Publications by authors named "Zheng Xiaocong"

10 Publications

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Fraudulent antibiotic products on the market for aquaculture use.

Prev Vet Med 2020 Aug 9;181:105052. Epub 2020 Jun 9.

Department of Systems Engineering and Engineering Management, School of Data Science, City University of Hong Kong, Hong Kong.

Antibiotics in aquaculture are used to treat bacterial infections. In order for these products to work effectively fish need to be properly dosed. One of the emerging issues in aquaculture is under-dosing large populations of fish with antibiotics. This happens inadvertently for a number of reasons including the use of fraudulent medications. In this study we evaluated 17 antibiotic products (8 florfenicol and 9 oxytetracycline brands purchased in Asia) by HPLC to determine if the product labels accurately reflected the active pharmaceutical ingredient (API) in the package. We determined authenticity scores for different batches of products at two separate laboratories by comparing the observed API to the label API concentration. We found that 48 % of the antibiotic batches had authenticity scores below 80 % (i.e. observed API in package was at least 20 % less than the label API concentration). Further, there were 9 or the 31 batches of drugs tested had no measureable API. Some products had variation in their authenticity scores between batches making it difficult to rely on a brand. The price of florfenicol products may help identify products with low authenticity scores, but in the case of oxytetracycline, the price of all the products tested was relatively similar. The findings in this study suggest that not all florfenicol and oxytetracycline antibiotic products on the market in Asia have API concentrations indicated on their labels. This could be problematic for medicating fish on aquaculture farms.
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http://dx.doi.org/10.1016/j.prevetmed.2020.105052DOI Listing
August 2020

Comparison of insight and clinical variables in homeless and non-homeless psychiatric inpatients in China.

Psychiatry Res 2017 09 9;255:13-16. Epub 2017 May 9.

Unit of Psychiatry, Faculty of Health Sciences, University of Macau, Macao SAR, China. Electronic address:

There are no published data on insight in homeless patients with psychiatric disorders in China. This study examined insight in homeless and non-homeless Chinese psychiatric inpatients in relation to demographic and clinical variables. A total of 278 homeless and 222 non-homeless inpatients matched in age and gender were included in the study. Demographic and clinical characteristics were collected based on a review of medical charts and a clinical interview with standardized instruments. Insight was evaluated with the Insight and Treatment Attitudes Questionnaire. Altogether 20.5% of homeless inpatients and 43.7% of the non-homeless controls had good insight. Compared with homeless inpatients with impaired insight, homeless inpatients with good insight had higher physical quality of life, longer duration of illness and less severe positive and negative symptoms. Impaired insight appeared more common in homeless psychiatric inpatients in China. Further studies should address the need for effective therapeutic interventions that promote homeless patients' insight.
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http://dx.doi.org/10.1016/j.psychres.2017.04.066DOI Listing
September 2017

Analytical validation of a reverse transcriptase droplet digital PCR (RT-ddPCR) for quantitative detection of infectious hematopoietic necrosis virus.

J Virol Methods 2017 07 24;245:73-80. Epub 2017 Mar 24.

Shenzhen Entry-exit Inspection and Quarantine Bureau, Shenzhen, 518045, People's Republic of China; Shenzhen Academy of Inspection and Quarantine Sciences, Shenzhen, 518045, People's Republic of China. Electronic address:

Infectious hematopoietic necrosis virus (IHNV) is an important pathogen of salmonid fishes. A validated universal reverse transcriptase quantitative PCR (RT-qPCR) assay that can quantify levels of IHNV in fish tissues has been previously reported. In the present study, we adapted the published set of IHNV primers and probe for use in a reverse-transcriptase droplet digital PCR (RT-ddPCR) assay for quantification of the virus in fish tissue samples. The RT-ddPCR and RT-qPCR assays detected 13 phylogenetically diverse IHNV strains, but neither assay produced detectable amplification when RNA from other fish viruses was used. The RT-ddPCR assay had a limit of detection (LOD) equating to 2.2 plaque forming units (PFU)/μl while the LOD for the RT-qPCR was 0.2 PFU/μl. Good agreement (69.4-100%) between assays was observed when used to detect IHNV RNA in cell culture supernatant and tissues from IHNV infected rainbow trout (Oncorhynchus mykiss) and arctic char (Salvelinus alpinus). Estimates of RNA copy number produced by the two assays were significantly correlated but the RT-qPCR consistently produced higher estimates than the RT-ddPCR. The analytical properties of the N gene RT-ddPCR test indicated that this method may be useful to assess IHNV RNA copy number for research and diagnostic purposes. Future work is needed to establish the within and between laboratory diagnostic performance of the RT-ddPCR assay.
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http://dx.doi.org/10.1016/j.jviromet.2017.03.010DOI Listing
July 2017

Identification of Infectious Salmon Anaemia Virus from Imported Iced Atlantic Salmons.

Bing Du Xue Bao 2017 Jan;33(1):96-102

Infectious Salmon anaemia virus (ISAV) has become a threat to the salmon industry worldwide and has caused considerable economic loss. In the present study, 9 suspect cases of ISAV infection were identified from iced Atlantic salmons imported from Norway in 2014 through Shenzhen port (Shenzhen, China) using methods recommended by the World Organization for Animal Health. However, the results of virus isolation were negative., Based on the sequence analysis of ISAV segment 6, the 9 ISAV isolates belonged to the HPRO type, had high homology (98.3%~100.0%) and closest relationship with Norway strains. We identified the 9 positive HPRO ISAVs from 491 iced Atlantic salmons (1. 8%). Therefore, we should strengthen the quarantine of iced Atlantic salmons from Norway in case of HPRO ISAV into China.
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January 2017

Toll-like receptors and interferon associated immune factors responses to spring viraemia of carp virus infection in common carp (Cyprinus carpio).

Fish Shellfish Immunol 2016 Aug 1;55:568-76. Epub 2016 Jun 1.

Shenzhen Entry-Exit Inspection and Quarantine Bureau, Shenzhen 518045, China. Electronic address:

Pattern recognition receptor (PRR) toll-like receptors (TLRs), antiviral agent interferon (IFN) and the effector IFN stimulated genes (ISGs) play a fundamental role in the innate immune response against viruses among all vertebrate classes. Common carp is a host for spring viraemia of carp virus (Rhabdovirus carpio, SVCV), which belong to Rhabdoviridae family. The present in-vivo experiment was conducted to investigate the expression of these innate immune factors in early phase as well as during recovery of SVCV infection by real-time quantitative reverse transcriptase polymerase chain reaction. A less lethal SVCV infection was generated in common carp (Cyprinus carpio) and was sampled at 3, 6, 12 h post infection (hpi), 1, 3, 5, 7 and 10 days post infection (dpi). At 3 hpi, the SVCV N gene was detected in all three fish and all three fish showed a relative fold increase of TLR2, TLR3 and TLR7, IFNa1, ISG15 and Vig1. Viral copies rapidly increased at 12 hpi then remained high until 5 dpi. When viral copy numbers were high, a higher expression of immune genes TLR2, TLR3, TLR7, IFNa1, IFNa2, IFNa1S, IFN regulatory factor 3 (IRF3), IRF7, interleukin 1β (IL1β), IL6, IL10, ADAR, ISG15, Mx1, PKR and Vig1 were observed. Viral copies were gradually reduced in 5 to 10 dpi fish, and also the immune response was considerably reduced but remained elevated. A high degree of correlation was observed between immune genes and viral copy number in each of the sampled fish at 12 hpi. The quick and prolonged elevated expression of the immune genes indicates their crucial role in survival of host against SVCV.
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http://dx.doi.org/10.1016/j.fsi.2016.05.043DOI Listing
August 2016

Effect of common carp (Cyprinus carpio) TLR9 overexpression on the expression of downstream interferon-associated immune factor mRNAs in epithelioma papulosum cyprini cells.

Vet Immunol Immunopathol 2016 Feb 23;170:47-53. Epub 2015 Oct 23.

Shenzhen Entry-Exit Inspection and Quarantine Bureau, Shenzhen 518045, China. Electronic address:

Toll-like receptors (TLRs) are a class of pattern recognition receptors (PRRs) that recognize pathogen associated molecular patterns (PAMPs) and play an important role in the antiviral response. To determine the effect of common carp TLR9 (CcTLR9) overexpression on the expression of down-stream interferon associated immune factors in epithelioma papulosum cyprini (EPC) cells, may provide useful information for the further investigation on the anti-virus effect mediated by TLR9 in fish. In this study, we constructed an overexpression vector, pEGFP-N1-CcTLR9, by cloning the CcTLR9 gene and inserting it into an expression vector pEGFP-N1. Both plasmids DNA of pEGFP-N1 and pEGFP-N1-CcTLR9 were transfected into EPC cells, and the expression of IRF3, IRF7, ISG15, Mx1, PKR and Viperin mRNA at 0, 6, 12, 24, 48 and 72h post-transfection were determined by real-time quantitative PCR (Q-PCR). Overexpression of the CcTLR9 gene in EPC cells upregulates the expression of IRF3, IRF7, ISG15, Mx1, PKR, and Viperin mRNA, and this was more significant for Viperin, ISG15, and IRF7, and least significant for PKR. Thus, fish TLR9 activates IRF7 signaling to induce I-IFN secretion and the subsequent upregulation of IFN-stimulated genes.
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http://dx.doi.org/10.1016/j.vetimm.2015.10.006DOI Listing
February 2016

Selection and characterization of single-chain recombinant antibodies against infectious haematopoietic necrosis virus from mouse phage display library.

J Virol Methods 2014 09 18;205:61-7. Epub 2014 Apr 18.

College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China. Electronic address:

Six single-chain fragment variable (scFv) antibodies against infectious haematopoietic necrosis virus (IHNV) were selected from an antibody phage display library by phage display technology. The soluble scFv antibodies showed a molecular weight 32kDa by Western blot. Dot blot analysis revealed that the six scFv antibodies could recognize IHNV. For enzyme linked immunosorbent assay (ELISA), four scFv antibodies (P1A4, P1A12, P1D5 and P3E2) showed cross-reactivity with spring viraemia of carp virus (SVCV). However, none of the six scFv antibodies had cross-reaction with Pike fry rhabdovirus (PFRV), Soft-shelled turtle iridovirus (STIV), viral haemorrhagic septicemia virus (VHSV), or viral nervous necrosis virus (VNNV). Indirect immunofluorescence results showed that all of these scFv antibodies reacted positively with virus in the IHNV-infected cells. These scFv antibodies will be useful in diagnostic test development and pathogenesis studies for IHNV.
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http://dx.doi.org/10.1016/j.jviromet.2014.04.008DOI Listing
September 2014

Development and evaluation of a loop-mediated isothermal amplification assay for diagnosis of Cyprinid herpesvirus 2.

J Virol Methods 2013 Dec 4;194(1-2):206-10. Epub 2013 Sep 4.

Shenzhen Exit and Entry Inspection and Quarantine Bureau, Shenzhen, Guangdong 518001, China.

Goldfish Haematopoietic Necrosis caused by Cyprinid herpesvirus 2 (CyHV-2) is a severe fish disease with high level of mortality. This is the first study on detection of this disease by loop-mediated isothermal amplification (LAMP). A set of six primers targeting terminase gene (accession no. EU349285.1) was determined after a serial of tests. Detection limit was 1.09 × 10(-4)μg/μL, which was superior to conventional PCR and real-time PCR. No cross reaction with 28 other viruses or bacteria commonly found in fish was observed. The application of commercial kit and instrument for the LAMP assay could reduce the risk of cross contamination, which is suitable for detection of infection under field conditions.
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http://dx.doi.org/10.1016/j.jviromet.2013.08.028DOI Listing
December 2013

Selection and characterization of single-chain recombinant antibodies against spring viraemia of carp virus from mouse phage display library.

J Virol Methods 2013 Dec 29;194(1-2):178-84. Epub 2013 Aug 29.

The Key Laboratory of Aquatic Animal Diseases, Shenzhen Exit & Entry Inspection and Quarantine Bureau, Shenzhen 518001, PR China; College of Fisheries, Huazhong Agricultural University, Wuhan 430070, PR China.

Antibody-displaying phage library was selected after three rounds of panning against spring viraemia of carp virus (SVCV) by phage display technology. Eight positive clones which could produce soluble single-chain fragment variable (scFv) antibody induced by isopropyl-beta-d-thiogalactopyranoside (IPTG) were obtained. Dot blot results showed that the eight scFv antibodies could recognize SVCV. The soluble scFv antibodies showed a molecular weight 29 kD by Western blot. All scFv antibodies could recognize SVCV proteins specifically without cross-reaction with other virus proteins by ELISA. Indirect immunofluorescence results showed that all of these scFv antibodies reacted positively with virus in the SVCV-infected cells. These scFv antibodies will be useful tools to establish immunological detection methods for SVCV.
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http://dx.doi.org/10.1016/j.jviromet.2013.08.017DOI Listing
December 2013

Complete sequence of a viral nervous necrosis virus (NNV) isolated from red-spotted grouper (Epinephelus akaara) in China.

Arch Virol 2012 Apr 22;157(4):777-82. Epub 2012 Jan 22.

Shenzhen Exit & Entry Inspection and Quarantine Bureau, 1011 Fuqiang Road, Futian, Shenzhen, 518045, People's Republic of China.

A nodavirus isolated from red-spotted grouper (Epinephelus akaara) larvae in China has been subjected to genome analysis. The full-length genome sequences of RNA1 and RNA2 were determined, and the 5'-non-coding region (NCR) and 3'NCR sequences were determined by 5' rapid amplification of cDNA ends (RACE) and 3'RACE. RNA1 is 3,103 nt in length and contains a 982-amino-acid open reading frame (ORF) encoding protein A with a calculated molecular mass of 110.74 kDa. RNA2 is 1,433 nt long and contains a 338-amino-acid major ORF encoding coat protein with a calculated molecular mass of 37.059 kDa. Multiple alignment and phylogenetic analysis clearly supported including this virus in the species Redspotted grouper nervous necrosis virus, genus Betanodavirus, family Nodaviridae.
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http://dx.doi.org/10.1007/s00705-011-1187-5DOI Listing
April 2012
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