Mycobacterium tuberculosis and M. smegmatis form drug-tolerant biofilms through dedicated genetic programs. In support of a stepwise process regulating biofilm production in mycobacteria, it was shown elsewhere that lsr2 participates in intercellular aggregation, while groEL1 was required for biofilm maturation in M. smegmatis. Here, by means of RNA-Seq, we monitored the early steps of biofilm production in M. bovis BCG, to distinguish intercellular aggregation from attachment to a surface. Genes encoding for the transcriptional regulators dosR and BCG0114 (Rv0081) were significantly regulated and responded differently to intercellular aggregation and surface attachment. Moreover, a M. tuberculosis H37Rv deletion mutant in the Rv3134c-dosS-dosR regulon, formed less biofilm than wild type M. tuberculosis, a phenotype reverted upon reintroduction of this operon into the mutant. Combining RT-qPCR with microbiological assays (colony and surface pellicle morphologies, biofilm quantification, Ziehl-Neelsen staining, growth curve and replication of planktonic cells), we found that BCG0642c affected biofilm production and replication of planktonic BcG, whereas ethR affected only phenotypes linked to planktonic cells despite its downregulation at the intercellular aggregation step. our results provide evidence for a stage-dependent expression of genes that contribute to biofilm production in slow-growing mycobacteria. In nature, microbial species are often found within a matrix, forming multicellular communities that attach to surfaces or air-liquid interfaces, called biofilms 1. Biofilms are relevant to human health, as a majority of bacterial pathogens employ these structures to modify the host response 2 contributing to persistence 3. In this regard, a link exists between in vitro biofilm production and in vivo persistence for BCG 4 and M. tuberculosis 5. Biofilm formation occurs via a series of well-defined steps. These include the attachment of single-cell planktonic microbes onto a substratum; aggregation and growth of the adherent cells into three-dimensionally organized structures; and encapsulation of the structures by a self-produced matrix of extracellular polymeric substance 1 .
Immunotherapies based on antibody fragments have been developed and applied to human diseases, describing novel antibody formats. The vNAR domains have a potential therapeutic use related to their unique properties. This work used a non-immunized Heterodontus francisci shark library to obtain a vNAR with recognition of TGF-β isoforms. The isolated vNAR T1 selected by phage display demonstrated binding of the vNAR T1 to TGF-β isoforms (-β1, -β2, -β3) by direct ELISA assay. These results are supported by using for the first time the Single-Cycle kinetics (SCK) method for Surface plasmon resonance (SPR) analysis for a vNAR. Also, the vNAR T1 shows an equilibrium dissociation constant (KD) of 9.61 × 10–8 M against rhTGF-β1. Furthermore, the molecular docking analysis revealed that the vNAR T1 interacts with amino acid residues of TGF-β1, which are essential for interaction with type I and II TGF-β receptors. The vNAR T1 is the first pan-specific shark domain reported against the three hTGF-β isoforms and a potential alternative to overcome the challenges related to the modulation of TGF-β levels implicated in several human diseases such as fibrosis, cancer, and COVID-19.
Zika virus (ZIKV) has gained great importance worldwide since the past epidemic that occurred in 2015 in Brazil. Early identification of ZIKV is critical to minimize transmission and prevents potentially devastating consequences, including microcephaly in neonates of infected women, congenital blindness, or Guillain-Barré Syndrome. However, this is not an easy task, considering that approximately 80% of ZIKV infection cases are asymptomatic or oligosymptomatic, there are diverse modes of transmission (vertical transmission is through vectors and horizontal transmission through blood, saliva, semen, and urine from infected people), and the fact that ZIKV has a high identity percentage with other cocirculating Flaviviruses such as dengue. Here, we review ZIKV diagnostic methods, with special emphasis on the development of point-of-care diagnostic assays, since these devices commonly have two important advantages: they provide prompt screening and are affordable.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.