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MBio Feb 2024Since 2010, the genus has had the addition of 22 new species that more than tripled the number of species identified until 2010. Sixteen of these 22 new species are... (Review)
Review
Since 2010, the genus has had the addition of 22 new species that more than tripled the number of species identified until 2010. Sixteen of these 22 new species are distantly related to the type species, , and several of these present phenotypes that distinguish them from classical species (, , , , and ). These 22 newly described species also show that is more genetically diverse than previously estimated. While future studies and surveys are needed to clarify the distribution of these species, at least some of these species may not be widely spread, while other species may be frequently found spread to human-related settings (e.g., farms and processing facilities), and others may be adapted to specific environmental habitats. Here, we review the taxonomic, phylogenetic, and ecological characteristics of these new species identified since 2010 and re-iterate the suggestion of re-classification of some species into three new genera: , , and . We also provide a review of current detection issues and the relevance to food safety related to the identification of these new species. For example, several new non-pathogenic species could be misidentified as the pathogen , based on methods that do not target -specific virulence genes/factors, leading to unnecessary product recalls. Moreover, eight species in the proposed new genus are not good indicators of environmental conditions that could allow to grow since species are unable to grow at low temperatures.
Topics: Humans; Phylogeny; Listeria; Listeria monocytogenes; Virulence Factors; Food Safety
PubMed: 38126771
DOI: 10.1128/mbio.00938-23 -
Sichuan Da Xue Xue Bao. Yi Xue Ban =... Nov 2023To construct (LM) and (LI) balanced lethal systems expressing cervical cancer antigens, to study their basic biological characteristics, and to provide reference data...
OBJECTIVE
To construct (LM) and (LI) balanced lethal systems expressing cervical cancer antigens, to study their basic biological characteristics, and to provide reference data for the immunotherapy of cervical cancer.
METHODS
Through seamless cloning via ligation kit, the HPV16 67 fusion protein antigen gene constructed in our lab was spliced to the complement plasmid pCW-LM -Amp that contained the nutritional gene . Then, we replaced the ampicillin (Amp) resistance gene of the complement plasmid with the nutrition gene. The ligation reaction mixture was transformed into () recipient bacteria DH5αΔ and the complement plasmid pCW-67-LM -Ampfree, which expressed cervical cancer antigens and had no Amp resistance, was obtained by nutrition screening from the DH5αΔ. The plasmid pCW-67-LM -Ampfree was complemented into LMΔdd and LIΔdd, the attenuated nutrition-deficient strains with the virulence genes and and nutrition genes and deleted by electroporation, thereby obtaining LM and LI balanced lethal systems expressing cervical cancer antigen genes. The growth of the strains was observed. Western blot was performed to examine the status of antigen protein expression. PCR was performed to measure the passage stability of complement plasmid pCW-67-LM -Ampfree. Their basic biological characteristics were examined by biochemical reaction tests and hemolysis assay.
RESULTS
Two balanced lethal systems expressing cervical cancer antigen were successfully constructed. The HPV16 type E6E7 fusion protein was successfully expressed in the two balanced lethal systems. pCW-67-LM Ampfree, the positive plasmid expressing cervical cancer antigen, maintained stable existence in the two balanced lethal systems. The two balanced lethal systems expressing cervical cancer antigen showed significantly better recovery growth in comparison with nutrition deficiency strains. The results of biochemical reaction tests showed that most of the biochemical reaction of the two balanced lethal systems expressing cervical cancer antigen were consistent with those of attenuated strains. The two balanced lethal systems expressing cervical cancer antigen still maintained the hemolytic ability, although their hemolytic ability was slightly inferior to that of the balanced lethal systems not expressing cervical cancer antigen and the attenuated strains.
CONCLUSION
The two balanced lethal systems expressing cervical cancer antigen genes are constructed successfully. They display normal growth. The complement plasmid pCW-67-LM -Ampfree can maintain stable existence , showing little change in its biochemical characteristics and hemolytic ability. Further research should be conducted to investigate the potential of these two recombinant strains to be used as candidate strains for cervical cancer therapeutic vaccine.
Topics: Female; Humans; Uterine Cervical Neoplasms; Escherichia coli; Listeria; Listeria monocytogenes; Recombinant Proteins
PubMed: 38162066
DOI: 10.12182/20231160210