Biology subjects

de Figueiredo, P.

Publications and source records attributed to de Figueiredo, P..

4 recordsLinked to original sources

bioRxiv2021

Host protease activity on bacterial pathogens promotes complement- and antibiotic-directed killing

Our understanding of how the host immune system thwarts bacterial evasive mechanisms remains incomplete. Here, we show that host protease neutrophil elastase acts on Acinetobacter baumannii and Pseudomonas aeruginosa to destroy factors that prevent serum-associated, complement-directed killing. The protease activity also enhances bacterial susceptibility to antibiotics in sera. These findings implicate a new paradigm where host protease activity on bacteria acts synergistically with the host complement system and antibiotics to defeat bacterial pathogens.

microbiology↗

bioRxiv2020

Sub-second heat inactivation of coronavirus

Heat treatment denatures viral proteins that comprise the virion, making virus incapable of infecting a host. Coronavirus (CoV) virions contain single-stranded RNA genomes with a lipid envelope and 4 proteins, 3 of which are associated with the lipid envelope and thus are thought to be easily denatured by heat or surfactant-type chemicals. Prior studies have shown that a temperature of as low as 75 {degrees}C and treatment duration of 15 min can effectively inactivate CoV. The applicability of a CoV heat inactivation method greatly depends on the length of time of a heat treatment and the temperature needed to inactivate the virus. With the goal of finding conditions where sub-second heat exposure of CoV can sufficiently inactivate CoV, we designed and developed a simple system that can measure sub-second heat inactivation of CoV. The system is composed of capillary stainless-steel tubing immersed in a temperature-controlled oil bath followed by an ice bath, through which virus solution can be flowed at various speeds. Flowing virus solution at different speeds, along with a real-time temperature monitoring system, allows the virus to be accurately exposed to a desired temperature for various durations of time. Using mouse hepatitis virus (MHV), a beta-coronavirus, as a model system, we identified that 85.2 {degrees}C for 0.48 s exposure is sufficient to obtain > 5 Log10 reduction in viral titer (starting titer: 5 x 107 PFU/mL), and that when exposed to 83.4 {degrees}C for 0.95 s, the virus was completely inactivated (zero titer, > 6 Log10 reduction). IMPORTANCEThree coronaviruses (CoVs) have now caused global outbreaks within the past 20 years, with the COVID19 pandemic caused by SARS-CoV-2 still ongoing. Methods that can rapidly inactivate viruses, especially CoVs, can play critical roles in ensuring public safety and safeguarding personal health. Heat treatment of viruses to inactive them can be an efficient and inexpensive method, with the potential to be incorporated into various human-occupied spaces. In this work, a simple system that can heat-treat viruses for extremely short period was developed and utilized to show that sub-second exposure of CoV to heat is sufficient to inactivate CoV. This opens up the possibility of developing instruments and methods of disinfecting CoV in diverse settings, including rapid liquid disinfection and airborne virus disinfection. The developed method can also be broadly utilized to assess heat sensitivity of viruses other viral pathogens of interest and develop sub-second rapid heat inactivation approaches.

bioengineering↗

bioRxiv2020

Interactions between fungal hyaluronic acid and host CD44 promotes internalization by recruiting host autophagy proteins to forming phagosomes

Phagocytosis and autophagy play critical roles in immune defense. Cryptococcus neoformans (Cn), a fungal pathogen that causes fatal infection, subverts the host autophagy initiation complex (AIC) and its upstream regulatory proteins, to promote its phagocytosis and intracellular parasitism of host cells. The mechanisms by which the pathogen engages host AIC proteins remain obscure. Here, we show that the recruitment of host AIC proteins to forming phagosomes is dependent upon the activity of CD44, a host cell surface receptor that engages fungal hyaluronic acid (HA). This interaction elevates intracellular Ca2+ concentrations and activates CaMKK{beta} and its downstream target AMPK, which results in activation of ULK1 and the recruitment of AIC components. Moreover, we demonstrate that HA-coated beads efficiently recruit AIC components to phagosomes. Taken together, these findings show that fungal HA plays a critical role in directing the internalization and productive intracellular membrane trafficking of a fungal pathogen of global importance. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=160 SRC="FIGDIR/small/047621v2_ufig1.gif" ALT="Figure 1"> View larger version (44K): org.highwire.dtl.DTLVardef@72f2b9org.highwire.dtl.DTLVardef@9d5a2corg.highwire.dtl.DTLVardef@8b0218org.highwire.dtl.DTLVardef@3698d0_HPS_FORMAT_FIGEXP M_FIG C_FIG In BriefDing et al. reveal that interactions between fungal hyaluronic acid (HA) and host CD44 activate a Ca2+ - CaMKK{beta}-AMPK-ULK1 signaling pathway that recruits autophagy initiation complex components to forming phagosomes to drive fungal internalization. HighlightsO_LIFungal HA interactions with host cells drive a novel non-canonical, ligand-induced, autophagy pathway in phagocytic cells C_LIO_LICryptococcus neoformans recruits host CD44, together with AIC components and regulatory proteins, to forming phagocytic cups to initiate host cell internalization C_LIO_LIFungal HA interactions with CD44 on host cell surfaces elevate intracellular Ca2+ concentrations, leading to activation of CaMKK{beta} C_LIO_LIA Ca2+-CaMKK{beta}-AMPK-ULK1 signaling axis is involved in HA and CD44 induced autophagy protein recruitment during Cn internalization C_LI

microbiology↗

bioRxiv2020

A tractable Drosophila cell system enables rapid identification of Acinetobacter baumannii host factors

AO_SCPLOWBSTRACTC_SCPLOWAcinetobacter baumannii is an important causative agent of nosocomial infections worldwide. The pathogen also readily acquires resistance to antibiotics, and pan-resistant strains have been reported. A. baumannii is widely regarded as an extracellular bacterial pathogen. However, accumulating evidence demonstrates that the pathogen can invade, survive or persist in infected mammalian cells. Unfortunately, the molecular mechanisms controlling these processes remain poorly understood. Here, we show that Drosophila S2 cells provide several attractive advantages as a model system for investigating the intracellular lifestyle of the pathogen, including susceptibility to bacterial intracellular replication and limited infection-induced host cell death. We also show that the Drosophila system can be used to rapidly identify host factors, including MAP kinase proteins, which confer susceptibility to intracellular parasitism. Finally, analysis of the Drosophila system suggested that host proteins that regulate organelle biogenesis and membrane trafficking contribute to regulating the intracellular lifestyle of the pathogen. Taken together, these findings establish a novel model system for elucidating interactions between A. baumannii and host cells, define new factors that regulate bacterial invasion or intracellular persistence, and identify subcellular compartments in host cells that interact with the pathogen.

microbiology↗