Comparative Structural Analyses of Selected Spike Protein-RBD Mutations in SARS-CoV-2 Lineages

The severity of the covid 19 has been observed throughout the world as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) had spread globally claiming more than 2 million lives and left a devastating impact on peoples life. Recently several virulent mutant strains of this virus, such as the B.1.1.7, B.1.351, and P1 lineages have emerged. These strains are predominantly observed in UK, South Africa and Brazil. Another extremely pathogenic B.1.617 lineage and its sub-lineages, first detected in India, are now affecting some countries at notably stronger spread-rates. This paper computationally examines the time-based structures of B.1.1.7, B.1.351, P1 lineages with selected spike protein mutations. Additionally, the mutations in the more recently found B.1.617 lineage and some of its sub-lineages are explored, and the implications for multiple point mutations of the spike proteins receptor-binding domain (RBD) are described.

Genomic analysis of a virulent and a less virulent strain of the entomopathogenic fungus Beauveria bassiana, using restriction fragment length polymorphisms

The genomic DNA of two strains of the entomopathogenic fungus Beauveria bassiana, strain GK2016, a "wild type" (virulent), and strain GK2051, a less virulent mutant to grasshoppers, was digested with 12 restriction endonucleases. Gel electrophoresis conditions were established to show restriction fragment length patterns visually in the digested DNA stained with ethidium bromide. The less virulent mutant was generated by ultraviolet illumination of conidiospores at a 95% lethal dose. Both strains of the fungi were identical in morphology as well as in 16 of 22 API-ZYM kit enzyme assays. Differences in levels of total enzyme activity were observed for esterase, esterase–lipase, (β-galactosidase, chitinase, and protease. A Neurospora crassa β-tubulin gene (heterologous gene) and two homologous DNA probes (pJK16 and pJK18) hybridized to several specific DNA bands in B. bassiana strain GK2016 but not in strain GK2051. Strain GK2051 gave different restriction fragment length patterns when compared with its parent strain. Taken together, the data show restriction fragment length differences between the genomic DNA of the two strains, including the loss of some DNA sequences from the mutant strain, which may be involved in pathogenicity. Finally, B. bassiana GK2016 contains a β-tubulin gene with at least partial homology to that of N. crassa. Key words: restriction fragment length polymorphism, entomopathogen, Beauveria bassiana, bioinsecticide, filamentous fungi.

A comparison of the protective effect against Mengo virus infection in mice of interferons induced by polyI: C and Mengo virus

PolyI: C (complexed polyinosinic and polycytidylic acids) has been demonstrated to protect mice against infection with lethal doses of a highly virulent mutant of Mengo virus. However, the serum interferon titers it induced were considerably lower and of much shorter duration than the interferon titers induced by infection with the Mengo virus mutant. Evidence has been obtained that the interferon induced by polyI: C is as effective against Mengo virus infection as polyI: C itself. It has also been shown that, unit for unit (measured by the plaque reduction of vesicular stomatitis virus), the polyI: C-induced interferon is much more effective against Mengo virus infection than the Mengo virus-induced interferon itself.

Dissemination and immunogenicity of live TRIC agent in baboons after parenteral injection: II. Experiments with a ‘slow-killing’ strain

SUMMARYAfter a single subcutaneous injection into baboons the MRC-4 strain of trachoma/inclusion conjunctivitis (TRIC) agent underwent limited multiplication at the injection site, but was then eliminated rapidly from the skin and regional lymph nodes. Forty-eight hours after a single intravenous injection, but not thereafter, it appeared in the peripheral lymph nodes and spleen. The single parenteral injections failed to immunize baboons against conjunctival challenge with the homologous strain. These findings contrasted with those previously reported for the more virulent mutant, MRC-4 f, which multiplied readily in the skin, lymph nodes and spleen, persisted in these tissues up to 3 weeks after injection, and conferred good immunity to conjunctival challenge with MRC-4. The difference in behaviour of MRC-4 and MRC-4 f might be accounted for, at least in part, by the use of a smaller inoculum of live MRC-4; but similar findings in guinea-pigs, reported elsewhere, suggest that the differences observed are real. In conjunction with previous work, the present study suggests that the immunogenicity of TRIC agent is closely related to the mass of antigen that can be administered to or propagated within the recipient.We are grateful to Mr D. Venters for his able technical assistance.