A systematic review of FTA cards® as a tool for viral RNA preservation in fieldwork: Are they safe and effective?

BackgroundDetection and characterization of viral RNA pathogens from fieldwork are challenging due to the instability of the RNA molecule. FTA cards® have proved useful for sample storage and latter identification of pathogens with importance for agricultural, animal and human health: however, for optimal handling, processing, and biosafety measures are not well-established. ObjectiveThis systematic review aims to summarize the reported effectiveness of FTA cards® for storage and transport of viral RNA, as well as the conditions for their handling and use in downstream processes. Finally, the biosafety measures required to protect researchers and clinical lab workers are considered. MethodsWe performed a systematic review following the PRISMA statement. We searched MEDLINE (PubMed), Scopus and Web of Science using the keywords "FTA cards" AND "RNA". Articles were screened by title and abstract, and after examination of inclusion and exclusion criteria, relevant information was extracted. The quality of the studies was assessed, and the evidence was qualitatively summarized. ResultsA total of 175 records were retrieved, and 11 additional documents were found by checking references of the eligible articles. A total of 47 articles were included. Samples from animals accounted for 38.3% of the publications, which identified viruses that cause disease in poultry, wild birds, suids, or bovids. Three different methods for RNA extraction were reported. Other factors that vary across reports include the size of RNA amplicon, storage temperature, and duration of storage. Only fourteen articles tested the inactivation of the virus on the FTA card®, and in one case, the virus remained infective. ConclusionFTA cards® could be a suitable option for RNA virus storage and transport for fieldwork in areas where proper conditions for RNA preservation are difficult to achieve. Three different protocols have been used for RNA detection from this matrix. Biospecimens in the form of dried blood spots should be considered potentially infectious unless specifically treated to inactivate viral pathogens.

Human papillomavirus in upper digestive tract tumors from three countries.

AIM: To clarify human papillomavirus (HPV) involvement in carcinogenesis of the upper digestive tract of virological and pathological analyses. METHODS: The present study examined the presence of HPV in squamous cell carcinomas of the oral cavity (n = 71), and esophagus (n = 166) collected from Japan, Pakistan and Colombia, with different HPV exposure risk and genetic backgrounds. The viral load and physical status of HPV16 and HPV16-E6 variants were examined. Comparison of p53 and p16(INK4a) expression in HPV-positive and HPV-negative cases was also made. RESULTS: HPV16 was found in 39 (55%) oral carcinomas (OCs) and 24 (14%) esophageal carcinomas (ECs). This site-specific difference in HPV detection between OCs and ECs was statistically significant (P < 0.001). There was a significant difference in the geographical distribution of HPV16-E6 variants. Multiple infections of different HPV types were found in 13 ECs, but multiple infections were not found in OCs. This difference was statistically significant (P = 0.001). The geometric means (95% confidence interval) of HPV16 viral load in OCs and ECs were 0.06 (0.02-0.18) and 0.12 (0.05-0.27) copies per cell, respectively. The expression of p16(INK4a) proteins was increased by the presence of HPV in ECs (53% and 33% in HPV-positive and -negative ECs, respectively; P = 0.036), and the high-risk type of the HPV genome was not detected in surrounding normal esophageal mucosa of HPV-positive ECs. CONCLUSION: Based on our results, we cannot deny the possibility of HPV16 involvement in the carcinogenesis of the esophagus.

Plasmodium vivax: Dimorphic DNA Sequences from the MSP-1 Gene Code for Regions That Are Immunogenic in Natural Infections

The merozoite surface protein 1 gene of Plasmodium vivax (PvMSP-1) is becoming a solid genetic marker for studying the polymophism of natural parasite populations from this prevalent human malaria. Indeed a conserved and a variant PvMSP-1 gene segment have been amplified from total genomic parasite DNA obtained from isolates representing seven countries and three continents. Interestingly, the variant PvMSP-1 gene segment contains two highly conserved parental allele forms capable of limited genetic exchange the sexual stage in the mosquito vector. This variant PvMSP-1 gene segment was amplified from 18 Colombiam isolates to try determine whether the same two parental allele forms were also presented in this geographical area. Southern blot and DNA sequencing analyses confirmed their existence among the Colombian isolates. Moreover, expression of these two allele forms a recombinant protein allowed us to demonstrate for the time that this PvMSP-1 gene segment codes for amino acid that are exposed on the surface of P. vivax schizonts and that are immunogenic in natural infections.