Bioinspired Antimicrobial PLA with Nanocones on the Surface for Rapid Deactivation of Omicron SARS-CoV-2.

Bioinspired bactericidal surfaces are artificial surfaces that mimic the nanotopography of insect wings and are capable of inhibiting microbial growth by a physicomechanical mechanism. The scientific community has considered them an alternative method to design polymers with surfaces that inhibit bacterial biofilm formation, suitable for self-disinfectant medical devices. In this contribution, poly(lactic acid) (PLA) with nanocone patterns was successfully produced by a novel two-step procedure involving copper plasma deposition followed by argon plasma etching. According to reverse transcription-quantitative polymerase chain reaction tests, the bioinspired PLA nanostructures display antiviral performance to inactivate infectious Omicron severe acute respiratory syndrome coronavirus 2 particles, reducing the amount of the viral genome to less than 4% in just 15 min due to a possible combined effect of mechanical and oxidative stress. The bioinspired antiviral PLA can be suitable for designing personal protection equipment to prevent the transmission of contagious viral diseases, such as Coronavirus Disease 2019.

Delta SARS-CoV-2 inactivation and bactericidal performance of cotton wipes decorated with TiO2/Ag nanoparticles like Brazilian heavy-fruited Myrciaria cauliflora.

The current pandemic of Coronavirus Disease 2019 (COVID-19) raised several concerns about using conventional textiles for manufacturing personal protective equipment without self-disinfecting properties since the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is transmitted mainly by aerosols that can transpose cotton masks. Therefore, developing new cotton fibers with high self-disinfecting ability is essential to avoid a new pandemic due to new SARS-CoV-2 variants. Herein, we developed cotton wipes (CFs) with fibers coated by Ag, TiO2, and Ag/TiO2 hybrid nanoparticles like Brazilian heavy-fruited Myrciaria cauliflora by a sonochemical approach. Moreover, the coated CFs present high antimicrobial performance against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), being able to inactivate infectious SARS-CoV-2 (Delta variant) by the destruction of the spike, membrane, and nucleocapsid proteins while the viral RNA is not significantly affected, according to the molecular biological findings.

Questioning ZnO, Ag, and Ag/ZnO nanoparticles as antimicrobial agents for textiles: Do they guarantee total protection against bacteria and SARS-CoV-2?

Coronavirus Disease 2019 (COVID-19) occasioned global economic and health systems collapse. Also, it raised several concerns about using conventional cotton fabrics for manufacturing personal protective equipment without the antimicrobial capacity to inactivate viruses, such as Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and its variants. Therefore, developing antimicrobial cotton fibers is crucial to avoid new global pandemics or the transmission of dangerous pathogens that remain on surfaces for long periods, especially in hospitals and medical clinics. Herein, we developed antimicrobial cotton fabrics with Ag, ZnO, and Ag/ZnO nanoparticles and evaluated their bactericidal activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), photocatalytic activity, and antiviral activity against Delta SARS-CoV-2. Although the antimicrobial fabrics are effective against these bacteria, they only reduce part of the SARS-CoV-2 virions during the first 15 min of direct contact via damage only to biological structures on the viral surface particle while the viral RNA remains intact.

Cotton Fabrics Decorated with Antimicrobial Ag-Coated TiO2 Nanoparticles Are Unable to Fully and Rapidly Eradicate SARS-CoV-2.

The successful development of multifunctional cotton fabrics with antimicrobial and antiviral activities is essential to prevent the proliferation of microorganisms and transmission of coronavirus virions today, especially with the emergence of new variants of SARS-CoV-2. In this work, we developed antimicrobial cotton fabrics with Ag/TiO2 nanoparticles synthesized via sonochemistry. Here, we show that more than 50% of infectious SARS-CoV-2 remain active after prolonged direct contact self-disinfecting materials capable of inhibiting the proliferation of Escherichia coli and Staphylococcus aureus. The findings bring several epidemiologic worries about using silver and TiO2 as self-disinfecting nanostructured agents to prevent coronavirus transmission.

Dengue-2 and Guadeloupe Mosquito Virus RNA Detected in Aedes (Stegomyia) spp. Collected in a Vehicle Impound Yard in Santo André, SP, Brazil.

In 2018-2019, we conducted mosquito collections in a municipal vehicle impound yard, which is 10 km from the Serra do Mar Environmental Protection Area in Santo André, SP, Brazil. Our aim is to study arboviruses in the impound yard, to understand the transmission of arboviruses in an urban environment in Brazil. We captured the mosquitoes using human-landing catches and processed them for arbovirus detection by conventional and quantitative RT-PCR assays. We captured two mosquito species, Aedes aegypti (73 total specimens; 18 females and 55 males) and Ae. albopictus (34 specimens; 27 females and 7 males). The minimum infection rate for DENV-2 was 11.5 per 1000 (CI95%: 1-33.9). The detection of DENV-2 RNA in an Ae. albopictus female suggests that this virus might occur in high infection rates in the sampled mosquito population and is endemic in the urban areas of Santo André. In addition, Guadeloupe mosquito virus RNA was detected in an Ae. aegypti female. To our knowledge, this was the first detection of the Guadeloupe mosquito virus in Brazil.

High-resolution structure of a modular hyperthermostable endo-ß-1,4-mannanase from Thermotoga petrophila: The ancillary immunoglobulin-like module is a thermostabilizing domain.

The endo-ß-1,4-mannanase from the hyperthermostable bacterium Thermotoga petrophila (TpMan) is an enzyme that catalyzes the hydrolysis of mannan and heteromannan polysaccharides. Of the three domains that comprise TpMan, the N-terminal GH5 catalytic domain and the C-terminal carbohydrate-binding domain are connected through a central ancillary domain of unknown structure and function. In this study, we report the partial crystal structure of the TpMan at 1.45 Å resolution, so far, the first modular hyperthermostable endo-ß-1,4-mannanase structure determined. The structure exhibits two domains, a (ß/α)8-barrel GH5 catalytic domain connected via a linker to the central domain with an immunoglobulin-like ß-sandwich fold formed of seven ß-strands. Functional analysis showed that whereas the immunoglobulin-like domain does not have the carbohydrate-binding function, it stacks on the GH5 catalytic domain acting as a thermostabilizing domain and allowing operation at hyperthermophilic conditions. The carbohydrate-binding domain is absent in the crystal structure most likely due to its high flexibility around the immunoglobulin-like domain which may act also as a pivot. These results represent new structural and functional information useful on biotechnological applications for biofuel and food industries.

Conformational changes in a hyperthermostable glycoside hydrolase: enzymatic activity is a consequence of the loop dynamics and protonation balance.

Endo-ß-1, 4-mannanase from Thermotoga petrophila (TpMan) is a modular hyperthermostable enzyme involved in the degradation of mannan-containing polysaccharides. The degradation of these polysaccharides represents a key step for several industrial applications. Here, as part of a continuing investigation of TpMan, the region corresponding to the GH5 domain (TpManGH5) was characterized as a function of pH and temperature. The results indicated that the enzymatic activity of the TpManGH5 is pH-dependent, with its optimum activity occurring at pH 6. At pH 8, the studies demonstrated that TpManGH5 is a molecule with a nearly spherical tightly packed core displaying negligible flexibility in solution, and with size and shape very similar to crystal structure. However, TpManGH5 experiences an increase in radius of gyration in acidic conditions suggesting expansion of the molecule. Furthermore, at acidic pH values, TpManGH5 showed a less globular shape, probably due to a loop region slightly more expanded and flexible in solution (residues Y88 to A105). In addition, molecular dynamics simulations indicated that conformational changes caused by pH variation did not change the core of the TpManGH5, which means that only the above mentioned loop region presents high degree of fluctuations. The results also suggested that conformational changes of the loop region may facilitate polysaccharide and enzyme interaction. Finally, at pH 6 the results indicated that TpManGH5 is slightly more flexible at 65°C when compared to the same enzyme at 20°C. The biophysical characterization presented here is well correlated with the enzymatic activity and provide new insight into the structural basis for the temperature and pH-dependent activity of the TpManGH5. Also, the data suggest a loop region that provides a starting point for a rational design of biotechnological desired features.

Fatal systemic toxoplasmosis in Valley quail (Callipepla californica).

An adult, captive raised male Valley quail (Callipepla californica) acquired by a southern Brazilian aviary suddenly showed severe apathy, dyspnea and diarrhea, and died 18 hours after the onset of illness. At necropsy, pale muscles and whitish areas in the heart, splenomegaly, hepatomegaly, and consolidated red lungs were observed. Histological findings were mainly mononuclear inflammation with necrosis of liver, heart, spleen, bone marrow and lung. There were large numbers of Toxoplasma gondii tachyzoitesorganisms in the liver, heart, spleen, bone marrow, lungs, trachea, kidneys, adrenal glands, testes, intestines, and pancreas. These organisms were seen free in the organs' stroma or within macrophages and stained positively with polyclonal antiserum to T. gondii. Genomic DNA was extracted from the tissues and PCR was used to target the B1 gene of T. gondii. The genotypic characterization by PCR-RFLP with 11 markers (SAG1, SAG2 and alt. SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, Apico and CS3) revealed the ToxoDB-PCR-RFLP #87 genotype, the same as previously identified in a backyard chicken (TgCkBr156) in Rio Grande do Sul, Brazil.

Occurrence of antibodies against Toxoplasma gondii and its isolation and genotyping in donkeys, mules, and horses in Brazil.

The occurrence of antibodies against Toxoplasma gondii was determined in donkeys, mules, and horses from different regions of Brazil. Serum samples from 304 donkeys (67.11%), 118 horses (26.05%), and 31 mules (6.84%) were analyzed by means of the indirect fluorescent antibody test (cutoff=64). Antibodies against T. gondii were detected in 129 equids (28.47%) (82 donkeys, 32 horses, and 15 mules). Tissue samples from 19 seropositive and 50 seronegative animals were obtained in order to isolate the parasite by means of mouse bioassay, and T. gondii was isolated from a donkey. Through genotypic characterization of the isolate, by means of polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) using 11 genotypic markers, the genotype #163 (TgCkBr220), which has already been described in chickens in Brazil, was identified.

Seroepidemiology of Toxoplasma gondii infection in bats from São Paulo city, Brazil.

Toxoplasmosis is a parasitic zoonosis caused by Toxoplasma gondii protozoan with a worldwide distribution. The aim of this study was to determine the frequency of IgG anti-T. gondii antibodies in bats from São Paulo city, Brazil. A total of 616 serum samples were collected from 22 species of bats. Anti-T. gondii antibodies were searched using the indirect fluorescent antibody test (IFAT ≥ 1:16) and IgG anti-bat antibodies produced in sheep on samples collected during 2006-2011; 32.62% (201/616) of bats had T. gondii antibodies. The modified agglutination test (MAT ≥ 1:25) was performed on samples collected during 2010-2011; 18.61% (35/188) were seropositive. The concordance between IFAT and MAT (serum samples from 2010 to 2011) by Kappa (95% CI) was 0.144, resulting in a low agreement between the techniques. The specificity and sensitivity of MAT and IFAT have not been evaluated for the diagnosis of toxoplasmosis in bats. Thus, it was verified that bats are exposed to T. gondii during their lifetime and they are also part of the toxoplasmosis epidemiology.