Limitations of Molecular Biological Techniques for Assessing the Virological Safety of Foods†

1999 ◽  
Vol 62 (6) ◽  
pp. 691-697 ◽  
Author(s):  
GARY P. RICHARDS
Keyword(s):  
Polymerase Chain Reaction ◽  
Environmental Samples ◽  
Hepatitis A ◽  
Enteric Viruses ◽  
Molecular Techniques ◽  
Technical Expertise ◽  
Chain Reaction ◽  
Assay Sensitivity ◽  
Testing Laboratories ◽  
Polymerase Chain

Enteric viruses, including hepatitis A, Norwalk, and Snow Mountain viruses, Hawaii agent, and rotaviruses have been associated with outbreaks of foodborne illness. Classical culturing procedures are available for poliovirus; however, hepatitis A, Norwalk, and many of the other viruses and agents cannot be propagated in cell culture, therefore, molecular biological tools have emerged as a possible means to detect enteric viruses in foods and environmental samples. There are limitations however in the application of polymerase chain reaction and reverse transcription polymerase chain reaction that restrict their usefulness for measuring the virological safety of foods. The most serious limitation is that molecular techniques fail to discriminate between viable and inactivated viruses even though inactivated viruses pose no threat to the consumer and may be present at levels substantially higher than the virulent forms. Other disadvantages include a lack of assay sensitivity and specificity, high assay costs, and a level of technical expertise not available in most food-testing laboratories. Overall, scientific advances in the development of molecular biological tools have outpaced the demonstration of their validity in assessing the virological safety of foods.

Extraction of microsporidial DNA from modified trichrome-stained clinical slides and subsequent species identification using PCR sequencing

Parasitology ◽  
2008 ◽  
Vol 135 (6) ◽  
pp. 701-703 ◽  
Author(s):  
K. S. CHAN ◽  
T. H. KOH
Keyword(s):  
Polymerase Chain Reaction ◽  
Species Identification ◽  
Environmental Samples ◽  
Species Level ◽  
Molecular Techniques ◽  
Chain Reaction ◽  
Clinical Specimens ◽  
Polymerase Chain ◽  
Pcr Conditions ◽  
Hiv Negative

SUMMARYMolecular techniques involving polymerase chain reaction (PCR) and sequencing provide a relatively simple and objective means of identifying microsporidia to species level. We modified previously described methods of DNA extraction and PCR conditions for identification of microsporidia from museum slides, clinical specimens and environmental samples and successfully identifiedVittaforma corneaein 11 out of 13 cases of microsporidial infection from used trichrome-stained slides of corneal scrapings from HIV-negative patients with keratoconjunctivitis.

scholarly journals Polymerase Chain Reaction-Based Methods for Detection of Listeria monocytogenes: Toward Real-Time Screening for Food and Environmental Samples

2002 ◽  
Vol 85 (2) ◽  
pp. 505-515 ◽  
Author(s):  
Dawn M Norton
Keyword(s):  
Polymerase Chain Reaction ◽  
Listeria Monocytogenes ◽  
Real Time ◽  
Environmental Samples ◽  
Messenger Rna ◽  
Nucleic Acid Amplification ◽  
Screening Methods ◽  
Chain Reaction ◽  
Assay Sensitivity ◽  
Polymerase Chain

Abstract A review is presented of nucleic acid amplification-based methodology, specifically polymerase chain reaction (PCR)-based assays, for the detection of Listeria monocytogenes in food and environmental samples. Until recently, developmental challenges including poor sensitivity, due in part to reaction inhibition by components of the sample matrix, and the potential for false-positive reactions have limited routine application of PCR-based screening assays. Commercial assays address these challenges while offering convenient, standardized protocols, a high level of automation, and results within 2 days after the sampling date. Although sample enrichment is necessary to achieve desired detection limits, continued efforts toward template purification will facilitate the development of assays offering real-time, quantitative results. The development of ribonucleic acid (RNA) amplification-based assays may increase in importance, particularly if end-product testing is prioritized by regulatory agencies, as messenger RNA appears to serve as an accurate indicator of cell viability. Further, the increase in target copy number may improve assay sensitivity. PCR-based screening methods offer efficient, reliable results and are ideal for monitoring the presence of L. monocytogenes in foods and in the food processing environment.

Polymerase chain reaction amplification and typing of rotavirus in environmental samples

1995 ◽  
Vol 31 (5-6) ◽  
pp. 371-374 ◽  
Author(s):  
R. Gajardo ◽  
R. M. Pintó ◽  
A. Bosch
Keyword(s):  
Polymerase Chain Reaction ◽  
Environmental Samples ◽  
Polymerase Chain Reaction Amplification ◽  
Rt Pcr ◽  
Chain Reaction ◽  
Pcr Assay ◽  
Group A ◽  
Reaction Amplification ◽  
Stool Specimens ◽  
Polymerase Chain

A reverse transcription polymerase chain reaction (RT-PCR) assay is described that has been developed for the detection and serotyping of group A rotavirus in stool specimens and concentrated and non-concentrated sewage specimens.

Diagnostic Accuracy of a Direct Panfungal Polymerase Chain Reaction Assay Performed on Stained Cytology Slides

2021 ◽  
pp. 030098582199156
Author(s):  
Alexandra N. Myers ◽  
Unity Jeffery ◽  
Zachary G. Seyler ◽  
Sara D. Lawhon ◽  
Aline Rodrigues Hoffmann
Keyword(s):  
Polymerase Chain Reaction ◽  
Diagnostic Accuracy ◽  
Molecular Techniques ◽  
Fungal Culture ◽  
Chain Reaction ◽  
Identification Of Fungi ◽  
Fungal Dna ◽  
Polymerase Chain ◽  
Panfungal Pcr ◽  
Pcr Targeting

Molecular techniques are increasingly being applied to stained cytology slides for the diagnosis of neoplastic and infectious diseases. Such techniques for the identification of fungi from stained cytology slides have not yet been evaluated. This study aimed to assess the diagnostic accuracy of direct (without nucleic acid isolation) panfungal polymerase chain reaction (PCR) followed by sequencing for identification of fungi and oomycetes on stained cytology slides from dogs, cats, horses, and other species. Thirty-six cases were identified with cytologically identifiable fungi/oomycetes and concurrent identification via fungal culture or immunoassay. Twenty-nine controls were identified with no cytologically or histologically visible organisms and a concurrent negative fungal culture. Direct PCR targeting the internal transcribed spacer region followed by sequencing was performed on one cytology slide from each case and control, and the sensitivity and specificity of the assay were calculated. The sensitivity of the panfungal PCR assay performed on stained cytology slides was 67% overall, 73% excluding cases with oomycetes, and 86% when considering only slides with abundant fungi. The specificity was 62%, which was attributed to amplification of fungal DNA from control slides with no visible fungus and negative culture results. Direct panfungal PCR is capable of providing genus- or species-level identification of fungi from stained cytology slides. Given the potential of panfungal PCR to amplify contaminant fungal DNA, this assay should be performed on slides with visible fungi and interpreted in conjunction with morphologic assessment by a clinical pathologist.

scholarly journals Prolonged fecal excretion of hepatitis A virus in adult patients with hepatitis A as determined by polymerase chain reaction

Hepatology ◽  
1996 ◽  
Vol 24 (1) ◽  
pp. 10-13 ◽  
Author(s):  
H Yotsuyanagi ◽  
K Koike ◽  
K Yasuda ◽  
K Moriya ◽  
Y Shintani ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Adult Patients ◽  
Fecal Excretion ◽  
Chain Reaction ◽  
Polymerase Chain

Persistence of Hepatitis A Virus in Oysters†

2003 ◽  
Vol 66 (2) ◽  
pp. 331-334 ◽  
Author(s):  
DAVID H. KINGSLEY ◽  
GARY P. RICHARDS
Keyword(s):  
Polymerase Chain Reaction ◽  
Crassostrea Virginica ◽  
Reverse Transcription ◽  
Hepatitis A ◽  
Infectious Virus ◽  
Hepatitis A Virus ◽  
Complete Removal ◽  
Chain Reaction ◽  
Daily Feeding ◽  
Polymerase Chain

We investigated the ability of hepatitis A virus (HAV) to persist for up to 6 weeks in Eastern oysters (Crassostrea virginica). Viral RNA was detected by reverse transcription–polymerase chain reaction 6 weeks after 16 h of exposure to 90,000 PFU (180 PFU/ml of seawater) of HAV. Assaying for infectious virus in oysters that received a daily feeding of phytoplankton recovered 3,800, 650, and 500 PFU of HAV 1, 2, and 3 weeks after contamination with 90,000 PFU of HAV, respectively. However, no infectious HAV was isolated from oysters 4, 5, or 6 weeks after contamination. These results support the position that shellfish depuration is insufficient for the complete removal of infectious viruses. Extended relay times (in excess of 4 weeks) may be required to produce virologically safe shellfish.

scholarly journals Molecular diagnosis and biochemical studies of tick-borne diseases (anaplasmosis and babesiosis) in Aberdeen Angus Cattle in New Valley, Egypt

2020 ◽  
Vol 13 (9) ◽  
pp. 1884-1891
Author(s):  
Nani Nasreldin ◽  
Rania M. Ewida ◽  
Hatem Hamdon ◽  
Yasser F. Elnaker
Keyword(s):  
Oxidative Stress ◽  
Polymerase Chain Reaction ◽  
Molecular Techniques ◽  
Babesia Bovis ◽  
Blood Parasites ◽  
Chain Reaction ◽  
Infected Female ◽  
Angus Cattle ◽  
Polymerase Chain ◽  
Female Cattle

Background and Aim: Anaplasmosis and babesiosis are tick-borne diseases that threaten livestock production with subsequent considerable economic losses. This study was conducted to diagnose Anaplasma and Babesia infection using molecular techniques in imported Aberdeen Angus cattle imported from Uruguay to El-Kharga Oasis in New Valley, Egypt, and to investigate the effects of disease on some serum biochemical and oxidative stress parameters. Materials and Methods: Blood samples were collected from 31 cattle, 21 diseased and ten apparently normal, of varying ages and sex. The blood was used for the preparation of blood smears, polymerase chain reaction assay, and separation of serum for biochemical investigation. The experimental production farm at the Faculty of Agriculture, New Valley University, was infested with ticks and variable clinical manifestations during the period from December 2017 to March 2018. One calf died of a suspected blood parasite infection. Results: The blood film examination revealed infection by blood parasites in 21 samples. Anaplasma marginale and Babesia bovis were identified in 12 and 14 samples, respectively. A total of 14 samples were examined by polymerase chain reaction (PCR) to make these identifications. Biochemical parameters showed significantly elevated serum alanine aminotransferase, aspartate aminotransferase, total bilirubin (T. Bil), and urea in blood from parasite-infected female cattle and male calves compared with controls. Increased serum total protein, globulin, and creatinine were recorded only in infected female cattle. The blood glucose level was significantly decreased in infected female cattle and male calves compared with controls. Furthermore, albumin and albumin/globulin ratio was significantly reduced in the infected female cattle. Oxidative stress profiles of infected animals showed a significant increase in serum nitric oxide and malondialdehyde, and both total antioxidant capacity and reduced glutathione (GSH) were significantly reduced in comparison with control animals. Conclusion: The incidence of A. marginale and B. bovis infection is high in imported Aberdeen Angus cattle in New Valley Province. PCR methods provide a short-term assessment of disease. An extensive epidemiological survey, employing serology together with molecular genetic methods, monitoring of abundance and distribution of tick vectors, availability of vaccination programs, and tracking of animal transport is also needed for control of blood parasites.

scholarly journals Occurrence of virulent multidrug-resistantEnterococcus faecalisandEnterococcus faeciumin the pigs, farmers and farm environments in Malaysia

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5353 ◽  
Author(s):  
Shiang Chiet Tan ◽  
Chun Wie Chong ◽  
Cindy Shuan Ju Teh ◽  
Peck Toung Ooi ◽  
Kwai Lin Thong
Keyword(s):  
Polymerase Chain Reaction ◽  
Antibiotic Resistance ◽  
Environmental Factors ◽  
Environmental Samples ◽  
Virulence Genes ◽  
Multidrug Resistant ◽  
Peninsular Malaysia ◽  
Chain Reaction ◽  
Swine Farms ◽  
Polymerase Chain

BackgroundEnterococcus faecalisandEnterococcus faeciumare ubiquitous opportunistic pathogens found in the guts of humans and farmed animals. This study aimed to determine the occurrence, antimicrobial resistance, virulence, biofilm-forming ability and genotypes ofE. faecalisandE. faeciumfrom swine farms. Correlations between the genotypes, virulotypes, antibiotic resistance, and the environmental factors such as locality of farms and farm hygiene practice were explored.MethodsE. faecalisandE. faeciumstrains were isolated from the oral, rectal and fecal samples of 140 pigs; nasal, urine and fecal samples of 34 farmers working in the farms and 42 environmental samples collected from seven swine farms located in Peninsular Malaysia. Antibiotic susceptibility test was performed using the disk diffusion method, and the antibiotic resistance and virulence genes were detected by Polymerase Chain Reaction. Repetitive Extragenic Palindromic-Polymerase Chain Reaction and Pulsed-Field Gel Electrophoresis were performed to determine the clonality of the strains. Crosstab/Chi-square test and DistLM statistical analyses methods were used to determine the correlations between the genotypes, virulence factors, antibiotic resistance, and the environmental factors.ResultsA total of 211E. faecalisand 42E. faeciumwere recovered from 140 pigs, 34 farmers and 42 environmental samples collected from seven swine farms in Peninsular Malaysia. Ninety-eight percent of the strains were multidrug-resistant (resistant to chloramphenicol, tetracycline, ciprofloxacin and erythromycin). Fifty-two percent of the strains formed biofilms. Virulence genesefa, asaI, gelE,esp,cylandacegenes were detected. Virulence genesefaandasaI were most prevalent inE. faecalis(90%) andE. faecium(43%), respectively. Cluster analyses based on REP-PCR and PFGE showed the strains were genetically diverse. Overall, the strains isolated from pigs and farmers were distinct, except for three highly similar strains found in pigs and farmers. The strains were regional- and host-specific.DiscussionThis study revealed alarming high frequencies of multidrug-resistant enterococci in pigs and swine farmers. The presence of resistance and virulence genes and the ability to form biofilm further enhance the persistence and pathogenicity of the strains. Although the overall clonality of the strains were regionals and host-specific, strains with high similarity were found in different hosts. This study reiterates a need of a more stringent regulation to ensure the proper use of antibiotics in swine husbandry to reduce the wide spread of multidrug-resistant strains.

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