Relational interaction between T-lymphocytes and SARS-CoV-2: A review.

Coronavirus disease 2019 (COVID-19) has turned out as one of the worst medical and economic misfortunes across the globe. The etiological agent, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a member of the Coronaviridae family and represents a disease manifestation from asymptomatic to severe respiratory damage. High transmissibility and contagious nature of the virus helps it to flourish in a large population. The immune system aids to retain the virus, but with accelerated cytokine secretion, it could transform into double edge sword resulting in unrestrained systemic inflammation which might become life-threatening. SARS-CoV-2 sets substantial impact on T-lymphocytes during its course of infection. The number of CD4+ T, CD8+ T, and Treg cells tend to decrease profoundly in case of severe illness. Besides, the virus modulates the CD4+ T/ CD8+ T and Treg/Th17 cells ratio and induces the functional exhaustion of T cells to make them inefficient. T cells define the pathogenesis of severe cases and provide major contributions in antiviral defense. Therefore, the apprehension of T-lymphocytes in SARS-CoV-2 infection would implicate in developing antivirals, disease control, and would broaden the way for vaccine formulation. Thus, the review depicts the significance of T-lymphocytes interaction with SARS-CoV-2. Keywords: SARS-CoV-2; COVID-19; T-lymphocytes; cytokine; inflammation; immune response.

Genetic studies of terminal regions of vaccine and field isolates of capripoxviruses.

Sheeppox and goatpox are two of the most important diseases associated with significant economic loss and impact on animal trade. In spite of the use of vaccines, outbreaks are being reported on several occasions. Therefore, deciphering the host specificity and virulence of sheeppox virus (SPPV) and goatpox virus (GTPV) is important in developing effective vaccines. It is opined that genes located in the terminal regions play a major role in determining host range and/or virulence. In the present study, nine isolates (6 GTPV and 3 SPPV; included both vaccine and virulent viruses) were genetically characterized by targeting 11 genes (7 host-range and 4 virulence genes) which are located in the terminal regions of capripoxviruses. In the genetic analyses, it was observed that there are several nucleotide and amino acid signatures which are specific for either SPPV or GTPV. However, surprisingly, none of the 11 genes could be able to differentiate the vaccine and field viruses of GTPV and SPPV. Our study indicates that the genes of the terminal regions may have a role in determining the host-specificity but the involvemet in determinatin of virulence/attenuation is not certain at least for the isolates used in the current study. Therefore, it is likely that some other genes located in terminal/central regions may also play a role in determination of virulence and pathogenesis which needs to be confirmed by whole-genome sequencing of several vaccine and virulent viruses.