Virological characteristics of the SARS-CoV-2 Omicron XBB.1.5 variant

Circulation of SARS-CoV-2 Omicron XBB has resulted in the emergence of XBB.1.5, a new Variant of Interest. Our phylogenetic analysis suggests that XBB.1.5 evolved from XBB.1 by acquiring the S486P spike (S) mutation, subsequent to the acquisition of a nonsense mutation in ORF8. Neutralization assays showed similar abilities of immune escape between XBB.1.5 and XBB.1. We determine the structural basis for the interaction between human ACE2 and the S protein of XBB.1.5, showing similar overall structures between the S proteins of XBB.1 and XBB.1.5. We provide the intrinsic pathogenicity of XBB.1 and XBB.1.5 in hamsters. Importantly, we find that the ORF8 nonsense mutation of XBB.1.5 resulted in impairment of MHC suppression. In vivo experiments using recombinant viruses reveal that the XBB.1.5 mutations are involved with reduced virulence of XBB.1.5. Together, our study identifies the two viral functions defined the difference between XBB.1 and XBB.1.5.

Virological characteristics of the SARS-CoV-2 XBB variant derived from recombination of two Omicron subvariants

In late 2022, SARS-CoV-2 Omicron subvariants have become highly diversified, and XBB is spreading rapidly around the world. Our phylogenetic analyses suggested that XBB emerged through the recombination of two cocirculating BA.2 lineages, BJ.1 and BM.1.1.1 (a progeny of BA.2.75), during the summer of 2022. XBB.1 is the variant most profoundly resistant to BA.2/5 breakthrough infection sera to date and is more fusogenic than BA.2.75. The recombination breakpoint is located in the receptor-binding domain of spike, and each region of the recombinant spike confers immune evasion and increases fusogenicity. We further provide the structural basis for the interaction between XBB.1 spike and human ACE2. Finally, the intrinsic pathogenicity of XBB.1 in male hamsters is comparable to or even lower than that of BA.2.75. Our multiscale investigation provides evidence suggesting that XBB is the first observed SARS-CoV-2 variant to increase its fitness through recombination rather than substitutions.

Convergent evolution of SARS-CoV-2 Omicron subvariants leading to the emergence of BQ.1.1 variant

In late 2022, various Omicron subvariants emerged and cocirculated worldwide. These variants convergently acquired amino acid substitutions at critical residues in the spike protein, including residues R346, K444, L452, N460, and F486. Here, we characterize the convergent evolution of Omicron subvariants and the properties of one recent lineage of concern, BQ.1.1. Our phylogenetic analysis suggests that these five substitutions are recurrently acquired, particularly in younger Omicron lineages. Epidemic dynamics modelling suggests that the five substitutions increase viral fitness, and a large proportion of the fitness variation within Omicron lineages can be explained by these substitutions. Compared to BA.5, BQ.1.1 evades breakthrough BA.2 and BA.5 infection sera more efficiently, as demonstrated by neutralization assays. The pathogenicity of BQ.1.1 in hamsters is lower than that of BA.5. Our multiscale investigations illuminate the evolutionary rules governing the convergent evolution for known Omicron lineages as of 2022.

Virological characteristics of the SARS-CoV-2 Omicron BA.2 subvariants, including BA.4 and BA.5

After the global spread of the SARS-CoV-2 Omicron BA.2, some BA.2 subvariants, including BA.2.9.1, BA.2.11, BA.2.12.1, BA.4, and BA.5, emerged in multiple countries. Our statistical analysis showed that the effective reproduction numbers of these BA.2 subvariants are greater than that of the original BA.2. Neutralization experiments revealed that the immunity induced by BA.1/2 infections is less effective against BA.4/5. Cell culture experiments showed that BA.2.12.1 and BA.4/5 replicate more efficiently in human alveolar epithelial cells than BA.2, and particularly, BA.4/5 is more fusogenic than BA.2. We further provided the structure of the BA.4/5 spike receptor-binding domain that binds to human ACE2 and considered how the substitutions in the BA.4/5 spike play roles in ACE2 binding and immune evasion. Moreover, experiments using hamsters suggested that BA.4/5 is more pathogenic than BA.2. Our multiscale investigations suggest that the risk of BA.2 subvariants, particularly BA.4/5, to global health is greater than that of original BA.2.

Effects of Pleurotus ostreatus on Blood Pressure and Glycemic Status of Hypertensive Diabetic Male Volunteers

Different species of mushrooms are being used increasingly for their nutritional and medicinal values. They are used in traditional medical practice in the treatment and prevention of diabetes, obesity, heart diesaes, hyperacidity, cancer and hypertension. This study was designed to see the effects of Pleurotus ostreatus on blood pressure and glycemic status of hypertensive diabetic male volunteers. The study was carried out in the National Mushroom development and Extension Center (NAMDEC) laboratory, Savar, Dhaka in collaboration with the Department of Pharmacy along with the Department of Biochemistry and Molecular Biology, Jahangirnagar University. A total of 27 hypertensive male volunteers suffering from type 2 diabetes mellitus with age range of 32 to 68 years, who were free from renal impairment and other known acute or chronic diseases were included in the study. Blood pressure, fasting plasma glucose, HbA1c and serum creatinine were measured before and after 3 months of regular intake of 3 grams mushroom powder capsule daily in in 3 divided doses. However they were allowed to continue the drugs they were taking already. The study showed that after 3 months of regular intake of Pleurotus ostreatus mushroom, both systolic and diastolic blood pressure decreased significantly (p<0.001). It was also observed that, Pleurotus ostreatus decreased fasting plasma glucose level significantly (p<0.001). Reduction of HbA1c % observed after 3 months of mushroom intake was found to be significant (p<0.001). But there was no significant change of plasma creatinine level (p>0.05) indicating Pleurotus ostreatus has no detrimental effect on renal system. From the study, it can be said that, Pleurotus ostreatus mushroom intake improves glycemic status and blood pressure control in diabetic hypertensive subjects. DOI: http://dx.doi.org/10.3329/bjmb.v6i1.13280 Bangladesh J Med Biochem 2013; 6(1): 5-10

Effect of Bishkatali, Polygonum hydropiper L. plant extracts against the red flour beetle, Tribolium castaneum Herbst

Toxicity, repellency and residual effects of Bishkatali plant extracts in chloroform and ethyl alcohol solvents were evaluated against the red flour beetle. Five concentrations viz. 500, 250, 125, 62.5 and 31.25mg/ml of Bishkatali plant extracts of both solvents were used in the experiment. The plant extracts in both solvents were moderately toxic to Tribolium castaneum. The toxicity of ethyl alcohol extract was more than chloroform extract after 24 and 72 hours treatment on the insect. Bishkatali plant extract in both solvents showed strong repellency against T. castaneum in which chloroform extract was better than ethyl alcohol extract. The rate of repellency was increased with the increment of concentration. Both the extracts have produced remarkable residual effect in reducing the progeny of T. castaneum. The lowest numbers of F1 adult progeny (32.7, 25.3 and 27.0) emerged from the wheat flour treated with 500mg/10g chloroform extract when parent released at 7, 12, 17 days after treatment respectively. Whereas with 500mg/10g ethyl alcohol extract, 38.0, 29.7 and 30.3 F1 adult progeny emerged when parents released at 7, 12, 17 days after treatment respectively. Bishkatali plant extracts in both chloroform and ethyl alcohol had remarkable residual effects on T. castaneum by reducing the production of F1 progeny and/or by increasing the population mortality. Key words: Botanical, solvent, red flour beetle, mortality, progeny, repellency, residual Univ. j. zool. Rajshahi Univ. Vol. 26, 2007. pp. 93-97