Autoimmune diseases are caused when immune cells act against self-protein. This biological self–non-self-discrimination phenomenon is controlled by a distinct group of lymphocytes known as regulatory T cells (Tregs), which are key inflammatory response regulators and play a pivotal role in immune tolerance and homeostasis. Treg-mediated robust immunosuppression provides self-tolerance and protection against autoimmune diseases. However, once this system fails to operate or poorly operate, it leads to an extreme situation where immune system reacts against self-antigens and destroys host organs, thus causing autoimmune diseases. Tregs can target both innate and adaptive immunity via modulating multiple immune cells such as neutrophils, monocytes, antigen-presenting cells, B cells, and T cells. This review highlights the Treg-mediated immunosuppression, role of several markers and their interplay during Treg development and differentiation, and advances in therapeutic aspects of Treg cells to reduce severity of autoimmunity-related conditions along with emphasizing limitations and challenges of their usages.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a severe pandemic of the current century. The vicious tentacles of the disease have been disseminated worldwide with unknown complications and repercussions. Advanced COVID-19 syndrome is characterized by the uncontrolled and elevated release of pro-inflammatory cytokines and suppressed immunity, leading to the cytokine storm. The uncontrolled and dysregulated secretion of inflammatory and pro-inflammatory cytokines is positively associated with the severity of the viral infection and mortality rate. The secretion of various pro-inflammatory cytokines such as TNF-α, IL-1, and IL-6 leads to a hyperinflammatory response by recruiting macrophages, T and B cells in the lung alveolar cells. Moreover, it has been hypothesized that immune cells such as macrophages recruit inflammatory monocytes in the alveolar cells and allow the production of large amounts of cytokines in the alveoli, leading to a hyperinflammatory response in severely ill patients with COVID-19. This cascade of events may lead to multiple organ failure, acute respiratory distress, or pneumonia. Although the disease has a higher survival rate than other chronic diseases, the incidence of complications in the geriatric population are considerably high, with more systemic complications. This review sheds light on the pivotal roles played by various inflammatory markers in COVID-19-related complications. Different molecular pathways, such as the activation of JAK and JAK/STAT signaling are crucial in the progression of cytokine storm; hence, various mechanisms, immunological pathways, and functions of cytokines and other inflammatory markers have been discussed. A thorough understanding of cytokines’ molecular pathways and their activation procedures will add more insight into understanding immunopathology and designing appropriate drugs, therapies, and control measures to counter COVID-19. Recently, anti-inflammatory drugs and several antiviral drugs have been reported as effective therapeutic drug candidates to control hypercytokinemia or cytokine storm. Hence, the present review also discussed prospective anti-inflammatory and relevant immunomodulatory drugs currently in various trial phases and their possible implications.

Real-time RT-PCR is considered the gold standard confirmatory test for coronavirus disease 2019 (COVID-19). However, many scientists disagree, and it is essential to understand that several factors and variables can cause a false-negative test. In this context, cycle threshold (Ct) values are being utilized to diagnose or predict SARS-CoV-2 infection. This practice has a significant clinical utility as Ct values can be correlated with the viral load. In addition, Ct values have a strong correlation with multiple haematological and biochemical markers. However, it is essential to consider that Ct values might be affected by pre-analytic, analytic, and post-analytical variables such as collection technique, specimen type, sampling time, viral kinetics, transport and storage conditions, nucleic acid extraction, viral RNA load, primer designing, real-time PCR efficiency, and Ct value determination method. Therefore, understanding the interpretation of Ct values and other influential factors could play a crucial role in interpreting viral load and disease severity. In several clinical studies consisting of small or large sample sizes, several discrepancies exist regarding a significant positive correlation between the Ct value and disease severity in COVID-19. In this context, a revised review of the literature has been conducted to fill the knowledge gaps regarding the correlations between Ct values and severity/fatality rates of patients with COVID-19. Various databases such as PubMed, Science Direct, Medline, Scopus, and Google Scholar were searched up to April 2021 by using keywords including “RT-PCR or viral load”, “SARS-CoV-2 and RT-PCR”, “Ct value and viral load”, “Ct value or COVID-19”. Research articles were extracted and selected independently by the authors and included in the present review based on their relevance to the study. The current narrative review explores the correlation of Ct values with mortality, disease progression, severity, and infectivity. We also discuss the factors that can affect these values, such as collection technique, type of swab, sampling method, etc.

Fish and aquatic-derived zoonotic diseases have caused considerable problems in the aquaculture industry and fisheryworldwide. In particular, zoonotic diseases can pose widespread threats to humans. With the world's growing population and potential global trade of aquaculture and fish, the risk of environmental contamination and development of fish and aquatic-derived zoonoses in humans are increasing. The important causes of zoonoses include bacteria, parasites, viruses, and fungi. The zoonotic bacterial agents are divided into two main groups: Gram-positive (Mycobacteriaceae, Streptococcaceae, Erysipelothricaceaefamilies) and Gram-negative (Aeromonadaceae, Vibrionaceae, Pseudomondaceae,Enterobacteriaceae,and Hafniaceaefamilies). The premier parasitic agents include cestodes (tapeworm; e.g.,Diphyllobothrium spp.), trematodes (fluke; e.g., Opisthorchis spp.), and nematodes (round worm;e.g., Anisakis spp.). In addition, protozoan organisms such as Cryptosporidium spp. are also considered fish-derivedzoonotic pathogens.Two groups of fish-associated fungi causing basidiobolomycosis and sporotrichosisalso pose a zoonotic risk for humans. The majority of the fish-derived zoonotic diseases are transmitted to humansmainly via the consumption of improperly cooked or raw fish or fish products. Therefore, the incidence of zoonotic diseases can be reduced by properly processing fish and fish products, e.g., by thermal (heat/freezing) treatment. The prevalence of zoonotic agents in fishes varies seasonally and should be regularly monitored to evaluate the prevalence of pathogens in both wild and cultured fish populations. This reviewfocuses on the fish zoonotic agents/diseases and their control and prevention.

The field of nanotechnology has revolutionised global attempts to prevent, treat, and eradicate infectious diseases in the foreseen future. Nanovaccines have proven to be a valuable pawn in this novel technology. Nanovaccines are made up of nanoparticles that are associated with or prepared with components that can stimulate the host's immune system. In addition to their delivery capabilities, the nanocarriers have been demonstrated to possess intrinsic adjuvant properties, working as immune cell stimulators. Thus, nanovaccines have the potential to promote rapid as well as long-lasting humoral and cellular immunity. The nanovaccines have several possible benefits, including site-specific antigen delivery, increased antigen bioavailability, and a diminished adverse effect profile. To avail these benefits, several nanoparticle-based vaccines are being developed, including virus-like particles, liposomes, polymeric nanoparticles, nanogels, lipid nanoparticles, emulsion vaccines, exomes, and inorganic nanoparticles. Inspired by their distinctive properties, researchers are working on the development of nanovaccines for a variety of applications, such as cancer immunotherapy and infectious diseases. Although a few challenges still need to be overcome, such as modulation of the nanoparticle pharmacokinetics to avoid rapid elimination from the bloodstream by the reticuloendothelial system, The future prospects of this technology are also assuring, with multiple options such as personalised vaccines, needle-free formulations, and combination nanovaccines with several promising candidates.

Salinity stress is a major constrain in the global rice production and hence serious efforts are being undertaken towards deciphering its remedial strategies. The comparative analysis of differential response of salt sensitive and salt tolerant lines is a judicious approach to obtain essential clues towards understanding the acquisition of salinity tolerance in rice plants. However, adaptation to salt stress is a fairly complex process and operates through different mechanisms. Among various mechanisms involved, the reactive oxygen species mediated salinity tolerance is believed to be critical as it evokes cascade of responses related to stress tolerance. In this background, the present paper for the first time evaluates the ROS generating and the scavenging system in tandem in both salt sensitive and salt tolerant cultivars of rice for getting better insight into salinity stress adaptation. Comparative analysis of ROS indicates the higher level of hydrogen peroxide (H2O2) and lower level of superoxide ions (O2-) in the salt tolerant as compared to salt sensitive cultivars. Specific activity of ROS generating enzyme, NADPH oxidase was also found to be more in the tolerant cultivars. Further, activities of various enzymes involved in enzymatic and non enzymatic antioxidant defence system were mostly higher in tolerant cultivars. The transcript level analysis of antioxidant enzymes were in alignment with the enzymatic activity. Other stress markers like proline were observed to be higher in tolerant varieties whereas, the level of malondialdehyde (MDA) equivalents and chlorophyll content were estimated to be more in sensitive. The present study showed significant differences in the level of ROS production and antioxidant enzymes activities among sensitive and tolerant cultivars, suggesting their possible role in providing natural salt tolerance to selected cultivars of rice. Our study demonstrates that the cellular machinery for ROS production and scavenging system works in an interdependent manner to offer better salt stress adaptation in rice. The present work further highlights that the elevated level of H2O2 which is considered as a key determinant for conferring salt stress tolerance to rice might have originated through an alternative route of photocatalytic activity of chlorophyll.