified 4 high activity binding peptides (HABPs) binding specifically to A549 alveolar epithelial cells and U937 monocyte-derived macrophages, covering the region between amino acids 116 and 193. Their capability for inhibiting Mtb H37Rv invasion was evaluated. The recognition of antibodies from individuals suffering active and latent tuberculosis and from healthy individuals was observed in HABPs capable of avoiding mycobacterial entry to host cells. The results showed that 8 HABPs inhibited such invasion, two of them being common for both cell lines: 39265 (155VLAAYVYSLDNKRLWSNLDT173) and 39266 (174APSNETLVKTFSPGEQVTTY192). Peptide 39265 was the least recognised by antibodies from the individuals' sera evaluated in each group. According to the model proposed by FIDIC regarding synthetic vaccine development, peptide 39265 has become a candidate antigen for an antituberculosis vaccine.

Mycobacterium tuberculosis H37Rv LpqG Protein Peptides Can Inhibit Mycobacterial Entry through Specific Interactions.

Mycobacterium tuberculosis is the causative agent of tuberculosis, a disease causing major mortality worldwide. As part of a systematic methodology for studying M. tuberculosis surface proteins which might be involved in host-pathogen interactions, our group found that LpqG surface protein (Rv3623) found in M. tuberculosis complex strains was located on the mycobacterial envelope and that peptide 16661 (21SGCDSHNSGSLGADPRQVTVY40) had high specific binding to U937 monocyte-derived macrophages and inhibited mycobacterial entry to such cells in a concentration-dependent way. A region having high specific binding to A549 alveolar epithelial cells was found which had low mycobacterial entry inhibition. As suggested in previous studies, relevant sequences in the host-pathogen interaction do not induce an immune response and peptides characterised as HABPs are poorly recognised by sera from individuals regardless of whether they have been in contact with M. tuberculosis. Our approach to designing a synthetic, multi-epitope anti-tuberculosis vaccine has been based on identifying sequences involved in different proteins' mycobacteria-target cell interaction and modifying their sequence to improve their immunogenic characteristics, meaning that peptide 16661 sequence should be considered in such design.

Simultaneous detection of Plasmodium vivax dhfr, dhps, mdr1 and crt-o resistance-associated mutations in the Colombian Amazonian region.

BACKGROUND: Malaria continues being a public health problem worldwide. Plasmodium vivax is the species causing the largest number of cases of malaria in Asia and South America. Due to the lack of a completely effective anti-malarial vaccine, controlling this disease has been based on transmission vector management, rapid diagnosis and suitable treatment. However, parasite resistance to anti-malarial drugs has become a major yet-to-be-overcome challenge. This study was thus aimed at determining pvmdr1, pvdhfr, pvdhps and pvcrt-o gene mutations and haplotypes from field samples obtained from an endemic area in the Colombian Amazonian region. METHODS: Fifty samples of parasite DNA infected by a single P. vivax strain from symptomatic patients from the Amazonas department in Colombia were analysed by PCR and the pvdhfr, pvdhps, pvmdr1 and pvcrt-o genes were sequenced. Diversity estimators were calculated from the sequences and the haplotypes circulating in the Colombian Amazonian region were obtained. CONCLUSION: pvdhfr, pvdhps, pvmdr1 and pvcrt-o genes in the Colombian Amazonian region are characterized by low genetic diversity. Some resistance-associated mutations were found circulating in this population. New variants are also being reported. A selective sweep signal was located in pvdhfr and pvmdr1 genes, suggesting that these mutations (or some of them) could be providing an adaptive advantage.

A Large Size Chimeric Highly Immunogenic Peptide Presents Multistage Plasmodium Antigens as a Vaccine Candidate System against Malaria.

Rational strategies for obtaining malaria vaccine candidates should include not only a proper selection of target antigens for antibody stimulation, but also a versatile molecular design based on ordering the right pieces from the complex pathogen molecular puzzle towards more active and functional immunogens. Classical Plasmodium falciparum antigens regarded as vaccine candidates have been selected as model targets in this study. Among all possibilities we have chosen epitopes of PfCSP, STARP; MSA1 and Pf155/RESA from pre- and erythrocyte stages respectively for designing a large 82-residue chimeric immunogen. A number of options aimed at diminishing steric hindrance for synthetic procedures were assessed based on standard Fmoc chemistry such as building block orthogonal ligation; pseudo-proline and microwave-assisted procedures, therefore the large-chimeric target was produced, characterized and immunologically tested. Antigenicity and functional in vivo efficacy tests of the large-chimera formulations administered alone or as antigen mixtures have proven the stimulation of high antibody titers, showing strong correlation with protection and parasite clearance of vaccinated BALB/c mice after being lethally challenged with both P. berghei-ANKA and P. yoelii 17XL malaria strains. Besides, 3D structure features shown by the large-chimera encouraged as to propose using these rational designed large synthetic molecules as reliable vaccine candidate-presenting systems.

Structural analysis of owl monkey MHC-DR shows that fully-protective malaria vaccine components can be readily used in humans.

More than 50 years ago the owl monkey (genus Aotus) was found to be highly susceptible to developing human malaria, making it an excellent experimental model for this disease. Microbes and parasites' (especially malaria) tremendous genetic variability became resolved during our malaria vaccine development, involving conserved peptides having high host cell binding activity (cHABPs); however, cHABPs are immunologically silent and must be specially modified (mHABPs) to induce a perfect fit into major histocompatibility complex (MHC) molecules (HLA in humans). Since malarial immunity is mainly antibody-mediated and controlled by the HLA-DRB genetic region, ∼1000 Aotus have been molecularly characterised for MHC-DRB, revealing striking similarity between human and Aotus MHC-DRB repertories. Such convergence suggested that a large group of immune protection-inducing protein structures (IMPIPS), highly immunogenic and protection inducers against malarial intravenous challenge in Aotus, could easily be used in humans for inducing full protection against malaria. We highlight the value of a logical and rational methodology for developing a vaccine in an appropriate animal model: Aotus monkeys.