RESUMEN Los sistemas de biodetección son poderosas herramientas biotecnológicas que se aplican ampliamente en entornos médicos y ambientales. En este artículo, proporcionamos una descripción general de un sistema de biodetección óptica desarrollado recientemente, basado en las capacidades de extinción del óxido de grafeno y las biosondas fluorescentes. Se ha demostrado que esta plataforma de biodetección es una tecnología nanofotónica rápida, rentable y fiable. En particular, se ha aprovechado para detectar analitos relevantes en matrices reales, incluidos los anticuerpos contra E. coli y COVID-19 específicos de la próstata. Además, esta tecnología permitió la detección de sialidasa en muestras clínicas, para determinar la vaginosis bacteriana. Por último, este sistema de biodetección se ha utilizado recientemente para determinar información relevante sobre la cinética de las proteínas involucradas en el proceso de biorreconocimiento, todo realizado en tiempo real y en un solo paso.

ABSTRACT Biosensing systems are powerful biotechnological tools which are widely applied in medical and environmental settings. Herein, we provide an overview of a recently developed optical biosensing system based on the quenching abilities of graphene oxide and fluorescent bioprobes. This biosensing platform has been demonstrated to be a fast, cost-effective and reliable nanophotonic technology. In particular, it has been exploited to detect relevant analytes in real matrixes, including prostate specific E. coli and COVID-19 antibodies. Besides, this technology enabled the detection of sialidase in clinical samples to determine bacterial vaginosis. This biosensing system has recently been used to determine relevant information on the kinetics of proteins involved in the biorecognition process, everything performed in real-time and in a single step.

RESUMO CONTEXTO E OBJETIVO: A vaginose bacteriana é uma condição, comum em gestantes, que aumenta a susceptibilidade a infecções sexualmente transmissíveis (IST). Considerando que adolescentes são desproporcionalmente afetadas por IST, o objetivo deste estudo foi avaliar os níveis cervicovaginais de interleucina (IL)-1 beta, IL-6, IL-8 e sialidases bacterianas em gestantes adolescentes com vaginose bacteriana. DESENHO DO ESTUDO E LOCAL: Estudo transversal em Unidade de Referência Materno Infantil (UREMIA), Belém, Pará, Brasil. MÉTODOS: Amostras vaginais das 168 gestantes adolescentes incluídas foram testadas para tricomoníase e candidíase e a microbiota vaginal foi classificada em normal, intermediária e vaginose bacteriana, segundo os critérios de Nugent (1991). Infecções cervicais por Chlamydia trachomatis eNeisseria gonorrhoeae também foram avaliadas. Os níveis de citocinas e sialidades foram quantificados, respectivamente, por método imunoenzimático e pela conversão do MUAN nos lavados cervicovaginais. Foram excluídas 48 (28,6%) adolescentes positivas para alguma das infecções investigadas. As 120 gestantes remanescentes foram agrupadas de acordo com o padrão de flora vaginal em: normal (n = 68) e vaginose bacteriana (n = 52). Níveis de citocinas e sialidases foram comparados pelo teste de Mann-Whitney, P < 0,05. RESULTADOS: As gestantes adolescentes com vaginose bacteriana entre os grupos apresentaram níveis aumentados de IL-1 beta, IL-6 and IL-8 (P < 0,05). Sialidases foram exclusivamente detectadas em 35 (67,2%) adolescentes com vaginose bacteriana. CONCLUSÕES: Não apenas a IL-1 beta e as sialidases estão aumentadas em gestantes adolescentes com vaginose bacteriana, mas também IL-6 e IL-8, indicando resposta inflamatória mais pronunciada dessa alteração de microbiota nesta população, potencializando a vulnerabilidade à aquisição de IST.

ABSTRACT CONTEXT AND OBJECTIVE: Bacterial vaginosis occurs frequently in pregnancy and increases susceptibility to sexually transmitted infections (STI). Considering that adolescents are disproportionally affected by STI, the aim of this study was to evaluate the cervicovaginal levels of interleukin (IL)-1 beta, IL-6, IL-8 and bacterial sialidase in pregnant adolescents with bacterial vaginosis. DESIGN AND SETTING: Cross-sectional study at mother and child referral units in Belém, Pará, Brazil. METHODS: Vaginal samples from 168 pregnant adolescents enrolled were tested for trichomoniasis and candidiasis. Their vaginal microbiota was classified according to the Nugent criteria (1991) as normal, intermediate or bacterial vaginosis. Cervical infection due to Chlamydia trachomatisand Neisseria gonorrhoeae was also assessed. Cytokine and sialidase levels were measured, respectively, using enzyme-linked immunosorbent assays and MUAN conversion in cervicovaginal lavages. Forty-eight adolescents (28.6%) were excluded because they tested positive for some of the infections investigated. The remaining 120 adolescents were grouped according to vaginal flora type: normal (n = 68) or bacterial vaginosis (n = 52). Their cytokine and sialidase levels were compared between the groups using the Mann-Whitney test (P < 0.05). RESULTS: The pregnant adolescents with bacterial vaginosis had higher levels of IL-1 beta, IL-6 and IL-8 (P < 0.05). Sialidase was solely detected in 35 adolescents (67.2%) with bacterial vaginosis. CONCLUSIONS: Not only IL-1 beta and sialidase levels, but also IL-6 and IL-8 levels are higher in pregnant adolescents with bacterial vaginosis, thus indicating that this condition elicits a more pronounced inflammatory response in this population, which potentially increases vulnerability to STI acquisition.

Bacterial vaginosis (VB) is a syndrome characterized by overgrowth of endogenous Gram negative bacterial flora and the lack of the normal flora. Within bacterial enzymes, sialidases have been considered a virulence factor of many pathogenic microorganisms colonizing the different mucous membranes. Their presence in vaginal discharges can be correlated with VB. The aim of this study was to detect the activity of this enzyme in women with this syndrome and without clinical evidence of genital infection. Out of a total 112 women studied, 51 were patients with VB and the other 61 women presented normal vaginal flora. For the quantification of enzyme activity, the technique based on the enzymatic hydrolysis of a derivative acid of the acetyl metoxifenil muramic acid was used. In the studied population both groups shared values from 0.5 to 5.1 nmoles of metoxifenol, whereas only 11 out of 52 patients with VB (21.17%), registered more than 5.1 nmoles. The presence of sialidase activity is not enough to confirm VB, except for values greater than 5.5 nmoles of the metoxifenol produced in the enzymatic reaction.

La vaginosis bacteriana (VB) es un síndrome caracterizado por el sobrecrecimiento bacteriano de flora endógena Gram negativa, que desplaza a la flora lactobacilar normal. Dentro de las enzimas bacterianas, las sialidasas han sido consideradas factores de virulencia de muchos microorganismos patógenos que colonizan las distintas mucosas. Su presencia en fluidos vaginales puede estar correlacionada con VB. El propósito de este estudio fue comprobar la actividad de dicha enzima en mujeres con este síndrome y sin evidencia clínica de infección genital. Se estudiaron 112 mujeres (51 fueron pacientes con VB y 61 mujeres con flora colonizante habitual). Para la cuantificación de la actividad sialidasa se empleó la técnica basada en la hidrólisis enzimática de un derivado ácido del ácido metoxifenil acetil murámico. En la población estudiada se encontró que ambos grupos mostraron valores comprendidos entre 0.5 a 5.1 nmoles de metoxifenol, mientras que 11 de 52 pacientes con VB (21.17%), registraron valores superiores a 5.1 nmoles. La presencia de actividad sialidasa solamente no es índice de VB, excepto para valores mayores de 5.5 nmoles de metoxifenol, producidos en la reacción enzimática.

The neuraminidase gene, nanH, is present in the O1, non-toxigenic Vibrio cholerae Amazonia strain. Its location has been assigned to a 150 kb NotI DNA fragment, with the use of pulsed-field gel electrophoresis and DNA hybridization. This NotI fragment is positioned inside 630 kb SfiI and 1900 kb I-CeuI fragments of chromosome 1. Association of the pathogenicity island VPI-2, carrying nanH and other genes, with toxigenic strains has been described by other authors. The presence of nanH in a non-toxigenic strain is an exception to this rule. The Amazonia strain nanH was sequenced (Genbank accession No. AY825932) and compared to available V. cholerae sequences. The sequence is different from those of pandemic strains, with 72 nucleotide substitutions. This is the first description of an O1 strain with a different nanH allele. The most variable domain of the Amazonia NanH is the second lectin wing, comprising 13 out of 17 amino acid substitutions. Based on the presence of nanH in the same region of the genome, and similarity of the adjacent sequences to VPI-2 sequences, it is proposed that the pathogenicity island VPI-2 is present in this strain.

A total of 33 crude and cloned Trypanosoma rangeli stocks found as natural infections in human from Panama and other endemic areas of Central and South America were evaluated as producers of sialidase (SA) activity through the MU-NANA fluorescence test. Negative results were observed in 6 of the isolates: Panama (4), Honduras (1), and Brazil (1). In addition, an immunoblotting analysis confirm the presence of the SA antigen in these stocks without enzymatic activity. These findings must be considered in the interpretation of the biological significance of T. rangeli SA and in the proper characterization and identification of this parasite.

Striking similarities at the morphological, molecular and biological levels exist between many trypanosomatids isolated from sylvatic insects and/or vertebrate reservoir hosts that make the identification of medically important parasites demanding. Some molecular data have pointed to the relationship between some Leishmania species and Endotrypanum, which has an important epidemiological significance and can be helpful to understand the evolution of those parasites. In this study, we have demonstrated a close genetic relationship between Endotrypanum and two new leishmanial species, L. (V.) colombiensis and L. (V.) equatorensis. We have used (a) numerical zymotaxonomy and (b) the variability of the internal transcribed spacers of the rRNA genes to examine relationships in this group. The evolutionary trees obtained revealed high genetic similarity between L. (V.) colombiensis, L. (V.) equatorensis and Endotrypanum, forming a tight cluster of parasites. Based on further results of (c) minicircle kDNA heterogeneity analysis and (d) measurement of the sialidase activity these parasites were also grouped together.

In the present investigation we studied the fusogenic process developed by influenza A, B and C viruses on cell surfaces and different factors associated with virus and cell membrane structures. The biological activity of purified virus strains was evaluated in hemagglutination, sialidase and fusion assays. Hemolysis by influenza A, B and C viruses ranging from 77.4 to 97.2%, from 20.0 to 65.0%, from 0.2 to 93.7% and from 9.0 to 76.1% was observed when human, chicken, rabbit and monkey erythrocytes, respectively, were tested at pH 5.5. At this pH, low hemolysis indexes for influenza A, B and C viruses were observed if horse erythrocytes were used as target cells for the fusion process, which could be explained by an inefficient receptor binding activity of influenza on N-glycolyl sialic acids. Differences in hemagglutinin receptor binding activity due to its specificity to N-acetyl or N-glycolyl cell surface oligosaccharides, density of these cellular receptors and level of negative charges on the cell surface may possibly explain these results, showing influence on the sialidase activity and the fusogenic process. Comparative analysis showed a lack of dependence between the sialidase and fusion activities developed by influenza B viruses. Influenza A viruses at low sialidase titers (<2) also exhibited clearly low hemolysis at pH 5.5 (15.8%), while influenza B viruses with similarly low sialidase titers showed highly variable hemolysis indexes (0.2 to 78.0%). These results support the idea that different virus and cell-associated factors such as those presented above have a significant effect on the multifactorial fusion process