neutralizing antibodies

Introduction - evolution of SARS-CoV-2 variants: With the unrestrained pandemic for over last one-and-half year, SARS-CoV-2 seems to have adapted to its habitat, the human host, through mutations that facilitate its replication and transmission. The G variant incorporating D614G mutation, potently more transmissible than the ancestral virus arose during January 2020 and spread widely. Since then, various SARS-CoV-2 variants of concern (VOCs) and variants of interest (VOIs) with higher infectivity or virulence or both, have evolved on the background of G variant, and spread widely. SARS-CoV-2 infection and the immunodynamics: As the virus becomes more transmissible, its lethality may drop. Apart from the humoral immunity, T-cell recognition from a previous SARS-CoV-2 infection or vaccination may modify the disease transmission correlates and its clinical manifestations. On the other hand, the immunity generated may reduce probability of re-infection as well as limit evolution of adaptive mutations, and emergence of highly infectious and immune-escape variants. There are complex issues related to the SARS-CoV-2 evolutionary dynamics and host’s immunodynamics. Trending etiopathoimmunological correlates: The evolution potential of SARS-CoV-2 is limited because of proofreading function of nsp14. The S protein mutations affect transmissibility, virulence, and vaccine efficacy. The D614G mutation in G variant with higher infectivity has turned the Chinese epidemic into a pandemic. Other SARS-CoV-2 variants, such as Alpha, Beta, Gamma, and Delta seem to have evolved as result of adaptation to selective pressures during periods of prolonged infections and subsequent transmission. Further, there is issue of convergent association of mutations. Basics of immunity and immune system failure: The nature of the immune response after natural SARS-CoV-2 infection is variable and diverse. There are pre-existing neutralizing antibodies and sensitized T cells elicited during previous infection with seasonal CoVs influencing the disease susceptibility and course. The virus has evolved adaptive mechanisms to reduce its exposure to IFN-I and there are issues related to erratic and overactive immune response. The altered neutralizing epitopes in the S protein in SARS-CoV-2 variants modify the immune landscapes and clinical manifestations. Conclusion: current scenarios and prospects: Presently, the SARS-CoV-2 infection is widespread with multiple evolving infectious variants. There is probability of its transition from epidemic to endemic phase in due course manifesting as a mild disease especially in the younger population. Conversely, the pandemic may continue with enhanced disease severity due to evolving variants, expanded infection pool, and changing immunity landscape. There is need to plan for the transition and continued circulation of the virus during the endemic phase or continuing pandemic for indefinite period.

The COVID-19 pandemic appeared in late 2019 and became a major health concern with rapid transmission and very high mortality rates across the globe. Although precautionary, preventive, protective and therapeutic measures have been adopted against COVID-19, still the disease has drastically affected people. In order to overcome the challenges of the pandemic, the understanding of the route of transmission, its fusion with receptors and invasion into the human body and hacking the immune system, the viral genome was sequenced. The viral genome keeps on mutating and altering its original form into its subtypes. Moreover, age and comorbid conditions had their impact on developing the disease differing from individual to individual due to interaction varying between the host genome and virus. Considering the pathogenesis of the virus, neutralizing antibodies reduced the viral impact and severity. This review is focused on highlighting the COVID-19 genome, host genetic factors, the pathogenesis of the disease and available therapeutic measures to overcome the pandemic.

Porcine Epidemic Diarrhea Virus (PEDV) can infect pigs of any age, but the disease severity varies significantly, particularly affecting neonatal piglets due to their immature immune system. Various vaccination strategies have been questioned for their efficacy, especially since outbreaks have occurred even on vaccinated farms. Recent suggestions indicate that exposure to the virus may enhance the effectiveness of inactivated vaccines, highlighting the potential benefits of using attenuated viruses to generate immunity in sows without prior exposure. This study aimed to evaluate the humoral and cytokine responses in pregnant sows and their piglets after inoculation of affected piglet intestinal contents and a virus isolated. We measured immune parameters such as IL-12, IL-22, IgG, and IgA, as well as neutralizing antibodies in serum, colostrum, and milk. Notably, higher titers of neutralizing antibodies were found in sows immunized with the viral inoculum, while IL-12 and IL-22 levels showed no significant differences. Additionally, we assessed productive parameters like total piglets born, weaning mortality, average birth weight, and stillborn rates. The results indicated that sows treated with affected piglet intestinal contents had higher mortality (48.31%) and stillborn rates (20.96%) compared to those receiving the isolated virus (30.02% and 10.44%, respectively). These findings suggest that using an isolated virus can offer a safe, long-lasting, and specific immune response, underscoring the importance of thorough analysis of both systemic and mucosal immune responses against PEDV.