Photodynamic therapy for ESKAPE pathogens: An emerging approach to combat antimicrobial resistance (AMR).

The increase in antimicrobial resistance, particularly in ESKAPE pathogens, has resulted in the dire need for new therapeutic approaches. ESKAPE is an acronym for a group of bacteria that are responsible for a majority of nosocomial and community acquired infections. The acronym stands for Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species. These pathogens are known for their ability to develop resistance to multiple antibiotics, making them difficult to treat thus posing a significant threat to public health. In light of the alarming consequences of antimicrobial resistance, it has been estimated that, in the absence of a substantial increase in the rate of development of new effective drugs, the number of casualties related to these infections will increase from about 700,000 in 2016 up to nearly 10,000,000 in 2050 [1]. One potential strategy to treat these pathogens is photodynamic therapy (PDT). In the early 20th century, Oscar Raab observed the phototoxicity of acridine red against Paramecium caudatum, while Tappenier and Jesionek demonstrated the photodynamic effects of eosin for treating cutaneous diseases. These discoveries laid the foundation for Photodynamic Therapy (PDT), which utilizes a non-toxic photosensitizer (PS) followed by targeted light irradiation for treatment [2]. PDT involves the use of a photosensitizer, a light source, and oxygen to eliminate highly active infectious pathogens such as bacteria, viruses, and fungi. PDT is known to possess several advantages including localized treatment and fewer side effects. Various photosensitizers and light sources have been assessed in different strains, showing promising results suggesting PDT to be a promising potential treatment option. PDT utilizes PS compounds with suitable light absorption that showcase effective results against the pathogens in vitro and in vivo, including BODIPY derivatives, Methylene Blue, and other dyes like porphyrin derivatives, phthalocyanines, indole derivatives, Photophrin, etc., inhibiting the growth of infections, for both in planktonic cells and in biofilms. Combination of PDT with other therapies like efflux pump inhibitors or quorum sensing inhibitors has also proven to be efficacious. However, this domain further needs to be assessed before it reaches the society.

Perceiving biobased plastics as an alternative and innovative solution to combat plastic pollution for a circular economy.

Plastic waste from fossil-based sources, including single-use packaging materials, is continuously accumulating in landfills, and leaching into the environment. A 2021 UN Environment Programme (UNEP) report suggests that the plastic pollution is likely to be doubled by 2030, posing a major challenge to the environment and the overall global plastic waste management efforts. The use of biobased plastics such as polyhydroxyalkanoates (PHAs) as a biodegradable substitute for petroleum-based plastics could be a feasible option to combat this issue which may further result in much lower carbon emissions and energy usage in comparison to conventional plastics as additional advantages. Though recent years have seen the use of microbes as biosynthetic machinery for biobased plastics, using various renewable feedstocks, the scaled-up production of such materials is still challenging. The current study outlays applications of biobased plastics, potential microorganisms producing biobased plastics such as Cupriavidus necator, Bacillus sp., Rhodopseudomonas palustris, microalgae, and mixed microbial cultures, and inexpensive and renewable resources as carbon substrates including industrial wastes. This review also provides deep insights into the operational parameters, challenges and mitigation, and future opportunities for maximizing the production of biobased plastic products. Finally, this review emphasizes the concept of biorefinery as a sustainable and innovative solution for biobased plastic production for achieving a circular bioeconomy.

Successful application of wastewater-based epidemiology in prediction and monitoring of the second wave of COVID-19 with fragmented sewerage systems-a case study of Jaipur (India).

The present study tracked the city-wide dynamics of severe acute respiratory syndrome-corona virus 2 ribonucleic acids (SARS-CoV-2 RNA) in the wastewater from nine different wastewater treatment plants (WWTPs) in Jaipur during the second wave of COVID-19 out-break in India. A total of 164 samples were collected weekly between February 19th and June 8th, 2021. SARS-CoV-2 was detected in 47.2% (52/110) influent samples and 37% (20/54) effluent samples. The increasing percentage of positive influent samples correlated with the city's increasing active clinical cases during the second wave of COVID-19 in Jaipur. Furthermore, wastewater-based epidemiology (WBE) evidence clearly showed early detection of about 20 days (9/9 samples reported positive on April 20th, 2021) before the maximum cases and maximum deaths reported in the city on May 8th, 2021. The present study further observed the presence of SARS-CoV-2 RNA in treated effluents at the time window of maximum active cases in the city even after tertiary disinfection treatments of ultraviolet (UV) and chlorine (Cl2) disinfection. The average genome concentration in the effluents and removal efficacy of six commonly used treatments, activated sludge process + chlorine disinfection (ASP + Cl2), moving bed biofilm reactor (MBBR) with ultraviolet radiations disinfection (MBBR + UV), MBBR + chlorine (Cl2), sequencing batch reactor (SBR), and SBR + Cl2, were compared with removal efficacy of SBR + Cl2 (81.2%) > MBBR + UV (68.8%) > SBR (57.1%) > ASP (50%) > MBBR + Cl2 (36.4%). The study observed the trends and prevalence of four genes (E, RdRp, N, and ORF1ab gene) based on two different kits and found that prevalence of N > ORF1ab > RdRp > E gene suggested that the effective genome concentration should be calculated based on the presence/absence of multiple genes. Hence, it is imperative to say that using a combination of different detection genes (E, N, RdRp, & ORF1ab genes) increases the sensitivity in WBE.

Antigenicity of a Bacterially Expressed Triple Chimeric Antigen of Plasmodium falciparum AARP, MSP-311 and MSP-119: PfAMSP-Fu35.

Development of fusion chimeras as potential vaccine candidates is considered as an attractive strategy to generate effective immune responses to more than one antigen using a single construct. Here, we described the design, production, purification and antigenicity of a fusion chimera (PfAMSP-Fu35), comprised of immunologically relevant regions of three vaccine target malaria antigens, PfAARP, PfMSP-3 and PfMSP-1. The recombinant PfAMSP-Fu35 is expressed as a soluble protein and purified to homogeneity with ease at a yield of ~ 7 mg L-1. Conformational integrity of the C-terminal fragment of PfMSP-1, PfMSP-119 was retained in the fusion chimera as shown by ELISA with conformation sensitive monoclonal antibodies. High titre antibodies were raised to the fusion protein and to all the three individual components in mice and rabbits upon immunization with fusion chimera in two different adjuvant formulations. The sera against PfAMSP-Fu35 recognized native parasite proteins corresponding to the three components of the fusion chimera. As shown by invasion inhibition assay and antibody mediated cellular inhibition assay, antibodies purified from the PfAMSP-Fu35 immunized serum successfully and efficiently inhibited parasite invasion in P. falciparum 3D7 in vitro both directly and in monocyte dependent manner. However, the invasion inhibitory activity of anti-AMSP-Fu35 antibody is not significantly enhanced as expected as compared to a previously described two component fusion chimera, MSP-Fu24. Therefore, it may not be of much merit to consider AMSP-Fu35 as a vaccine candidate for preclinical development.

Characterization of fine specificity of the immune response to a Plasmodium falciparum rhoptry neck protein, PfAARP.

BACKGROUND: Immunological characterization of potential blood-stage malaria antigens would be a valuable strategy in the development of an effective vaccine. Identifying B and CD4(+) T cell epitopes will be important in understanding the nature of immune response. A previous study has shown that Plasmodium falciparum apical asparagine-rich protein (PfAARP) stimulates immune response and induces potent invasion-inhibitory antibodies. Antibodies to PfAARP provide synergistic effects in inhibition of parasite invasion when used in combination with antibodies to other antigens. In the present study, an attempt was made to identify B cell and CD4(+) T cell epitopes of PfAARP. METHODS: Balb/c mice were immunized with recombinant PfAARP and both cellular and humoral responses were analysed at various time points. Computerized databases [immune epitope database (IEDB) and B cell epitope prediction (BCEPred)] were used to predict epitope sequences within PfAARP and predicted peptides were synthesized. In addition, nine 18 amino acid, long-overlapping peptides spanning the entire length of PfAARP were synthesized. Using these peptides, B cell and CD4(+) T cell responses in PfAARP immunized mice were measured by ELISA and ELISPOT assays. RESULTS: Here, it is demonstrated that immunization of mice with PfAARP induced long-lasting, high-titre antibodies (4 months post immunization). Also, the recombinant protein was effective in inducing a pronounced Th1 type of immune response quantified by IFN-γ ELISA and ELISPOT. It was found that the predicted peptides did not represent the immunogenic regions of PfAARP. However, of the nine overlapping peptides, three peptides (peptides 3, 5 and 7) were strongly recognized by PfAARP-immunized sera and represented B cell epitopes. Also, peptide 3 elicited IFN- γ response, suggesting it to be a T-cell epitope. CONCLUSIONS: Induction of long-lasting humoral and cellular response on PfAARP immunization in mice underscores its possible use as a blood-stage malaria vaccine candidate. Mapping of immunogenic regions may help in designing fusion chimera containing immunologically relevant regions of other vaccine target antigens and/or for multi-component vaccine candidates.