Nanoparticles and Other Nanostructures and the Control of Pathogens: From Bench to Vaccines.

Parasites and microorganisms (protozoa, bacteria, and viruses) are still a concern despite progress in hygiene and anti-infectious therapy [...].

The Impact of Multiple Functional Layers in the Structure of Magnetic Nanoparticles and Their Influence on Albumin Interaction.

In nanomedicine, hybrid nanomaterials stand out for providing new insights in both the diagnosis and treatment of several diseases. Once administered, engineered nanoparticles (NPs) interact with biological molecules, and the nature of this interaction might directly interfere with the biological fate and action of the NPs. In this work, we synthesized a hybrid magnetic nanostructure, with antibacterial and antitumoral potential applications, composed of a magnetite core covered by silver NPs, and coated with a modified chitosan polymer. As magnetite NPs readily oxidize to maghemite, we investigated the structural properties of the NPs after addition of the two successive layers using Mössbauer spectroscopy. Then, the structural characteristics of the NPs were correlated to their interaction with albumin, the major blood protein, to evidence the consequences of its binding on NP properties and protein retention. Thermodynamic parameters of the NPs-albumin interaction were determined. We observed that the more stable NPs (coated with modified chitosan) present a lower affinity for albumin in comparison to pure magnetite and magnetite/silver hybrid NPs. Surface properties were key players at the NP-biological interface. To the best of our knowledge, this is the first study that demonstrates a correlation between the structural properties of complex hybrid NPs and their interaction with albumin.

Single wall and multiwall carbon nanotubes induce different toxicological responses in rat alveolar macrophages.

Human exposure to airborne carbon nanotubes (CNT) is increasing because of their applications in different sectors; therefore, they constitute a biological hazard. Consequently, developing studies on CNT toxicity become a necessity. CNTs can have different properties in term of length, size and charge. Here, we compared the cellular effect of multiwall (MWCNTs) and single wall CNTs (SWCNTs). MWCNTs consist of multiple layers of graphene, while SWCNTs are monolayers. The effects of MWCNTs and SWCNTs were evaluated by the water-soluble tetrazolium salt cell proliferation assay on NR8383 cells, rat alveolar macrophage cell line (NR8383). After 24 hours of exposure, MWCNTs showed higher toxicity (50% inhibitory concentration [IC50 ] = 3.2 cm2 /cm2 ) than SWCNTs (IC50  = 44 cm2 /cm2 ). Only SWCNTs have induced NR8383 cells apoptosis as assayed by flow cytometry using the annexin V/IP staining test. The expression of genes involved in oxidative burst (Ncf1), inflammation (Nfκb, Tnf-α, Il-6 and Il-1ß), mitochondrial damage (Opa) and apoptotic balance (Pdcd4, Bcl-2 and Casp-8) was determined. We found that MWCNT exposure predominantly induce inflammation, while SWCNTs induce apoptosis and impaired mitochondrial function. Our results clearly suggest that MWCNTs are ideal candidates for acute inflammation induction. In vivo studies are required to confirm this hypothesis. However, we conclude that toxicity of CNTs is dependent on their physical and chemical characteristics.

Encapsulation of S-nitrosoglutathione: a transcriptomic validation.

OBJECTIVE: S-nitrosogluthatione (GSNO), a S-nitrosothiol, is a commonly used as nitric oxide (NO•) donor. However, its half-life is too short for a direct therapeutic use. To protect and ensure a sustained release of NO•, the encapsulation of GSNO into nanoparticles may be an interesting option. METHODS: In this work, we have investigated the early (4 h) and late (24 h) transcriptomic response of THP-1 human monocytes cells to two doses (1.4 and 6 µM) of either free or Eudragit® nano-encapsulated GSNO using RNA microarray. RESULTS: After exposure to free GSNO, genes mainly involved in apoptosis, cell differentiation, immune response and metabolic processes were differentially expressed. Although, cells exposed to free or encapsulated GSNO behave differently, activation of genes involved in blood coagulation, immune response and cell cycle was observed in both conditions. CONCLUSIONS: These results suggest that the encapsulation of low doses of GSNO into Eudragit® nanoparticles leads to a progressive release of GSNO making this compound a possible oral therapy for several biomedical applications like inflammatory bowel diseases.

Human monocyte response to S-nitrosoglutathione-loaded nanoparticles: uptake, viability, and transcriptome.

S-Nitrosoglutathione (GSNO) is a good candidate for nitric oxide (NO(•)) delivery, and its nanoformulation improves NO(•) stability and bioavailability. We have compared the effect of empty Eudragit nanoparticles (eENP), GSNO-loaded ENP (gENP), and free GSNO on THP-1 human monocytic cell line. We investigated cellular viability and growth by WST-1 and trypan blue tests. ENP uptake was studied using transmission electron microscopy, confocal microscopy, and flow cytometry. Transcriptomic profiles were obtained using microarray. ENP entered cells by clathrin- and caveolae-mediated endocytosis. Exposure to either free GSNO or gENP induced an activation of genes from the same clusters, in favor of intracellular delivery of GSNO by ENP. GSNO nanoformulation might be a therapeutic option for NO(•) delivery.

Efficacy and safety of artemether + lumefantrine, artesunate + sulphamethoxypyrazine-pyrimethamine and artesunate + amodiaquine and sulphadoxine-pyrimethamine + amodiaquine in the treatment of uncomplicated falciparum malaria in Bangui, Central African Republic: a randomized trial.

BACKGROUND: The efficacy of artemisinin-based combination therapy (ACT) has been established. The objective of the present study was to compare the efficacy and safety in the Central African Republic (CAR) of three commercially available artemisinin-based combinations, artemether + lumefantrine (AL), artesunate + sulphamethoxypyrazine-pyrimethamine (AS-SMP) and artesunate + amodiaquine (AS-AQ), with those of sulphadoxine-pyrimethamine + amodiaquine (SP-AQ), which was the first-line reference treatment in the country from 2004, until it was replaced by ACT in 2006 in accordance with changes in international recommendations based on resistance identified in other regions. METHODS: Children aged six to 59 months with uncomplicated Plasmodium falciparum malaria were recruited in Bangui, the capital of the CAR. The 251 patients selected were randomly assigned to receive AL (n = 60), AS-SMP (n = 58), AS-AQ (n = 68) or SP-AQ (n = 65) and were followed up for 28 days. Clinical outcome was classified according to the standard 2003 World Health Organization protocol. RESULTS: At day 28, the cure rates in a per-protocol analysis were 92% (48/52) with AL, 93% (50/54) with AS-SMP, 93% (55/59) with AS-AQ and 100% (57/57) with SP-AQ, with no statistically significant difference between the four treatments. Defervescence was significantly faster with AS-AQ than with AL (p <0.035). Fatigue was reported significantly more frequently by patients receiving AQ than by those treated with AS-SMP or AL (p = 0.006). All the other adverse events reported were mild, and no significant difference was noted by treatment. CONCLUSION: The three artemisinin-bsed combinations show similar, satisfactory results, comparable to that with SP-AQ. This evaluation is the first conducted in CAR since the official introduction of ACT. It should guide the National Malaria Control Programme in choosing the appropriate ACT for treatment of uncomplicated P. falciparum malaria in the future.

Viability and gene expression responses to polymeric nanoparticles in human and rat cells.

Applications of polymeric nanoparticles (NP) in medical fields are rapidly expanding. However, the influence of polymeric NP on cell growth and functions is widely underestimated. Therefore, we have studied cell and polymeric NP interactions by addressing two cell types with two endpoints (viability and gene expressions). Rat NR8383 and human THP-1 monocytic cell lines were exposed to 6 to 200 µg/mL of Eudragit(®) RL NP for 24 h, and cellular viability was estimated using MTT, WST-1, and trypan blue tests. A decrease of viability was observed with NR8383 cells (down to 70% for 200 µg/mL), and on the contrary, an increase with THP-1 cells (up to 140% for 200 µg/mL). Differential expression of genes involved in oxidative damage (NCF1), inflammation (NFKB, TNFA, IL6, IL1B), autophagy (ATG16L), and apoptotic balance (PDCD4, BCL2, CASP8) was analyzed. ATG16L, BCL2, and TNFA were up-regulated in NR8383 cells, which are consistent with an induction of autophagy and inflammation. On the other hand, NCF1, NFKB, and IL1B were down-regulated in THP-1 cells, which may contribute to explain the increase of cellular viability. Our results show that (1) the toxic potency of NP is dependent on the cellular model used and (2) mechanistic toxicology should be the corner stone for the evaluation of NP hazard.

High genetic diversity of Newcastle disease virus in poultry in West and Central Africa: cocirculation of genotype XIV and newly defined genotypes XVII and XVIII.

Despite rampant Newcastle disease virus (NDV) outbreaks in Africa for decades, the information about the genetic characteristics of the virulent strains circulating in West and Central Africa is still scarce. In this study, 96 complete NDV fusion gene sequences were obtained from poultry sampled in Cameroon, Central African Republic, Côte d'Ivoire, and Nigeria between 2006 and 2011. Based on rational criteria recently proposed for the classification of NDV strains into classes, genotypes, and subgenotypes, we revisited the classification of virulent strains, in particular those from West and Central Africa, leading to their grouping into genotype XIV and newly defined genotypes XVII and XVIII, each with two subgenotypes. Phylogenetic analyses revealed that several (sub)genotypes are found in almost every country. In Cameroon, most strains were related to vaccine strains, but a single genotype XVII strain was also found. Only three highly similar genotype XVII strains were detected in Central African Republic. Subgenotypes XVIIa, XVIIIa, and XVIIIb cocirculated in Côte d'Ivoire, while subgenotypes XIVa, XIVb, XVIIa, XVIIb, and XVIIIb were found in Nigeria. While these genotypes are so far geographically restricted, local and international trade of domestic and exotic birds may lead to their spread beyond West and Central Africa. A high genetic diversity, mutations in important neutralizing epitopes paired with suboptimal vaccination, various levels of clinical responses of poultry and wild birds to virulent strains, strains with new cleavage sites, and other genetic modifications found in these genotypes tend to undermine and complicate NDV management in Africa.

Cross-sectional study of hepatitis B virus infection in rural communities, Central African Republic.

BACKGROUND: As most data on hepatitis in resource-poor countries relate to urban communities, surveys in the rural environment are necessary to determine the 'true' prevalence of these viral infections. We undertook a survey to determine the prevalence of hepatitis B virus (HBV) infection in an apparently healthy rural population in the Central African Republic (CAR). METHODS: The cross-sectional study was based on dried blood spots (DBS) from 273 people recruited in four prefectures (Lobaye, Nana-Mambéré, Ouham and Ouaka). Eluates from DBS were tested with commercial ELISA kits to detect markers of HBV infection. DBS were directly used for DNA extraction, followed by PCR and genotyping based on preS/S gene sequences. RESULTS: The overall prevalence of HBc antibodies was 27.1% (Lobaye 29%, Nana-Mambéré 28%, Ouaka 29% and Ouham 23%) and that of HBsAg was 10.6% (Lobaye 9%, Nana-Mambéré 9%, Ouaka 19% and Ouham 8%), with no statistically significant difference among the surveyed communities. Nineteen sequences obtained from 74 anti-HBc-positive patients all belonged to genotype E. Risk factor analysis of HBV infection pointed to sexual transmission of the virus. CONCLUSION: The prevalence of HBV is high in rural communities in the CAR and comparable to that observed in urban areas. In addition, genotype E is prevalent in these areas. These findings underline the importance of instituting a programme of active HBV surveillance and vaccination of the population.

COVID-19 Genomic Surveillance in Bangui (Central African Republic) Reveals a Landscape of Circulating Variants Linked to Validated Antiviral Targets of SARS-CoV-2 Proteome.

Since its outbreak, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) spread rapidly, causing the Coronavirus Disease 19 (COVID-19) pandemic. Even with the vaccines' administration, the virus continued to circulate due to inequal access to prevention and therapeutic measures in African countries. Information about COVID-19 in Africa has been limited and contradictory, and thus regional studies are important. On this premise, we conducted a genomic surveillance study about COVID-19 lineages circulating in Bangui, Central African Republic (CAR). We collected 2687 nasopharyngeal samples at four checkpoints in Bangui from 2 to 22 July 2021. Fifty-three samples tested positive for SARS-CoV-2, and viral genomes were sequenced to look for the presence of different viral strains. We performed phylogenetic analysis and described the lineage landscape of SARS-CoV-2 circulating in the CAR along 15 months of pandemics and in Africa during the study period, finding the Delta variant as the predominant Variant of Concern (VoC). The deduced aminoacidic sequences of structural and non-structural genes were determined and compared to reference and reported isolates from Africa. Despite the limited number of positive samples obtained, this study provides valuable information about COVID-19 evolution at the regional level and allows for a better understanding of SARS-CoV-2 circulation in the CAR.

Epidemiology of chicken anemia virus in Central African Republic and Cameroon.

BACKGROUND: Although chicken anemia virus (CAV) has been detected on all continents, little is known about this virus in sub-Saharan Africa. This study aimed to detect and characterize CAV for the first time in Central African Republic and in Cameroon. RESULTS: An overall flock seroprevalence of 36.7% was found in Central African Republic during the 2008-2010 period. Virus prevalences were 34.2% (2008), 14.3% (2009) and 10.4% (2010) in Central African Republic and 39% (2007) and 34.9% (2009) in Cameroon. CAV DNA was found in cloacal swabs of 76.9% of seropositive chickens, suggesting that these animals excreted the virus despite antibodies. On the basis of VP1 sequences, most of the strains in Central African Republic and Cameroon belonged to 9 distinct phylogenetic clusters at the nucleotide level and were not intermixed with strains from other continent. Several cases of mixed infections in flocks and individual chickens were identified. CONCLUSIONS: Our results suggest multiple introductions of CAV in each country that later spread and diverged locally. Mixed genotype infections together with the observation of CAV DNA in cloacal samples despite antibodies suggest a suboptimal protection by antibodies or virus persistence.

Rational case management of malaria with a rapid diagnostic test, Paracheck Pf®, in antenatal health care in Bangui, Central African Republic.

BACKGROUND: Both treatment and prevention strategies are recommended by the World Health Organization for the control of malaria during pregnancy in tropical areas. The aim of this study was to assess use of a rapid diagnostic test for prompt management of malaria in pregnancy in Bangui, Central African Republic. METHODS: A cohort of 76 pregnant women was screened systematically for malaria with ParacheckPf® at each antenatal visit. The usefulness of the method was analysed by comparing the number of malaria episodes requiring treatment in the cohort with the number of prescriptions received by another group of pregnant women followed-up in routine antenatal care. RESULTS: In the cohort group, the proportion of positive ParacheckPf® episodes during antenatal clinics visits was 13.8%, while episodes of antimalarial prescriptions in the group which was followed-up routinely by antenatal personnel was estimated at 26.3%. Hence, the relative risk of the cohort for being prescribed an antimalarial drug was 0.53. Therefore, the attributable fraction of presumptive treatment avoided by systematic screening with ParacheckPf® was 47%. CONCLUSIONS: Use of a rapid diagnostic test is useful, affordable and easy for adequate treatment of malaria in pregnant women. More powerful studies of the usefulness of introducing the test into antenatal care are needed in all heath centres in the country and in other tropical areas.

Rubella epidemiology in the Central African Republic, 2015-2016 and molecular characterization of virus strains from 2008-2016.

OBJECTIVES: Rubella cases in the Central African Republic (CAF) are currently identified during measles surveillance. This study aimed to investigate rubella epidemiology between 2015 and 2016 and to provide baseline genotype data for monitoring future rubella control efforts. METHODS: 831 measles IgM negative or equivocal sera from 2015/2016 were tested for rubella IgM antibodies and 350 rubella IgM positive sera collected between 2008 and 2016 were selected for PCR and sequencing. RESULTS: 411 of the 831 sera (49.5%) were rubella IgM positive and most cases (n=391, 95.1%) occurred between January and April. Most patients were between 5 and 9 years old (50.2%) and more than half of the rubella cases (56.7%) originated from the capital Bangui. Genotype information was obtained for 37 of the 350 selected rubella IgM-positive specimens, with the majority of the patients originating from Bangui (n=24, 64.9%) and sequences covering all years except 2009. Phylogenetic analysis identified genotypes 1E (n=12), 1G (n=5) and 2B (n=20), with 2B being detected from 2014 onwards. CONCLUSIONS: Our study confirmed the important role of rubella as a rash and fever disease in CAF and provided comprehensive data on rubella epidemiology and the first information on rubella genotypes in the country.

The prevalence of hepatitis B virus markers in a cohort of students in Bangui, Central African Republic.

BACKGROUND: Hepatitis B virus (HBV) is the major cause of chronic hepatitis, cirrhosis, and hepatocellular carcinoma. The global epidemiological scenario of HBV infection has been changing rapidly over the last two decades due to an effective immunization programme initiated by the World Health Organization. The objective of this study is to estimate the prevalence of HBV in apparently healthy young people and to identify the risk factors of transmission of the HBV among this population in Bangui. METHODS: Dried blood Spots from 801 adolescent high school and young adult university students were prepared by spotting a drop of whole blood (4 spots) from the same fingerprick onto Whatman filter paper. A blood sample aliquot eluted from DBS was then processed with commercial ELISA tests (Abbott Murex, Dartfort, UK) to detect HBsAg antigen, Anti-HBc and Anti-HBs antibodies). RESULTS: The overall prevalence was 42.3% for antibody to hepatitis B core antigen, 15.5% for HBsAg of which 1.3% of HBsAg alone. HBV familial antecedents, sexual activity and socioeconomic conditions were the main risk factors of HBV infection encountered in the adolescents and young adults. CONCLUSION: These results show for the first time the high prevalence of HBV in apparently healthy young people in Bangui. This high prevalence is age- and sex-independent. Transmission risk factors were a familial antecedent of HBV, no utilisation of condoms and public scholarship. To lower HBV prevalence, an adequate program of active screening and vaccination for adolescents and young adults should be implemented, along with a universal immunization program.

Proteomic analysis of bronchoalveolar lavage fluid in rat exposed to TiO2 nanostructured aerosol by inhalation.

The pulmonary toxicological properties of inhaled titanium dioxide were studied using bronchoalveolar lavage fluid (BALF) cytology and proteomics analyses. Fischer 344 rats were exposed to 10 mg/m3 of TiO2 nanostructured aerosol by nose-only inhalation for 6 h/day, 5 days/week for 4 weeks. Lung samples were collected up to 180 post-exposure days. As previously described, cytological analyses of BALF showed a strong inflammatory response up to 3 post-exposure days, which persisted however, at a lower intensity up to 180 days. In addition, using Multidimensional Protein Identification Technology (MudPIT), we identified a total of 107, 50 and 45 proteins (UniprotKB identifiers) differentially expressed in exposed rats immediately, 3 and 180 days after the end of exposure respectively. Increased levels of inflammatory proteins, members of proteasome, various histones, proteins involved in cytoskeleton organization, were noticed up to 3 days (short-term response). Some of these proteins were linked with Neutrophil Extracellular Trap formation (NETosis). Long-term response was also characterized by a persistent altered expression of proteins up to 180 days. Altogether, these results suggest that exposure to low toxicity low solubility nanomaterials such as TiO2 may induce long-term changes in the pulmonary protein expression pattern of which the physio-pathological consequences are unknown. SIGNIFICANCE: This paper describes in rats, at the pulmonary level, the effects of inhaled nanostructured aerosol of TiO2 on the secreted proteins found in the broncho-alveolar space by comparing the proteomic profile in broncho-alveolar lavage fluid supernatants of control and exposed animals. This work brings new insights about the early events occurring following the end of exposure and suggests the formation of Neutrophil Extracellular Traps (NETosis) that could be interpret as a potential early mechanism of defense against TiO2 nanoparticles. This work also describes the long term effects (180 post-exposure days) of such an exposure and the change in secreted protein expression in the absence of significant histopathological modifications.

Macrophage culture as a suitable paradigm for evaluation of synthetic vitreous fibers.

The ultimate goal of toxicologic investigation of synthetic vitreous fibers (SVFs) is to provide essential input for the assessment of human risk to their exposure. Toxicity of mineral fibers is usually evaluated by testing biopersistence in rodent model. However, a cellular model would be much appreciated in order to reduce, refine, and replace animal models. Pulmonary disorders triggered by inhalation of occupational or environmental mineral particulates can be the endpoints of a chronic inflammatory process in which alveolar macrophages (AMs) play a crucial role. Depending on the type of SVF involved, phagocytosis of fiber leads to activation of macrophages, resulting in release of fiber components and potent mediators, such as reactive oxygen or nitrogen species and cytokines. As a matter of fact, macrophages should be the cells of choice since SVF toxicity is the consequence of fibers and alveolar macrophages interaction. Today, monocytes and macrophages culture are firmly established as a paradigm in toxicology when several endpoints are assayed in macrophages: (1) fiber durability, (2) fiber surface changes, (3) oxidative stress and genotoxicity in macrophage, and (4) macrophage cell viability and apoptosis. This article is a review of up-to-date knowledge of in vitro studies involving macrophages, and assesses endpoints of macrophage toxicity with an emphasis on (1) dissolution, (2) scanning electron microscopy analysis, (3) cytotoxicity, and (4) gene expression.

Acute bacterial meningitis at the 'Complexe Pédiatrique' of Bangui, Central African Republic.

To precis the aetiologies of children meningitis and the susceptibility to antibiotics of bacteria responsible for meningitis in Bangui, we conducted a prospective study between October 2004 and September 2005, at the 'Complexe Pédiatrique de Bangui', Central African Republic (CAR). Children from 1 day to 16 years with suspected meningitis and who underwent a lumbar puncture were enrolled. Gram staining, culture on chocolate blood medium, cell count, biochemistry (protein level, glucose ratio), capsular antigen detection were performed for each cerebrospinal fluid. MICs were determined by the E-test method. Four hundred and seventeen patients were enrolled during the study period; 130 were proven acute bacterial meningitis and 37 probable bacterial meningitis. Among proven bacterial meningitis, Streptococcus pneumoniae was the most common organism responsible for meningitis (62 cases, 48%) followed by Haemophilus influenzae (46 cases, 35%) and by Neisseria meningitidis and Salmonella sp. (8 cases, 6% each). Ninety-four percent and 96% of S. pneumoniae strains tested remain susceptible to benzylpenicilline and chloramphenicol, respectively. A beta-lactamase was detected in 92% of H. influenzae strains tested. However, MICs 50% and 90% for amoxicillin were found to be 1 and 4 mg/l, respectively and 33% of these strains were resistant to chloramphenicol. The global mortality rate was 35% (59/167). This mortality rate was 47% for S. pneumoniae, 33% for H. influenzae, 62% for Salmonella sp. and 13% for N. meningitidis. The probabilistic treatment with ampicillin and chloramphenicol usually administered for children meningitis in Bangui must be reconsidered particularly in cases of H. influenzae meningitis. It is of importance to reduce the presentation delays of children with suspected meningitis in Bangui. The H. influenzae b immunization would allow a dramatic reduction of meningitis cases and deaths in Central African children.

Central African Republic is part of the West-African hepatitis B virus genotype E crescent.

BACKGROUND: Recent studies have shown that Hepatitis B virus (HBV) genotype E predominates in a vast crescent in West-Africa spanning from Senegal to Angola. OBJECTIVES: To determine whether HBV strains in the Central African Republic (CAR) belong predominately to the homogeneous West-African genotype E or whether they are more closely related to genotypes found in East Africa. STUDY DESIGN: Serum samples were randomly collected from 196 patients admitted with symptoms of acute or chronic hepatitis to the Central Hospital in Bangui. Thirty complete and 36 partial sequences of HBV strains were obtained. RESULTS: Ninety-four percent (62/66) of the strains belonged to genotype E, while genotype A1, most closely related to a strain from Tanzania and genotype D were detected in only one and three samples, respectively. One strain presented a recombination between the S and X gene of a genotype E precursor and a partial PreC/C gene of a genotype D precursor. CONCLUSIONS: Genotype E is predominant in CAR with little overlap with genotypes from Eastern Africa, extending the West-African HBV genotype E crescent further to the East.