Detection of Human polyomavirus 2 (HPyV2) in oyster samples in northern Brazil

Comparative evaluation of specimen type and processing conditions for studying oyster microbiomes

Metagenomic sequencing is increasingly being employed to understand the assemblage and dynamics of the oyster microbiome. Specimen collection and processing steps can impact the resultant microbiome composition and introduce bias. To investigate this systematically, a total of 54 farmed oysters were collected from Chesapeake Bay between May and September 2019. Six different specimen types and processing methods were evaluated for microbial community composition using shotgun metagenomics, namely fresh oyster homogenate (FOH), oyster homogenate after simulated temperature abuse (AOH), Luria broth-enriched oyster homogenate (EOH), dissected stomach homogenate (DSH), hemolymph (HLM), and stomach-gut content (SGC). In general, DSH, EOH, and FOH yielded the highest DNA concentration, while EOH had the highest microbial reads, followed by DSH, HLM, and FOH. HLM produced the highest bacterial species alpha diversity, followed by AOH, EOH, and SGC. Although alpha diversities did not differ significantly, beta-diversity measurements showed significant dissimilarity among methods (p < 0.05) indicating that the specimen types and processing steps do play an important role in representing the composition of the bacterial community. Bacterial species that had the highest log mean abundance included Cyanobium sp. PCC 7001 in FOH, Vibrio vulnificus in AOH, EOH, and DSH, and lastly Synechococcus sp. CB0205 in the DSH, HML, and SGC samples. EOH displayed higher bacterial hits, distinct microbial composition, and higher values of bacterial, phages, and antimicrobial resistance gene reads. Therefore, if studying the overall oyster microbial community, prioritizing optimum specimen collection and processing methods that align with the overall goal of the study is recommended.

Assessment of Microbiological Quality of Fresh Vegetables and Oysters Produced in Buenos Aires Province, Argentina

Fresh vegetables and shellfish are prone to microbial contamination through irrigation or breeding with sewage-polluted waters, as well as by infected food handlers. In this work, we studied the presence of human and bovine polyomaviruses and human norovirus in fresh lettuces, strawberries and oysters produced in Buenos Aires province, Argentina. In oysters, we also investigated F-specific RNA bacteriophages, indicator Escherichia coli (E. coli) and pathogen bacteria of concern (Salmonella spp., Vibrio spp.). Within vegetables, we found viral contamination of human origin given the presence of human-associated polyomaviruses -MCPyV, HPyV6, JCPyV, and SV40- in lettuce and strawberry samples (16 and 10%, respectively), probably coming from irrigation waters and food handling. Among oysters, human (MCPyV, 4.2%) and bovine (BPyV1, 8.4%) polyomaviruses were detected even with low counts of E. coli. Bacteriophages (n = 3) and Salmonella spp. (n = 1) were also found, while Vibrio spp. was not detected. These results may indicate that the contamination in oysters comes from human and animal excreta, probably present in breeding waters. Norovirus was not detected in any food sample. To our knowledge, this is the first description of SV40 in lettuces and MCPyV and BPyV1 in oysters. The detection of different viral contaminants encourages further studies to evaluate the need for including viral indicators in microbiological standards. The identification of possible sources and routes of contamination using viral markers during routine microbiological controls, such as the polyomaviruses used in this work, would be useful to focus attention on the most hazardous stages of the food production chain.

Induction of Brain Tumors by the Archetype Strain of Human Neurotropic JCPyV in a Transgenic Mouse Model

JC Virus (JCPyV), a member of the Polyomaviridiæ family, is a human neurotropic virus with world-wide distribution. JCPyV is the established opportunistic infectious agent of progressive multifocal leukoencephalopathy, a fatal demyelinating disease, which results from the cytolytic infection of oligodendrocytes. Mutations in the regulatory region of JCPyV determine the different viral strains. Mad-1 the strain associated with PML contains two 98 base pair repeats, whereas the archetype strain (CY), which is the transmissible form of JCPyV, contains only one 98 tandem with two insertions of 62 and 23 base pairs respectively. The oncogenicity of JCPyV has been suspected since direct inoculation into the brain of rodents and primates resulted in the development of brain tumors and has been attributed to the viral protein, T-Antigen. To further understand the oncogenicity of JCPyV, a transgenic mouse colony containing the early region of the archetype strain (CY), under the regulation of its own promoter was generated. These transgenic animals developed tumors of neural crest origin, including: primitive neuroectodermal tumors, medulloblastomas, adrenal neuroblastomas, pituitary tumors, malignant peripheral nerve sheath tumors, and glioblastomas. Neoplastic cells from all different phenotypes express T-Antigen. The close parallels between the tumors developed by these transgenic animals and human CNS tumors make this animal model an excellent tool for the study of viral oncogenesis.