Virus fuses with vesicle and its RNA is releasedThe virus uses its surface spike protein to lock onto ACE2 receptors on the surface of human cells. Once inside, these cells translate the virus's RNA to produce more viruses. Specialized 'antigen-presenting cells' engulf the virus and display portions of it to activate T-helper cells.

esearchers are rushing to track the concerning rise of a new variant of the SARS-CoV-2 coronavirus that causes COVID-19. The variant harbours a large number of the mutations found in other variants, including Delta, and it seems to be spreading quickly across South Africa.

When COVID-19 spread around the globe this year, David Montefiori wondered how the deadly virus behind the pandemic might be changing as it passed from person to person. Montefiori is a virologist who has spent much of his career studying how chance mutations in HIV help it to evade the immune system. The same thing might happen with SARS-CoV-2, he thought.In March, Montefiori, who directs an AIDS-vaccine research laboratory at Duke University in Durham, North Carolina, contacted Bette Korber, an expert in HIV evolution and a long-time collaborator. Korber, a computational biologist at the Los Alamos National Laboratory (LANL) in New Mexico, had already Bases A: adenine C: cytosine G: guanine U: uracil Spike protein Virus surface"It is a possibility that the virus will acquire mutations that change its susceptibility to antibodies and immunity."

The objective of this study was to determine the effects of a yeast (Saccharomyces cerevisiae) culture on lactate utilization and cellulose digestion by ruminal bacteria. Growth of Selenomonas ruminantium HD4 in medium that contained 5 g/L of DL-lactate, Trypticase, and yeast extract was stimulated 7 and 15% by 1 and 5% (vol/vol) yeast culture filtrate respectively. The 1 and 5% yeast culture filtrate stimulated growth of Selenomonas ruminantium H18 and Megasphaera elsdenii B159 and T81 on 5 g/L of DL-lactate in medium without Trypticase or yeast extract. Growth of Fibrobacter succinogenes S85 and Ruminococcus albus B199 on 6 g/L of cellobiose was stimulated by the addition of yeast culture filtrate to medium without Trypticase or yeast extract. The yeast culture filtrate increased the concentrations of acetate and total volatile fatty acids that were produced by Sel. ruminantium HD4 and increased the concentrations of propionate and total volatile fatty acids that were produced by Sel. ruminantium H18 but did not alter end-product formation of M. elsdenii or cellulolytic bacteria. Treatment with yeast culture increased the initial rate but not the extent of cellulose digestion by F. succinogenes S85 and Ruminococcus flavefaciens FD1. Collectively, these results suggest that yeast culture provides soluble growth factors (i.e., organic acids, B vitamins, and amino acids) that stimulate growth of ruminal bacteria that utilize lactate and digest cellulose.

A n artificial intelligence (AI) network developed by Google AI offshoot DeepMind has made a gargantuan leap in solving one of biology's grandest challenges -determining a protein's 3D shape from its amino-acid sequence.DeepMind's program, called AlphaFold, outperformed around 100 other teams in a biennial protein-structure prediction challenge called CASP, short for Critical Assessment of Structure Prediction. The

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Barely a week has elapsed since scientists in Botswana and South Africa alerted the world to a fast-spreading SARS-CoV-2 variant now known as Omicron. Researchers worldwide are racing to understand the threat that the variant -now confirmed in more than 30 countries -poses to the world. Yet it might take scientists weeks to paint a more complete picture of Omicron, and to gain an understanding of its transmissibility and severity, as well as its potential to evade vaccines and cause reinfections."There is so little understanding of what's going on, and that's true even for scientists," says Senjuti Saha, a molecular microbiologist and director of the Child Health Research Foundation in Dhaka, Bangladesh.Nature rounds up what scientists know so far about the Omicron variant.

Estimates of COVID-19's case fatality rate-the proportion of infected people who die-suggest that the coronavirus is less deadly than the pathogens behind other large-scale outbreaks, such as those of SARS (severe acute respiratory syndrome), MERS (Middle East respiratory syndrome) and Ebola. But it seems to spread more easily. Calculations of the virus's 'basic reproduction number' (R 0) suggest that each infected person will pass the virus to an average of 2-2.5 people. Like the case fatality rate, R 0 is an estimate that varies considerably, and is likely to be revised. 0 2 1 3 5 4