[Research Progress in Antibody Responses Against SARS-CoV-2 Variants of Concern].

So far,the coronavirus disease 2019(COVID-19)has been persisting for nearly three years,infecting about 700 million people and causing more than 6 million deaths,which has seriously affected the human society.According to Global Initiative on Sharing All Influenza Data,there are more than 12 million SARS-CoV-2 variants,of which the five major variants of concern are Alpha,Beta,Gamma,Delta and Omicron.Their infectivity,pathogencity,and neutralization resistance have changed greatly compared with the original strain,which has brought great pressure to the prevention and control of the pandemic.Antibody level testing is critical for confirming infection,epidemiological investigation,vaccine development,and neutralizing drug preparation.Focusing on the humoral immunity against SARS-CoV-2,this paper introduces the mutation sites,neutralization resistance,and vaccination efficacy of the five variants of concern,and briefly summarizes the evolutionary characteristics,future mutation directions,and host immunity.

Rare manifestation of familial vitreous amyloidosis caused by Gly103Arg transthyretin.

AIM: To identify and analyze the genotype of the patients with special ocular manifestations of familial vitreous amyloidosis (FVA) in a Chinese Han family. METHODS: Pars plana vitrectomy (PPV) surgery was performed on a 52-year-old Chinese woman presented with vitreous amyloidosis and progressive visual impairment, without evidence of cardiac, renal, gastrointestinal, central nervous system or peripheral nervous system dysfunction. During the surgery, the patient presented with a gray-white dense and thick cotton wool-like change in the vitreous body, accompanied by complete retinal detachment. Additionally, hard, free and movable yellow-white deposits were observed in the posterior pole and surrounding retina, the vitreous and subretinal deposits were examined by Congo red staining and immunohistochemical pathological examination, and whole exome sequencing was performed on blood samples from the patient and her cousin. RESULTS: During the operation, it was discovered that there was a complete detachment of the retina and a significant amount of hard, free-floating yellow-white deposits were observed beneath the posterior pole and surrounding retina. This is an exceedingly rare ocular manifestation. Pathological examination of the vitreous and subretinal deposit specimens revealed positive Congo red staining, as well as elevated vascular endothelial growth factor (VEGF) expression in vascular endothelial cells within the sediment specimens upon immunohistochemical examination. The patient and her cousin both exhibited a heterozygous mutation in Glyl03Arg within the transthyretin (TTR) gene, resulting in a substitution of glycine (Gly) at position 103 with arginine (Arg). CONCLUSION: FVA may present with various ocular manifestations, but panretinal detachment is a rare occurrence. In cases where retinal detachment persists for an extended period of time, amyloid deposits may form under the retina through retinal tears, leading to subretinal deposits that can impede retinal reattachment and negatively impact visual prognosis. Elevated levels of VEGF in the eyes of FVA patients may indicate an overexpression state, necessitating careful postoperative follow-up. The heterozygous mutation Gly103Arg may represent a unique pathogenic site in Chinese individuals.

Development of L-tryptophan production strains by defined genetic modification in Escherichia coli.

Construction and improvement of industrial strains play a central role in the commercial development of microbial fermentation processes. L-tryptophan producers have usually been developed by classical random mutagenesis due to its complicated metabolic network and regulatory mechanism. However, in the present study, an L-tryptophan overproducing Escherichia coli strain was developed by defined genetic modification methodology. Feedback inhibitions of 3-deoxy-D-arabinoheptulosonate 7-phosphate synthase (AroF) and anthranilate synthase (TrpED) were eliminated by site-directed mutagenesis. Expression of deregulated AroF and TrpED was achieved by using a temperature-inducible expression plasmid pSV. Transcriptional regulation of trp repressor was removed by deleting trpR. Pathway for L-Trp degradation was removed by deleting tnaA. L-phenylalanine and L-tyrosine biosynthesis pathways that compete with L-tryptophan biosynthesis were blocked by deleting their critical genes (pheA and tyrA). The final engineered E. coli can produce 13.3 g/l of L-tryptophan. Fermentation characteristics of the engineered strains were also analyzed.