In vivo immunostimulatory effect of the amoebocyte lysate and plasma of Asian horseshoe crab, Tachypleus gigas in a piscine model.

Antimicrobial proteins/peptides are becoming a new generation of immunostimulants for prevention and disease control in human and animals, including aquatic animals. As the haemolymph of horseshoe crabs (Tachypleus) contains broad ranges of bioactive compounds, we have explored the in vivo immunostimulating potential of amoebocyte lysate and plasma using a fish model. Indian major carp, Labeo rohita, yearlings were injected intraperitoneally with two doses of lysate and plasma at 50 and 100 µg protein per fish. No abnormalities and/or mortalities were recorded in any group. L. rohita injected with 50 µg lysate and 100 µg plasma protein showed significant enhancement (P < 0.01) of various haematological and immunological parameters. There was a significant rise in the total protein and globulin content, myeloperoxidase and respiratory burst activity following injection with 50 µg lysate and 100 µg plasma protein. The agglutinating and haemagglutinating activities were increased albeit not significantly (P > 0.01) in any groups. On the contrary, a significantly high hemolysin titre was recorded in fish that received 100 µg plasma protein. Following challenge with Aeromonas hydrophila, both lysate and plasma protein(s) cross protected the fish after 30 days. The highest survival (50%) was recorded in group injected with 50 µg lysate protein, followed by 45% in both 100 µg lysate and plasma protein injected groups.

Harmonized One Health Trans-Species and Community Surveillance for Tackling Antibacterial Resistance in India: Protocol for a Mixed Methods Study.

BACKGROUND: India has the largest burden of drug­resistant organisms compared with other countries around the world, including multiresistant and extremely drug­resistant tuberculosis and resistant Gram­negative and Gram­positive bacteria. Antibiotic resistant bacteria are found in all living hosts and in the environment and move between hosts and ecosystems. An intricate interplay of infections, exposure to antibiotics, and disinfectants at individual and community levels among humans, animals, birds, and fishes triggers evolution and spread of resistance. The One Health framework proposes addressing antibiotic resistance as a complex multidisciplinary problem. However, the evidence base in the Indian context is limited. OBJECTIVE: This multisectoral, trans-species surveillance project aims to document the infection and resistance patterns of 7 resistant-priority bacteria and the risk factors for resistance following the One Health framework and geospatial epidemiology. METHODS: This hospital- and community-based surveillance adopts a cross-sectional design with mixed methodology (quantitative, qualitative, and spatial) data collection. This study is being conducted at 6 microbiology laboratories and communities in Khurda district, Odisha, India. The laboratory surveillance collects data on bacteria isolates from different hosts and their resistance patterns. The hosts for infection surveillance include humans, animals (livestock, food chain, and pet animals), birds (poultry), and freshwater fishes (not crustaceans). For eligible patients, animals, birds and fishes, detailed data from their households or farms on health care seeking (for animals, birds and fishes, the illness, and care seeking of the caretakers), antibiotic use, disinfection practices, and neighborhood exposure to infection risks will be collected. Antibiotic prescription and use patterns at hospitals and clinics, and therapeutic and nontherapeutic antibiotic and disinfectant use in farms will also be collected. Interviews with key informants from animal breeding, agriculture, and food processing will explore the perceptions, attitudes, and practices related to antibiotic use. The data analysis will follow quantitative (descriptive and analytical), qualitative, and geospatial epidemiology principles. RESULTS: The study was funded in May 2019 and approved by Institute Ethics Committees in March 2019. The data collection started in September 2019 and shall continue till March 2021. As of June 2020, data for 56 humans, 30 animals and birds, and fishes from 10 ponds have been collected. Data analysis is yet to be done. CONCLUSIONS: This study will inform about the bacterial infection and resistance epidemiology among different hosts, the risk factors for infection, and resistance transmission. In addition, it will identify the potential triggers and levers for further exploration and action. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/23241.

Alginate-chitosan-PLGA composite microspheres induce both innate and adaptive immune response through parenteral immunization in fish.

Alginate-chitosan-PLGA composite microspheres encapsulating outer membrane protein antigen of Aeromonas hydrophila as an antigen carrier was explored for the first time in a fish model. This composite microsphere showed distinct advantages over the conventional PLGA microparticles in aspects of the high encapsulation efficiency due to the protein-friendly microenvironment created by the hydrophilic alginate-chitosan cores of the composite microspheres, preventing initial burst release and the elimination of lyophilizing process. The antibody responses significantly increased and persist up to 9 weeks in composite microspheres unlike that PLGA microsphere, native OMP and FIA adjuvant. Moreover, several innate immune parameters as respiratory burst, lysozyme and complement activity were significantly increased in both composite and PLGA microspheres up to 9 weeks than other treated groups. It also gives protection from A. hydrophila infection and brought some hope, for its application in replacement with conventional PLGA microparticle for antigen delivery in fish.

Antigen adsorbed surface modified poly-ɛ-caprolactone microspheres stimulates both adaptive and innate immune response in fish.

Surface modified poly-ɛ-caprolactone microspheres as an antigen carrier was explored in a fish model. Outer membrane vesicles of Edwardsiella tarda adsorbed on to surface modified poly-ɛ-caprolactone microspheres with chitosan and alginate induces both innate and adaptive immune responses which persist up to 63 days of post immunization through parenteral immunization unlike that of free and FIA adjuvented antigens. These results highlight the role of these microspheres as an adjuvant/antigen carrier in fish.

Antigen adsorbed calcium phosphate nanoparticles stimulate both innate and adaptive immune response in fish, Labeo rohita H.

Calcium phosphate nanoparticles as an antigen/protein delivery was explored in a fish model Labeo rohita H. S-layer protein (of Aeromonas hydrophila) adsorbed on nano sized calcium phosphate particles elicited both innate and adaptive immune parameters which persisted up to 63 days of post immunization through parenteral immunization and gave cross protections.