[Combined application of field epidemiology and laboratory etiology analysis in the investigation of a foodborne disease outbreak in Xinjiang uygur Autonomous Region, 2016]

Objectives: To analyze the causes of a foodborne outbreak in rural areas of Xinjiang between April 2 and April 5 in 2016. Methods: Cases and the relevant background information were obtained by consulting outpatient records of local health centers and regional people's hospitals and interviewing doctors and residents. All samples were collected by the laboratory test through epidemiological and food hygiene investigations. The χ² test (Fisher's exact probability method) was used to compare differences in incidence rates. Molecular typing, virulence genes and single nucleotide polymorphisms (SNPS) were analyzed by using Pulsed Field Gel Electrophoresis (PFGE) and Whole Genome Sequencing (WGS). Results: A total of 142 cases were found in this study, with incidence rate at 5.7‰ (142/24 979). Among all cases, the main symptoms were nausea (94%), vomiting (92%) and abdominal pain (67%), and the incubation period was about 2 h (1-7.5 h). There were 16 Staphylococcus aureus isolates identified and all of them could produce A+C+E mixed enterotoxin. PFGE showed 100% homology. WGS further revealed that there were 9 and 1 strains contained by Sequence Type 1 (ST1) and ST5405, respectively. All ST1 strains were in the same clade on the genome tree. Among these, 7 strains shared close proximity (74 SNPs) and 2 strains shared close relationships as well (127 SNPs). The S. aureus isolates that caused the outbreak were introduced by a mutant isolate from the milk supply station. Conclusions: This foodborne outbreak was mainly caused by Staphylococcus aureus contamination.

Polymorphisms of KAP6, KAP7, and KAP8 genes in four Chinese sheep breeds

High glycine-tyrosine proteins (HGTPs), also known as keratin-associated proteins (KAPs), play a key role in the major structures and mechanical properties of wool fiber. Sheep HGTPs consist of three multigene families: KAP6, KAP7, and KAP8 genes. Polymorphisms of these three genes have been proposed to have important effects on wool fiber traits. The aim of the present study was to identify polymorphisms of the KAP6, KAP7, and KAP8 genes in four sheep breeds, including Chinese Merino superfine wool sheep, Hu sheep, a Merino x Hu crossed breed, and Romney sheep. Polymerase chain reaction (PCR) product direct sequencing, PCR-single-strand conformation polymorphism, and cloned sequencing methods were used to find genetic variation and identify polymorphisms in these genes. The Mutation Surveyor v3.97 software was used to analyze the sequences. These methods revealed six different sequences of the KAP6 gene, two different sequences of the KAP7 gene, and five different sequences of the KAP8 gene. Accordingly, three (with frequencies>1%) single nucleotide polymorphisms (SNPs) of the KAP6 gene, one SNP of the KAP7 gene, and five SNPs of the KAP8 gene were detected. Interestingly, some of these sequences were present in only certain sheep breeds, thereby suggesting that these special allele sequences could be used as candidate genes of wool characteristics in further studies.

The relationship between MHC-DRB1 gene second exon polymorphism and hydatidosis resistance of Chinese Merino (Sinkiang Junken type), Kazakh and Duolang sheep

The present study aimed at detecting the association of ovine major histocompatibility complex class II (Ovar II) DRB1 gene second exon and susceptibility or resistance to hydatidosis in three sheep breeds of Sinkiang. The MHC-DRB1 second exon was amplified by polymerase chain reaction (PCR) from DNA samples of healthy sheep and sheep with hydatidosis. PCR products were characterized by the restriction fragment length polymorphism (RFLP) technique. Five restriction enzymes, Mval, Haelll, Sacl, Sacll, Hin1l, were used, yielding 14 alleles and 31 restriction patterns. Frequencies of patterns Mvalbc, Hin1lab, Sacllab, Haelllde, Haellldf, Haellldd (P < 0.01) in Kazakh sheep, Saclab (P < 0.05) in Duolang sheep, and Haelllab, Haelllce, Haelllde, Haelllee (P < 0.01) in Chinese Merino (Sinkiang Junken type) sheep, were significantly higher in healthy sheep compared with infected sheep. These results indicated a strong association between these patterns and hydatidosis resistance. In contrast, the frequencies of Mvalbb, Saclaa, Hinl lbb, Haelllef (P < 0.01) and Haelllab (P < 0.05) in Kazakh sheep, Saclbb, Haelllae, Hin1lab (P < 0.05), Haelllaa, Haelllbe, Haelllef (P < 0.01) in Duolang sheep, Sacllaa (P < 0.05) and Haelllbd, Hin1lbb, Haelllcf, Haelllef (P < 0.01) in Chinese Merino sheep (Sinkiang Junken type) were significantly lower in healthy sheep compared with infected sheep. This indicated a strong association between these patterns and hydatidosis susceptibility. In addition, sheep with the pattern of Haelllef demonstrated a high hydatidosis susceptibility (P < 0.01) in all three breeds, while sheep with the pattern Haelllde demonstrated significant hydatidosis resistance (P < 0.01) in Kazakh and Chinese Merino sheep (Sinkiang Junken type). These results suggest that the Ovar-DRB1 gene plays a role in resistance to hydatidosis infection in the three sheep breeds.

In vitro study on the influence of strontium-doped calcium polyphosphate on the angiogenesis-related behaviors of HUVECs

Angiogenesis is of great importance in bone tissue engineering, and has gained large attention in the past decade. Strontium-doped calcium polyphosphate (SCPP) is a novel biodegradable material which has been proved to be able to promote in vivo angiogenesis during bone regeneration. An in vitro culture system was developed in the present work to examine its influence on angiogenesis-related behaviors of human umbilical vein endothelial cells (HUVECs), including cell adhesion, spreading, proliferation and migration. The effects of microtopography, chemical property and the ingredients in the degradation fluid (DF) on cell behaviors were discussed. The results showed that cells attached and spread better on SCPP scaffold than on calcium polyphosphate (CPP), which might partially result from the less rough surface of SCPP scaffold and the less hydrogel formed on the surface. In addition, cell proliferation was significantly improved when treated with SCPP DF compared with the treatment with CPP DF. Statistical analysis indicated that Sr(2+) in SCPP DF might be the main reason for the improved cell proliferation. Moreover, cell migration, another important step during angiogenesis, was evidently stimulated by SCPP DF. The improved in vivo angiogenesis by SCPP might be assigned to its better surface properties and strontium in the DF. This work also provides a new method for in vitro evaluation of biodegradable materials' potential effects on angiogenesis.

Comparative cutaneous testing with purified protein derivative and the antigen complex A60 in vaccinated subjects and tuberculosis patients

Some 840 bacille Calmette-Guérin (BCG)-vaccinated healthy controls and tuberculosis patients from two Chinese hospitals were submitted to comparative skin tests with purified protein derivative of tuberculin (PPD; as reference) and with the antigen complex A60 from Mycobacterium bovis BCG. In a first trial, including 581 persons (185 healthy juveniles, 180 healthy adults and 216 tuberculosis patients), a limited dose of A60 (1 microgram) was used. Performance of the A60 test was similar to that of 5 I.U. PPD for controls (cut-off values = 5 mm induration diameter), but lower than that seen for tuberculosis patients (10 mm cut-off values). A second survey was conducted on 259 persons (109 recently revaccinated healthy persons, considered as tuberculin-negative in the first trial, and 150 tuberculosis patients), using a higher dose of A60 (2 micrograms) and the same dose of PPD (5 I.U.). Similar results were obtained with the two tests in all cases, thus supporting the possibility of PPD replacement by A60 in cutaneous testing. The pattern of induration diameter distribution in healthy subjects who took part in the first testing round (64% positively rate) was displaced to the inactivity side (with a peak at 5 to 9-mm diameter), in comparison with the second round (90% positivity rate and peak at 10-14 mm). This indicates a progressive fading of cellular immunity reactions after BCG vaccination. In tuberculosis patients, no correlation was found among the following three parameters: positivity at cutaneous testing (with PPD or A60), titer of anti-A60 mycobacterial immunoglobulins in blood (IgG titer higher than cut-off line) and presence of mycobacteria in sputum.

Serological analysis of pulmonary and extrapulmonary tuberculosis with enzyme-linked immunosorbent assays for anti-A60 immunoglobulins

IgA, IgG, and IgM antibodies to mycobacterial antigen A60 were measured by ELISA in blood, pleural fluid, and cerebrospinal fluid from 560 patients with pulmonary and/or extrapulmonary tuberculosis who were being treated at hospitals in northern China and from 734 uninfected controls. Among 529 healthy persons (most of whom had been vaccinated with bacille Calmette-Guérin [BCG] and 287 of whom were tuberculin-positive), the rate of false-positive results was negligible; this observation ruled out interference of remote BCG vaccination with A60 assays at the chosen cutoff level. Rates of positivity for IgM and IgG, respectively, were 80% and 36% among patients with active primary pulmonary tuberculosis, 31% and 88.5% among patients with active postprimary pulmonary tuberculosis, 0 and 41% among patients with inactive pulmonary tuberculosis, and 30%-61% and 69%-86% among patients with extrapulmonary tuberculosis. Paired samples of blood and pleural fluid from patients with pleurisy contained IgA antibody to A60 at equal titers; in contrast, most patients with tuberculous meningitis (100% of whom had a positive ELISA result) had higher levels of IgG antibody to A60 in cerebrospinal fluid than in blood--proof of intrathecal synthesis.

Analysis of tuberculous meningitis cases by an immunoblotting assay based on a mycobacterial antigen complex

Tuberculous meningitis cases were analyzed by an immunoblotting test based on Mycobacterium bovis BCG antigen complex A60. Anti-A60 immunoglobulin G (IgG) in cerebrospinal fluid (CSF) allowed early diagnosis, and concentrations decreased after recovery. In primary meningitis forms, anti-A60 IgGs were intrathecally synthesized and specific oligoclonal IgGs were present in CSF. In meningeal complications of pulmonary tuberculosis, there were matching titers of anti-A60 IgG in blood and CSF (mirror pattern). Correlation between CSF-restricted patterns and CSF pleocytosis was shown.