Comparison between specific and multiplex reverse transcription-polymerase chain reaction for detection of hepatitis A virus, poliovirus and rotavirus in experimentally seeded oysters

New approaches in microbial pathogen detection

Viruses are common causes of foodborne outbreaks. Viral diseases have low fatality rates but transmission to humans via food is important due to the high probability of consuming fecally contaminated food or water because of poor food handling. Because of the low infectious doses of some foodborne viruses, there is a need for standardization and the development of new sensitive methods for detecting viruses. The focus is on molecular and non-molecular approaches, and emerging methods for the detection of foodborne viruses. The detection of noroviruses, hepatitis A and E viruses, rotaviruses and adenoviruses will be discussed. The chapter will conclude with insights into future research directions.

Detection of adenoviruses in shellfish by means of conventional-PCR, nested-PCR, and integrated cell culture PCR (ICC/PCR)

We tested three PCR based methodologies to detect adenoviruses associated with cultivated oysters. Conventional-PCR, nested-PCR, and integrated cell culture-PCR (ICC/PCR) were first optimized using oysters seeded with know amounts of Adenovirus serotype 5 (Ad5). The maximum sensitivity for Ad5 detection was determined for each method, and then used to detect natural adenovirus contamination in oysters from three aquiculture farms in Florianopolis, Santa Catarina State, Brazil, over a period of 6 months. The results showed that the nested-PCR was more sensitive (limit of detection: 1.2 PFU/g of tissue) than conventional-PCR and ICC-PCR (limit of detection for both: 1.2 x 10(2)PFU/g of tissue) for detection of Ad5 in oyster extracts. Nested-PCR was able to detect 90% of Ad5 contamination in harvested oyster samples, while conventional-PCR was unable to detect Ad5 in any of the samples. The present work suggests that detection of human adenoviruses can be used as a tool to monitor the presence of human viruses in marine environments where shellfish grow, and that nested-PCR is the method of choice.

Simultaneous detection of HBV and HCV by multiplex PCR normalization

AIM: To design and establish a method of multiplex PCR normalization for simultaneously detecting HBV and HCV.

METHODS: Two pairs of primers with a 20 bp joint sequence were used to amplify the target genes of HBV and HCV by two rounds of amplification. After the two rounds of amplification all the products had the joint sequence. Then the joint sequence was used as primers to finish the last amplification. Finally multiplex PCR was normalized to a single PCR system to eliminate multiplex factor interference. Four kinds of nucleic acid extraction methods were compared and screened. A multiplex PCR normalization method was established and optimized by orthogonal design of 6 key factors. Then twenty serum samples were detected to evaluate the validity and authenticity of this method.

RESULTS: The sensitivity, specificity, diagnostic index and efficiency were 83.3%, 70%, 153.3% and 72.2%, respectively for both HBsAg and anti-HCV positive patients, and were 78.6%, 80%, 258.6% and 79.2%, respectively for HBsAg positive patients, and were 75%, 90%, 165% and 83.3%, respectively for anti-HCV positive patients.

CONCLUSION: The multiplex PCR normalization method shows a broad prospect in simultaneous amplification of multiple genes of different sources. It is practical, correct and authentic, and can be used to prevent and control HBV and HCV.