[Genomic characterization of food-borne Listeria monocytogenes isolates from Nanshan district of Shenzhen during 2009-2019].

Objective: The study aims to investigate the characteristic baseline information about genetic lineages, drug-resistance genes, virulence genes and evolutionary relationships of food-borne Listeria monocytogenes (Lm) isolates from Nanshan district of Shenzhen. Methods: The whole genomes of 46 Lm isolates during 2009-2019 were extracted and sequenced (Illumina PE-150, 100×). The CLC Genomics Workbench 12.0 was used to assemble and align Lm genomes, analyze their housekeeping genes, drug-resistance genes and virulence genes, and construct a k-mer phylogenetic tree. Results: After assembly, all genomes satisfied analytical conditions (contigs N50>20 kb). The medians of GC content, gene count and gene size were 38.3%, 5 960 and 2 952 608 bp, respectively. Based on the Lm genomic reference database, the local k-mer phylogenetic tree had 14 clusters of which the genetic distance was wide. The 46 Lm isolates were classified as Lineage 1 (21), Lineage 2 (23) and Lineage 3 (2). The most common ST type of Lineage 1 was ST87, followed by ST3, ST59, ST224 and ST429, whereas the major ST types of Lineage 2 included ST8 and ST9, the rest being ST121, ST155, ST199, ST204 and ST321. However, Lineage 3 only had ST299. The part of Lm strains carried five drug-resistance genes, such as fosX (17), tetM (6), dfrG (4), catB3 (1) and mefA (1). Furthermore, all strains possessed nine virulence genes, including flaA, iap, actA, hly, mpl, prfA, plcA, plcB and inlB. Nevertheless, six isolates and three of them respectively carried the mutant inlA and inlJ, and other two isolates lacked inlC. Conclusion: The food-borne Lm isolates from Nanshan district of Shenzhen presented genetic and evolutionary diversity. Noted that the drug-resistant strains, which also owned abundant virulence genes with specific functions, could lead to serious infections, particularly those isolates from raw poultry and Flammulina velutipes. It was implied that the local region was at risk due to Listeriosis by food. This study offered reference for prevention, control and treatment of Lm infection to the Greater Bay Area.

[Association between DRD2 gene polymorphisms and the dosage used on methadone maintenance treatment program].

Objective: To investigate the association between three single nucleotide polymorphism (SNP) genes DRD2 (rs1800497, rs6275, and rs1799978) and the dosage used on methadone maintenance treatment (MMT). Methods: From the methadone maintenance treatment centers, 257 MMT patients were recruited to participate in a case-control study and divided into two groups-control groups under low dosage (n=89) and case (n=168) group with high dosage. Quanto software was used to estimate the sample size as 180. Information related to social-demographic status, history on drug use and medication were collected. And DRD2 SNPs were genotyped to explore the relationship between polymorphism of DRD2 gene and the dosage of methadone maintenance treatment. Results: Distributions of DRD2 rs6275 between different groups were significantly different. Patients carrying TC genotype needed lower dose of methadone when compared to the patients that carrying CC genotype counterparts (OR=0.338, 95% CI: 0.115-0.986). Patients that carrying C allele at rs6275 needed lower methadone dose than those that carrying genotype TT (OR=0.352, 95% CI: 0.127-0.975). Distributions of genotypes, alles in the other two SNPs (rs1800497, rs1799978) were not significantly different between groups under different dosages. Conclusion: DRD2 rs6275 was associated with dosage of methadone used for the MMT patients. However, no significant associations were found between rs1800497, rs1799978 and the dosage of methadone.

[Association between ß-arrestin2 genetic polymorphism and response to methadone maintenance treatment in heroin-dependent patients in Han population in Hunan province].

OBJECTIVE: To study the distributions of three single nucleotide polymorphisms (SNPs) in ß-arrestin2 (ARRB2) which including rs3786047, rs1045280 and rs2036657 and to elucidate the relationship between these SNPs and response to methadone maintenance treatment (MMT) among heroin-dependent patients of Han ethnicity population in Hunan. METHODS: Han MMT patients were recruited in four random-chosen MMT clinics from Hunan province. Demographics, history of drug-use and MMT were recorded. ARRB2 SNPs were genotyped to determine the association between SNPs and response to MMT. RESULTS: Distributions of the three SNPs were in Hardy-Weinberg equilibrium in both groups (responders vs. non-responders). There was no statistical significance in the distribution frequency of genotype on rs3786047 (χ(2)=0.486 2, P=0.784), rs1045280 (χ(2)=1.591 9, P=0.451) and rs2036657 (χ(2)=1.061 5, P=0.588) in ARRB2 among the responders or the non-responders. CONCLUSION: Associations between the ARRB2 genotypes, rs3786047, rs1045280 and rs2036657, and MMT response in Han MMT patients in Hunan province did not appear.