There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Since the outbreak of severe acute respiratory syndrome (SARS) 18 years ago, a large number of SARS-related coronaviruses (SARSr-CoVs) have been discovered in their natural reservoir host, bats1–4. Previous studies have shown that some bat SARSr-CoVs have the potential to infect humans5–7. Here we report the identification and characterization of a new coronavirus (2019-nCoV), which caused an epidemic of acute respiratory syndrome in humans in Wuhan, China. The epidemic, which started on 12 December 2019, had caused 2,794 laboratory-confirmed infections including 80 deaths by 26 January 2020. Full-length genome sequences were obtained from five patients at an early stage of the outbreak. The sequences are almost identical and share 79.6% sequence identity to SARS-CoV. Furthermore, we show that 2019-nCoV is 96% identical at the whole-genome level to a bat coronavirus. Pairwise protein sequence analysis of seven conserved non-structural proteins domains show that this virus belongs to the species of SARSr-CoV. In addition, 2019-nCoV virus isolated from the bronchoalveolar lavage fluid of a critically ill patient could be neutralized by sera from several patients. Notably, we confirmed that 2019-nCoV uses the same cell entry receptor—angiotensin converting enzyme II (ACE2)—as SARS-CoV. Characterization of full-length genome sequences from patients infected with a new coronavirus (2019-nCoV) shows that the sequences are nearly identical and indicates that the virus is related to a bat coronavirus.

/pdf/a-pneumonia-outbreak-associated-with-a-new-coronavirus-of-4uc8p3yu65.pdf

A pneumonia outbreak associated with a new coronavirus of probable bat origin

Statistical method for testing the neutral mutation hypothesis by DNA polymorphism.

Severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV) are two highly transmissible and pathogenic viruses that emerged in humans at the beginning of the 21st century. Both viruses likely originated in bats, and genetically diverse coronaviruses that are related to SARS-CoV and MERS-CoV were discovered in bats worldwide. In this Review, we summarize the current knowledge on the origin and evolution of these two pathogenic coronaviruses and discuss their receptor usage; we also highlight the diversity and potential of spillover of bat-borne coronaviruses, as evidenced by the recent spillover of swine acute diarrhoea syndrome coronavirus (SADS-CoV) to pigs. Coronaviruses have a broad host range and distribution, and some highly pathogenic lineages have spilled over to humans and animals. Here, Cui, Li and Shi explore the viral factors that enabled the emergence of diseases such as severe acute respiratory syndrome and Middle East respiratory syndrome.

/pdf/origin-and-evolution-of-pathogenic-coronaviruses-5eofmvbv9y.pdf

Origin and evolution of pathogenic coronaviruses

During the past decade the pesticidal bacterium Bacillus thuringiensis has been the subject of intensive research. These efforts have yielded considerable data about the complex relationships between the structure, mechanism of action, and genetics of the organism’s pesticidal crystal proteins, and a coherent picture of these relationships is beginning to emerge. Other studies have focused on the ecological role of the B. thuringiensis crystal proteins, their performance in agricultural and other natural settings, and the evolution of resistance mechanisms in target pests. Armed with this knowledge base and with the tools of modern biotechnology, researchers are now reporting promising results in engineering more-useful toxins and formulations, in creating transgenic plants that express pesticidal activity, and in constructing integrated management strategies to insure that these products are utilized with maximum efficiency and benefit.

Bacillus thuringiensis and Its Pesticidal Crystal Proteins

Insect pathogens as biological control agents: Back to the future.

https://www.fabinet.up.ac.za/publication/pdfs/2509-lacey_et_al_2001.pdf

Insect Pathogens as Biological Control Agents: Do They Have a Future?

: Insect-resistant transgenic plants have become an important tool for the protection of crops against insect pests. The acreage of insecticidal transgenic plants is expected to increase significantly in the near future. The bacterium Bacillus thuringiensis is currently the source of insecticidal proteins in commercial insect-resistant transgenic plants and will remain the most important source during the next decade. Insect resistance to B. thuringiensis Cry toxins is the main problem. Only one species, the diamondback moth, has evolved a resistance to B. thuringiensis-based formulations under field conditions. However, many other insect species were selected for resistance under laboratory conditions, indicating that there is a potential for evolution of resistance in most major pests. Many studies were conducted to elucidate the mode of action of the Cry toxins, the mechanisms and genetics of resistance, and the various factors influencing its development. This article reviews insect resistance...

Managing Insect Resistance to Plants Producing Bacillus thuringiensis Toxins

Selection of resistance in Spodoptera exigua (Hubner) to an HD-1 spore-crystal mixture, CryIC (HD-133) inclusion bodies, and trypsinized toxin from Bacillus thuringiensis subsp aizawai and B thuringiensis subsp entomocidus was attempted by using laboratory bioassays No resistance to the HD-1 spore-crystal mixture could be achieved after 20 generations of selection Significant levels of resistance (11-fold) to CryIC inclusion bodies expressed in Escherichia coli were observed after seven generations Subsequent selection of the CryIC-resistant population with trypsinized CryIC toxin resulted, after 21 generations of CryIC selection, in a population of S exigua that exhibited only 8% mortality at the highest toxin concentration tested (320 (mu)g/g), whereas the 50% lethal concentration was 430 (mu)g/g for the susceptible colony Insects resistant to CryIC toxin from HD-133 also were resistant to trypsinized CryIA(b), CryIC from B thuringiensis subsp entomocidus, CryIE-CryIC fusion protein (G27), CryIH, and CryIIA In vitro binding experiments with brush border membrane vesicles showed a twofold decrease in maximum CryIC binding, a fivefold difference in K(infd), and no difference in the concentration of binding sites for the CryIC-resistant insects compared with those for the susceptible insects Resistance to CryIC was significantly reduced by the addition of HD-1 spores Resistance to the CryIC toxin was still observed 12 generations after CryIC selection was removed These results suggest that, in S exigua, resistance to a single protein is more likely to occur than resistance to spore-crystal mixtures and that once resistance occurs, insects will be resistant to many other Cry proteins These results have important implications for devising S exigua resistance management strategies in the field

https://aem.asm.org/content/aem/61/6/2086.full.pdf

Development of Bacillus thuringiensis CryIC Resistance by Spodoptera exigua (Hubner) (Lepidoptera: Noctuidae).

A two-step strategy, named exclusive PCR or E-PCR, has been developed to overcome the main limitation of PCR, which is the detection of already-known sequences only. This strategy allows the ability to detect and further clone and sequence genes for which no specific primers are available and in which a variable region exists between two conserved regions. This approach has been applied to Bacillus thuringiensis cryI genes by the use of mixtures of degenerate and specific primers recognizing well-known sequences. The first step allows the accurate identification of already-characterized cryI genes by the use of three primers. During the second step, the same sets of primers are used to exclude known sequences and to positively detect cryI genes unrecognized by any specific primer. The method, as well as its application to detect, clone, and sequence a novel cryIB gene, is described in this article.

Roger Frutos

Papers

Insect pathogens as biological control agents: Back to the future.

Insect Pathogens as Biological Control Agents: Do They Have a Future?

Managing Insect Resistance to Plants Producing Bacillus thuringiensis Toxins

Development of Bacillus thuringiensis CryIC Resistance by Spodoptera exigua (Hubner) (Lepidoptera: Noctuidae).

PCR-based approach for detection of novel Bacillus thuringiensis cry genes