Epidemiology of yellow fever virus in humans,arthropods, and non-human primates in sub-Saharan Africa: A systematic review and meta-analysis

Yellow fever (YF) has re-emerged in the last two decades causing several outbreaks in endemic countries and spreading to new receptive regions. This changing epidemiology of YF creates new challenges for global public health efforts. Yellow fever is caused by the yellow fever virus (YFV) that circulates between humans, the mosquito vector, and non-human primates (NHP). In this systematic review and meta-analysis, we review and analyse data on the case fatality rate (CFR) and prevalence of YFV in humans, and on the prevalence of YFV in arthropods, and NHP in sub-Saharan Africa (SSA). We performed a comprehensive literature search in PubMed, Web of Science, African Journal Online, and African Index Medicus databases. We included studies reporting data on the CFR and/or prevalence of YFV. Extracted data was verified and analysed using the random effect meta-analysis. We conducted subgroup, sensitivity analysis, and publication bias analyses using the random effect meta-analysis while I² statistic was employed to determine heterogeneity. This review was registered with PROSPERO under the identification CRD42021242444. The final meta-analysis included 55 studies. The overall case fatality rate due to YFV was 31.1% (18.3–45.4) in humans and pooled prevalence of YFV infection was 9.4% (6.9–12.2) in humans. Only five studies in West and East Africa detected the YFV in mosquito species of the genus Aedes and in Anopheles funestus. In NHP, YFV antibodies were found only in members of the Cercopithecidae family. Our analysis provides evidence on the ongoing circulation of the YFV in humans, Aedes mosquitoes and NHP in SSA. These observations highlight the ongoing transmission of the YFV and its potential to cause large outbreaks in SSA. As such, strategies such as those proposed by the WHO’s Eliminate Yellow Fever Epidemics (EYE) initiative are urgently needed to control and prevent yellow fever outbreaks in SSA.     

Cell-penetrating peptides: from molecular mechanisms to therapeutics

The recent discovery of new potent therapeutic molecules which do not reach the clinic due to poor delivery and low bioavailability have made the delivery of molecules a keystone in therapeutic development. Several technologies have been designed to improve cellular uptake of therapeutic molecules, including CPPs (cell-penetrating peptides), which represent a new and innovative concept to bypass the problem of bioavailability of drugs. CPPs constitute very promising tools and have been successfully applied for in vivo. Two CPP strategies have been described to date; the first one requires chemical linkage between the drug and the carrier for cellular drug internalization, and the second is based on the formation of stable complexes with drugs, depending on their chemical nature. The Pep and MPG families are short amphipathic peptides, which form stable nanoparticles with proteins and nucleic acids respectively. MPG- and Pep-based nanoparticles enter cells independently of the endosomal pathway and efficiently deliver cargoes, in a fully biologically active form, into a large variety of cell lines, as well as in animal models. This review focuses on the structure-function relationship of non-covalent MPG and Pep-1 strategies, and their requirement for cellular uptake of biomolecules and applications in cultured cells and animal models.     

Drug resistance-conferring mutations in Mycobacterium tuberculosis from Madang, Papua New Guinea

ABSTRACT: BACKGROUND: Monitoring drug resistance in Mycobacterium tuberculosis is essential to curb the spread of tuberculosis (TB). Unfortunately, drug susceptibility testing is currently not available in Papua New Guinea (PNG) and that impairs TB control in this country. We report for the first time M. tuberculosis mutations associated with resistance to first and second-line anti-TB drugs in Madang, PNG. A molecular cluster analysis was performed to identify M. tuberculosis transmission in that region. RESULTS: Phenotypic drug susceptibility tests showed 15.7% resistance to at least one drug and 5.2% multidrug resistant (MDR) TB. Rifampicin resistant strains had the rpoB mutations D516F, D516Y or S531L; isoniazid resistant strains had the mutations katG S315T or inhA promoter C15T; streptomycin resistant strains had the mutations rpsL K43R, K88Q, K88R), rrs A514C or gidB V77G. The molecular cluster analysis indicated evidence for transmission of resistant strain. CONCLUSIONS: We observed a substantial rate of MDR-TB in the Madang area of PNG associated with mutations in specific genes. A close monitoring of drug resistance is therefore urgently required, particularly in the presence of drug-resistant M. tuberculosis transmission. In the absence of phenotypic drug susceptibility testing in PNG, molecular assays for drug resistance monitoring would be of advantage.     

Absence of DICER in Monocytes and Its Regulation by HIV-1

MicroRNAs (miRNAs) are a class of small RNA molecules that function to control gene expression and restrict viral replication in host cells. The production of miRNAs is believed to be dependent upon the DICER enzyme. Available evidence suggests that in T lymphocytes, HIV-1 can both suppress and co-opt the host''s miRNA pathway for its own benefit. In this study, we examined the state of miRNA production in monocytes and macrophages as well as the consequences of viral infection upon the production of miRNA. Monocytes in general express low amounts of miRNA-related proteins, and DICER in particular could not be detected until after monocytes were differentiated into macrophages. In the case where HIV-1 was present prior to differentiation, the expression of DICER was suppressed. MicroRNA chip results for RNA isolated from transfected and treated cells indicated that a drop in miRNA production coincided with DICER protein suppression in macrophages. We found that the expression of DICER in monocytes is restricted by miR-106a, but HIV-1 suppressed DICER expression via the viral gene Vpr. Additionally, analysis of miRNA expression in monocytes and macrophages revealed evidence that some miRNAs can be processed by both DICER and PIWIL4. Results presented here have implications for both the pathology of viral infections in macrophages and the biogenesis of miRNAs. First, HIV-1 suppresses the expression and function of DICER in macrophages via a previously unknown mechanism. Second, the presence of miRNAs in monocytes lacking DICER indicates that some miRNAs can be generated by proteins other than DICER.     

The impact of autophagy on cell death modalities in CRL-5876 lung adenocarcinoma cells after their exposure to γ-rays and/or erlotinib

In most patients with lung cancer radiation treatment is used either as single agent or in combination with radiosensitizing drugs. However, the mechanisms underlying combined therapy and its impact on different modes of cell death have not yet been fully elucidated. We aimed to examine effects of single and combined treatments with γ-rays and erlotinib on radioresistant CRL-5876 human lung adenocarcinoma cells with particular emphasis on cell death. CRL-5876 cells were treated with γ-rays and/or erlotinib and changes in cell cycle, DNA repair dynamics, ultrastructure, nuclear morphology and protein expression were monitored at different time points. To reveal the relationship between types of cell death that arise after these treatments, autophagy was blocked with chloroquine. We found that higher dose of γ-rays causes G2/M arrest while adding of erlotinib to this treatment decreases the number of cells in S phase. Impact of erlotinib on kinetics of disappearance of irradiation-induced DNA double strand breaks is reflected in the increase of residual γ-H2AX foci after 24 h. γ-rays provoke cytoprotective autophagy which precedes development of senescence. Erlotinib predominantly induces apoptosis and enlarges the number of apoptotic cells in the irradiated CRL-5876 cells. Chloroquine improved cytotoxicity induced by radiation and erlotinib, increased apoptosis and decreased senescence in the CRL-5876 cells. The results obtained on CRL-5876 cells indicate significant radiosensitizing effect of erlotinib and suggest that chloroquine in the combination with the above treatments may have an additional antitumor effect in lung adenocarcinoma.     

Structural basis for the phototoxicity of the fluorescent protein KillerRed

The red fluorescent protein KillerRed, engineered from the hydrozoan chromoprotein anm2CP, has been reported to induce strong cytotoxicity through the chromophore assisted light inactivation (CALI) effect. Here, we present the X-ray structures of KillerRed in its native and bleached states. A long water-filled channel is revealed, connecting the methylene bridge of the chromophore to the solvent. This channel facilitates the transit of oxygen and of reactive oxygen species (ROS) formed by reaction with the excited chromophore. The functional roles of key mutations used to produce KillerRed are discussed, strong chromophore distortions in the bleached state are revealed, and mechanisms for ROS production and self protection are proposed. The presence of a partially mature, photo-resistant, green-emitting state is characterized, which accounts for enhanced CALI by “pre-bleached” KillerRed.     

MacroH2A histone variants limit chromatin plasticity through two distinct mechanisms

MacroH2A histone variants suppress tumor progression and act as epigenetic barriers to induced pluripotency. How they impart their influence on chromatin plasticity is not well understood. Here, we analyze how the different domains of macroH2A proteins contribute to chromatin structure and dynamics. By solving the crystal structure of the macrodomain of human macroH2A2 at 1.7 Å, we find that its putative binding pocket exhibits marked structural differences compared with the macroH2A1.1 isoform, rendering macroH2A2 unable to bind ADP‐ribose. Quantitative binding assays show that this specificity is conserved among vertebrate macroH2A isoforms. We further find that macroH2A histones reduce the transient, PARP1‐dependent chromatin relaxation that occurs in living cells upon DNA damage through two distinct mechanisms. First, macroH2A1.1 mediates an isoform‐specific effect through its ability to suppress PARP1 activity. Second, the unstructured linker region exerts an additional repressive effect that is common to all macroH2A proteins. In the absence of DNA damage, the macroH2A linker is also sufficient for rescuing heterochromatin architecture in cells deficient for macroH2A.