Emerging and re-emerging viral infections in India

The Past, Present, and Future of One Health in India: A Narrative Review

Humans have experienced a long-lasting pandemic of COVID-19 going on since the year 2020. Such events have recently increased the demand for a competent disease outbreak response system, more precisely, a One Health platform. The interaction between humans, animals, and ecosystems is inevitable. It is a known fact that the interface between these three entities is important for survival. In rural areas, especially in developing countries, it is a common practice to keep the animal shed in close proximity to their homes. Further, this intricate relationship itself plays a role in the spread and transmission of the disease. The involvement of the human-animal interface in emerging and re-emerging diseases has caused havoc in recent times and might prove challenging to overcome. Over the years, many efforts have been made on international and national platforms to adopt and implement a transdisciplinary, collaborative, intersectoral approach in India. This review highlights the major initiatives taken for the implementation of one health and the challenges faced over the years in our country.

Immunization against arthropod protein impairs transmission of rickettsial pathogen from ticks to the vertebrate host

Human anaplasmosis caused by Anaplasma phagocytophilum is one of the most common tick-borne diseases in the United States. The black-legged ticks, Ixodes scapularis, vector and transmit this bacterium to humans. In this study, we provide evidence that targeting I. scapularis membrane-bound organic anion transporting polypeptide 4056 (IsOATP4056) with an anti-vector vaccine affects transmission of A. phagocytophilum from ticks to the vertebrate host. Anaplasma phagocytophilum induces expression of IsOATP4056 in ticks and tick cells. Increased membrane localization of IsOATP4056 was evident in A. phagocytophilum-infected tick cells. Treatment with high dose (10 µg/ml) but not low dose (5 µg/ml) of EL-6 antibody that targets the largest extracellular loop of IsOATP4056 showed cytotoxic effects in tick cells but not in human keratinocyte cell line (HaCaT). Passive immunization, tick-mediated transmission and in vitro studies performed with mice ordered from two commercial vendors and with tick cells showed that EL-6 antibody not only impairs A. phagocytophilum transmission from ticks to the murine host but also aids in the reduction in the bacterial loads within engorged ticks and in tick cells by activation of arthropod Toll pathway. Furthermore, reduced molting efficiency was noted in ticks fed on EL-6 antibody-immunized mice. Collectively, these results provide a good candidate for the development of anti-tick vaccine to target the transmission of A. phagocytophilum and perhaps other tick-borne pathogens of medical importance.