Background: Duffy blood group polymorphisms are important in areas where Plasmodium vivax predominates, because this molecule acts as a receptor for this protozoan. In the present study, Duffy blood group genotyping in P. vivax malaria patients from four different Brazilian endemic areas is reported, exploring significant associations between blood group variants and susceptibility or resistance to malaria.

Objective: In the present study, we evaluated the contribution of six genetic polymorphisms of the Renin-Angiotensis-Aldosterone system (RAAS) and clinical risk factors in the development of essential hypertension in a Brazilian rural population in the Amazon region. Methods: Eighty-two hypertensive patients and seventy-eight normotensive individuals were evaluated. Genotyping for renin (REN G1051A), angiotensinogen (AGT) M235T, insertion/deletion of angiotensin-converting enzyme (ACE I/ D), angiotensin II type 1 receptor (AGTR1) A1166C and aldosterone synthase (CYP11B2) C344T polymorphisms were performed using polymerase chain reaction, with further restriction analysis when required. The influence of genetic polymorphisms and clinical risk factors on blood pressure variation was assessed by stepwise linear regression. Results: We report the co-occurrence of clinical risk factors and angiotensin-converting enzyme (ACE) gene polymorphism in a Brazilian rural population in the Amazon region. Our results indicate that increase of systolic blood pressure (SBP) is favored by ACE I/D-D allele and advanced age, while alcohol consumption and aging are associated with high diastolic blood pressure (DBP). Conclusion: These findings suggest that in the Santa Isabel do Rio Negro population, the residents that carry ACE-D allele or have an alcohol consumption habit present higher values of SBP and DBP, respectively, with the passing of years.

BackgroundSporotrichosis is a neglected zoonosis caused by pathogenic fungi belonging to the Sporothrix schenckii complex. In Rio de Janeiro state, this disease reached an epidemic status with over 4700 domestic felines and around 4000 humans affected since the mid-90s. The present study evaluated clinical and epidemiological aspects and also the frequency of colonization and infection by these fungi in healthy cats and among those with suspicious cutaneous lesions, inhabiting four Rio de Janeiro state distinct areas.ResultsThree hundred and seventy-one cats were included in two groups: 175 healthy cats [CRG] and 196 cats showing lesions suggesting sporotrichosis [SSG]. Mycological diagnosis allowed SSG animals to be divided in positive [104 cats; +SG] and negative [92 cats; -SG] groups. Nails, oral mucosa and lesions swabs were submitted to culture and potential colonies were subculture for micromorphologycal analysis, dimorphism and molecular tests. In the CRG, only one cat was colonized in the oral cavity [0.57%]; in the -SG group, four animals showed colonization of the nail and/or oral cavity [4.3%]; while the highest frequency of colonization [39.4%] was observed in the +SG. All molecularly typed isolates were identified as S. brasiliensis.ConclusionThe results obtained here indicate that healthy cats have a minor role in sporotrichosis transmission within the state of Rio de Janeiro. Conversely, a higher participation of diseased feline in sporotrichosis transmission was evidenced, especially by the colonization of their oral cavity. Sporothrix brasiliensis equally affects and colonizes animals from distinct Rio de Janeiro state areas. Thus, we hypothesize that sporotrichosis is a uniform endemic throughout the state, whose transmission depends mainly on the contact with cats with sporotrichosis. Since Rio de Janeiro displays a world unique epidemic model of the disease, not fully understood, data on the infected and non-infected animals can be of major importance for future strategies of sporotrichosis prevention and control. Finally, considering the importance of the current concept of “one health”, the experience here observed can be helpful for distinct epizootias and/or zoonosis.

BackgroundMerozoites of Plasmodium falciparum invade through several pathways using different RBC receptors. Field isolates appear to use a greater variability of these receptors than laboratory isolates. Brazilian field isolates were shown to mostly utilize glycophorin A-independent invasion pathways via glycophorin B (GPB) and/or other receptors. The Brazilian population exhibits extensive polymorphism in blood group antigens, however, no studies have been done to relate the prevalence of the antigens that function as receptors for P. falciparum and the ability of the parasite to invade. Our study aimed to establish whether variation in the GYPB*S/s alleles influences susceptibility to infection with P. falciparum in the admixed population of Brazil.MethodsTwo groups of Brazilian Amazonians from Porto Velho were studied: P. falciparum infected individuals (cases); and uninfected individuals who were born and/or have lived in the same endemic region for over ten years, were exposed to infection but have not had malaria over the study period (controls). The GPB Ss phenotype and GYPB*S/s alleles were determined by standard methods. Sixty two Ancestry Informative Markers were genotyped on each individual to estimate admixture and control its potential effect on the association between frequency of GYPB*S and malaria infection.Results GYPB*S is associated with host susceptibility to infection with P. falciparum; GYPB*S/GYPB*S and GYPB*S/GYPB*s were significantly more prevalent in the in the P. falciparum infected individuals than in the controls (69.87% vs. 49.75%; P<0.02). Moreover, population genetics tests applied on the GYPB exon sequencing data suggest that natural selection shaped the observed pattern of nucleotide diversity.ConclusionEpidemiological and evolutionary approaches suggest an important role for the GPB receptor in RBC invasion by P. falciparum in Brazilian Amazons. Moreover, an increased susceptibility to infection by this parasite is associated with the GPB S+ variant in this population.

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Studies of Plasmodium falciparum invasion pathways in field isolates have been limited. Red blood cell (RBC) invasion is a complex process involving two invasion protein families; Erythrocyte Binding-Like (EBL) and the Reticulocyte Binding-Like (PfRh) proteins, which are polymorphic and not fully characterized in field isolates. To determine the various P. falciparum invasion pathways used by parasite isolates from South America, we studied the invasion phenotypes in three regions: Colombia, Peru and Brazil. Additionally, polymorphisms in three members of the EBL (EBA-181, EBA-175 and EBL-1) and five members of the PfRh (PfRh1, PfRh2a, PfRh2b, PfRh4, PfRh5) families were determined. We found that most P. falciparum field isolates from Colombia and Peru invade RBCs through an atypical invasion pathway phenotypically characterized as resistant to all enzyme treatments (NrTrCr). Moreover, the invasion pathways and the ligand polymorphisms differed substantially among the Colombian and Brazilian isolates while the Peruvian isolates represent an amalgam of those present in the Colombian and Brazilian field isolates. The NrTrCr invasion profile was associated with the presence of the PfRh2a pepC variant, the PfRh5 variant 1 and EBA-181 RVNKN variant. The ebl and Pfrh expression levels in a field isolate displaying the NrTrCr profile also pointed to PfRh2a, PfRh5 and EBA-181 as being possibly the major players in this invasion pathway. Notably, our studies demonstrate the uniqueness of the Peruvian P. falciparum field isolates in terms of their invasion profiles and ligand polymorphisms, and present a unique opportunity for studying the ability of P. falciparum parasites to expand their invasion repertoire after being reintroduced to human populations. The present study is directly relevant to asexual blood stage vaccine design focused on invasion pathway proteins, suggesting that regional invasion variants and global geographical variation are likely to preclude a simple one size fits all type of vaccine.

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