Construction of an internal standard used in RT nested PCR for Borna Disease Virus RNA detection in biological samples

Development of SYBR Green real-time PCR and nested RT-PCR for the detection of Potato Mop-top Virus (PMTV) and viral surveys in Progeny tubers derived from PMTV infected Potato tubers

In this study, a new SYBR Green qPCR (qRT-PCR) and a nested RT-PCR (nRT-PCR) were developed to detect Potato mop-top virus (PMTV) in potato tuber tissues. The SYBR Green qRT-PCR and nRT-PCR assays were approximately 10⁴- and 10³- fold more sensitive than the conventional RT-PCR assay. The progeny tubers derived from PMTV-infected potato tubers were tested by conventional RT-PCR, SYBR Green qRT-PCR and nRT-PCR assays. Of the 17 samples, 9 (52.9%) were positive for PMTV by conventional RT-PCR, 11 (64.7%) were positive by nRT-PCR, and 17 (100%) were positive by SYBR Green qRT-PCR. Compared to nRT-PCR, SYBR Green qRT-PCR was showed to be more sensitive. The progeny plants exhibited foliar symptoms including chlorosis and reduction in leaf size when the PMTV-positive tubers were planted in a growth chamber at 20-22 °C. These findings suggest that PMTV has been passed on to the progeny plants and tubers.

Simple procedures to obtain exogenous internal controls for use in RT-PCR detection of bovine pestiviruses

Pestiviruses are ubiquitous pathogens of cattle and frequent adventitious viruses in biologicals. Furthermore, it has been suggested that these agents might be related to infantile gastroenteritis and microencephaly. Since the virus is highly prevalent in fetal bovine serum, the risk of contamination is high in most laboratories. Thus, the implementation of detection methods in all laboratories is of worth. Despite continuous surveillance, these agents have been detected in cell lines, fetal bovine serum, live and inactivated animal and human vaccines and interferon for human use. In this report, DNA and RNA internal controls (ICs) which can be implemented in laboratories with minimal equipment are described. The developed standards can be added before RNA purification, allowing to monitor all steps of the protocol (viral RNA extraction, reverse transcription and cDNA amplification). It is shown that inhibitory effects that could lead to decreased sensitivity can be minimized by controlling the amount of mimic molecules added to the samples. A method to avoid the problem of DNA traces present in in vitro transcribed RNA preparations is provided.

Borna disease virus RNA in immunocompromised patients in southwestern France

Borna disease virus (BDV) is a neurotropic RNA virus with a wide host range. Human infections, although controversial, have been described in Europe, Asia, and the United States. The present study investigated the existence of BDV infections in immunocompromised human beings, namely, 82 human immunodeficiency virus (HIV)-infected and 80 therapeutically immunosuppressed patients. BDV p40 RNAs were detected in peripheral white blood cells with reverse transcription-nested PCR and hybridization in, respectively, 11 (13.41%) and 1 (1.25%) of the two groups of patients. BDV p24 RNAs were identified in only one of those. BDV RNA was detected in the absence of any neuropsychiatrical illness, suggesting that BDV infections may occur in asymptomatic carriers. The severity and particularity of cellular immunosuppression could explain the significantly increased detection of BDV RNA in HIV-infected patients.

Development of a RT-nested PCR test detecting pigeon Paramyxovirus-1 directly from organs of infected animals

A RT-nested PCR that amplifies part of the conserved nucleoprotein gene of avian Paramyxovirus type 1 is described. The technique allowed the detection of pigeon Paramyxovirus type 1 (pPMV-1) virus directly from a wide range of infected chicken and pigeon organs, and should be able to detect typical Newcastle disease viruses too. Compared with the reference method, the developed RT-nested PCR was found more sensitive, as it was able to detect virus genome in infected pigeon organs at late stage of infection, when virus isolation failed. Such a molecular technique represents an alternative method of diagnosis for research purposes on pPMV-1 variants, for example to study pathogenesis aspects of the infection or to assess the efficacy of vaccines.

Evidence of Borna disease virus genome detection in French domestic animals and in foxes (Vulpes vulpes)

Borna disease virus (BDV) is an enveloped, non-segmented negative-stranded RNA virus which belongs to the Bornaviridae family. BDV is an aetiological agent of encephalitis in horses, sheep and several other vertebrate species. In order to extend our knowledge about the presence of BDV in France, a study based on BDV RNA detection by RT-nested-PCR was done with 196 animal tissues: 171 brain samples collected from different animal species (75 horses, 59 foxes, 31 cattle, 4 dogs, 1 sheep, 1 roe deer) and 25 horse blood samples. An RNA internal standard molecule was constructed and was co-amplified with the test template. This study reports the first detection of BDV RNA in France in 10 brain samples collected from horses, foxes and cattle, and from 14 horse blood samples. Detection of the BDV genome in the brains of six red foxes is the first evidence of BDV infection in this species.