Infectious Agents in Bovine Red Meat and Milk and Their Potential Role in Cancer and Other Chronic Diseases

Outer membrane vesicles of Acinetobacter baumannii DS002 carry circular DNA similar to bovine meat and milk factors (BMMFs) and SPHINX 2.36 and probably play a role in interdomain lateral gene transfer

The discovery of Replication Competent Circular DNA molecules in mammalian cells and tissues is being linked to debilitating diseases, such as multiple sclerosis (MS), bovine spongiform encephalopathy (BSE), and colorectal cancer (CRC). These circular DNA molecules, otherwise known as bovine meat and milk factors (BMMFs) and Slow Progressive Hidden INfections of variable (X) latency (SPHINX), bear significant (80%) sequence similarity with the plasmids of Acinetobacter baumannii strains. Nanostructures, such as bacterial outer membrane vesicles (OMVs) serve as vehicles for transporting biomolecular cargo and have the potential to facilitate interkingdom lateral mobility of DNA. Strengthening the proposed hypothesis, this study demonstrates that OMVs derived from A. baumannii DS002 carrying four plasmids and genome (pTS236) of phage, AbDs1, successfully reached different parts of the body, including the central nervous system, following the injection of fluorescein isothiocyanate (FITC)-labeled OMVs into experimental mice. Out of the four OMV-associated plasmids, three (pTS4586, pTS9900, and pTS134338) were identified within the lumen, and the fourth one (pTS11291) was found on the surface of OMVs. In addition to the indigenous plasmids, the phage-encoded protein, Orf96, anchored on the surface of the OMVs by establishing a strong interaction with the OMV-associated porin, OmpA. Intriguingly, a subset of labeled OMVs, when incubated with Neuro2A cells, translocated across the membrane and reached to the cytoplasmic space of the cells. Collectively, the experimental evidence presented herein underscores the promising potential of OMVs as vehicles for delivering molecular cargo containing plasmids and phage genomes to diverse mammalian tissues and cells.

IMPORTANCE

Several independent studies have demonstrated the existence of replication competent circular DNA molecules of bacterial and viral origin in mammalian cells and tissues. However, studies about their origin and lateral mobility to mammalian cells are scarce. Our work describes the existence of circular DNA, similar to that of DNA molecules identified in mammalian cells, OMVs derived from soil isolate of A. baumannii DS002. Furthermore, the work also provides visual evidence that demonstrates the passage of labeled OMVs to different organs of experimental mice within hours after intravenously administering OMVs into experimental mice. Some of the labeled OMVs have even crossed the membrane of Neuro2A, suggesting the existence of interkingdom horizontal mobility between bacteria and mammals.

Proliferative arrest induces neuron differentiation and innate immune responses in control and Creutzfeldt-Jakob Disease agent infected rat septal neurons

Rat post-mitotic septal (SEP) neurons, engineered to conditionally proliferate at 33°C, differentiate when arrested at 37.5°C and can be maintained for weeks without cytotoxic effects. Nine independent cDNA libraries were made to follow arrest-induced neural differentiation and innate immune responses in normal (Nl) uninfected and CJ agent infected SEP cells. Proliferating Nl versus latently infected (CJ-) cells showed few RNA-seq differences. However arrest induced major changes. Normal cells displayed a plethora of anti-proliferative transcripts. Additionally, known neuron differentiation transcripts, e.g., Agtr2, Neuregulin-1, GDF6, SFRP4 and Prnp were upregulated. These Nl neurons also displayed many activated IFN innate immune genes, e.g., OAS1, RTP4, ISG20, GTB4, CD80 and cytokines, complement, and clusterin (CLU) that binds to misfolded proteins. In contrast, arrested highly infectious CJ+ cells (10 logs/gm) downregulated many replication controls. Furthermore, arrested CJ+ cells suppressed neuronal differentiation transcripts, including Prnp which is essential for CJ agent infection. CJ+ cells also enhanced IFN stimulated pathways, and analysis of the 342 CJ+ unique transcripts revealed additional innate immune and anti-viral-linked transcripts, e.g., Il17, ISG15, and RSAD2 (viperin). These data show: 1) innate immune transcripts are produced by normal neurons during differentiation; 2) CJ infection can enhance and expand anti-viral responses; 3) latent CJ infection epigenetically imprints many proliferative pathways to thwart complete arrest. CJ+ brain microglia, white blood cells and intestinal myeloid cells with shared transcripts may be stimulated to educe latent CJD infections that can be clinically silent for >30 years.

Evaluation of the prevalence of bovine leukemia virus DNA in peripheral blood mononuclear cells of multiple sclerosis patients

Multiple sclerosis (MS) is an immune system-mediated neurodegenerative disease. Recent studies suggest that viral agents, especially the Epstein Barr virus (EBV), are etiological agents for MS. The roles of other viruses in MS have been investigated. Studies have shown an increase in the level of antibodies against bovine leukemia virus (BLV) in patients with MS. In this regard, our study aimed to examine the presence of BLV DNA in peripheral blood mononuclear cells (PBMCs) of MS patients in Iran. In this cross-sectional study, the presence of BLV in 109 Iranian MS patients and 60 healthy controls was evaluated. The isolated PBMCs were used for DNA extraction and PCR, using specific primers for two distinct genes. The mean age of the participants was 39 ± 9.5 years, and 27 (24.77%) of them were male. Clinical evaluation of these patients showed the most frequent MS type to be relapsing-remitting MS (RRMS) (71; 65.14%). BLV evaluation did not show any BLV DNA presence in the PBMCs of individuals in either the MS or healthy control groups. Therefore, our study showed no evidence of BLV infection in Iranian MS patients.

First Insights into the Occurrence of Circular Single-Stranded DNA Genomes in Asian and African Cattle

Circular replicase-encoding single-stranded (CRESS) DNA viruses and other circular DNA agents are increasingly found in various samples and animals. A specific class of these agents-termed bovine meat and milk factors (BMMF)-has been supposed to act as a factor in indirect carcinogenesis in humans. Initial observations attributed the BMMF to European cattle breeds and foodstuffs produced thereof. In the present study, blood and fecal samples from African and Asian cattle were examined. BMMF molecules and genomoviruses were detected in all bovids under study. The majority (79%) of the 29 circular elements could be assigned to BMMF groups 1 and 2, whereas CRESS viruses of the family Genomoviridae accounted for the smaller part (21%). Two genomoviruses belong to the genus Gemykibivirus and one to the genus Gemykrogvirus. The remaining three might be considered as novel species within the genus Gemycircularvirus. The majority of all isolated molecules originated from fecal samples, whereas only three derived from blood. The results from this study expand our knowledge on the diversity and presence of circular DNA in different ruminants that serve for food production in many countries over the world.

A Novel Circular Rep-Encoding Single-Stranded DNA from Holstein Calves

A novel, circular DNA molecule was identified in the serum of 4-week-old Holstein calves via Illumina sequencing. Comparisons with the NCBI nucleotide data bank indicate that the sequence is unique. The circle contains one predicted open reading frame (ORF), whose translated protein sequence shows high similarity to bacterial Rep proteins.

The Roles of the Virome in Cancer

Viral infections as well as changes in the composition of the intestinal microbiota and virome have been linked to cancer. Moreover, the success of cancer immunotherapy with checkpoint inhibitors has been correlated with the intestinal microbial composition of patients. The transfer of feces-which contain mainly bacteria and their viruses (phages)-from immunotherapy responders to non-responders, known as fecal microbiota transplantation (FMT), has been shown to be able to convert some non-responders to responders. Since phages may also increase the response to immunotherapy, for example by inducing T cells cross-reacting with cancer antigens, modulating phage populations may provide a new avenue to improve immunotherapy responsiveness. In this review, we summarize the current knowledge on the human virome and its links to cancer, and discuss the potential utility of bacteriophages in increasing the responder rate for cancer immunotherapy.

Bovine Meat and Milk Factors (BMMFs): Their Proposed Role in Common Human Cancers and Type 2 Diabetes Mellitus

Simple Summary

This manuscript emphasizes the mechanistic differences of infectious agents contributing to human cancers either by “direct” or “indirect” interactions. The epidemiology of cancers linked to direct carcinogens differs (e.g., response to immunosuppression) from those cancers linked with indirect infectious interactions. We discuss their role in colon, breast, and prostate cancers and type II diabetes mellitus. A brief discussion covers the potential role of BMMF (bovine meat and milk factor) infections in acute myeloid leukemia.

Abstract

Exemplified by infections with bovine meat and milk factors (BMMFs), this manuscript emphasizes the different mechanistic aspects of infectious agents contributing to human cancers by “direct” or “indirect” interactions. The epidemiology of cancers linked to direct carcinogens (e.g., response to immunosuppression) differs from those cancers linked with indirect infectious interactions. Cancers induced by direct infectious carcinogens commonly increase under immunosuppression, whereas the cancer risk by indirect carcinogens is reduced. This influences their responses to preventive and therapeutic interferences. In addition, we discuss their role in colon, breast and prostate cancers and type II diabetes mellitus. A brief discussion covers the potential role of BMMF infections in acute myeloid leukemia.

Collaborative Equilibrium Coupling of Catalytic DNA Nanostructures Enables Programmable Detection of SARS-CoV-2

Accessible and adaptable nucleic acid diagnostics remains a critical challenge in managing the evolving COVID-19 pandemic. Here, an integrated molecular nanotechnology that enables direct and programmable detection of SARS-CoV-2 RNA targets in native patient specimens is reported. Termed synergistic coupling of responsive equilibrium in enzymatic network (SCREEN), the technology leverages tunable, catalytic molecular nanostructures to establish an interconnected, collaborative architecture. SCREEN mimics the extraordinary organization and functionality of cellular signaling cascades. Through programmable enzyme-DNA nanostructures, SCREEN activates upon interaction with different RNA targets to initiate multi-enzyme catalysis; through system-wide favorable equilibrium shifting, SCREEN directly transduces a single target binding into an amplified electrical signal. To establish collaborative equilibrium coupling in the architecture, a computational model that simulates all reactions to predict overall performance and optimize assay configuration is developed. The developed platform achieves direct and sensitive RNA detection (approaching single-copy detection), fast response (assay reaction is completed within 30 min at room temperature), and robust programmability (across different genetic loci of SARS-CoV-2). When clinically evaluated, the technology demonstrates robust and direct detection in clinical swab lysates to accurately diagnose COVID-19 patients.

Lamprey Immune Protein Mediates Apoptosis of Lung Cancer Cells Via the Endoplasmic Reticulum Stress Signaling Pathway

Lamprey immune protein (LIP), a novel protein derived from the Lampetra japonica, has been shown to exert efficient tumoricidal actions without concomitant damage to healthy cells. Our study aimed to ascertain the mechanisms by which LIP inhibits lung cancer cells, thus delineating potential innovative therapeutic strategies. LIP expression in lung cancer cells was evaluated by western blotting and immunohistochemistry. Functional assays, such as high-content imaging, 3D-structured illumination microscopy (3D-SIM) imaging, flow cytometry, and confocal laser scanning microscopy, were performed to examine the proliferation and lung cancer cell apoptosis. Tumor xenograft assays were performed using an in vivo imaging system. We observed that LIP induces the decomposition of certain lung cancer cell membranes by destroying organelles such as the microtubules, mitochondria, and endoplasmic reticulum (ER), in addition to causing leakage of cytoplasm, making the maintenance of homeostasis difficult. We also demonstrated that LIP activates the ER stress pathway, which mediates lung cancer cell apoptosis by producing reactive oxygen species (ROS). In addition, injection of LIP significantly retarded the tumor growth rate in nude mice. Taken together, these data revealed a role of LIP in the regulation of lung cancer cell apoptosis via control of the ER stress signaling pathway, thus revealing its possible application in lung cancer treatment.

Circular Rep-Encoding Single-Stranded DNA Sequences in Milk from Water Buffaloes (Bubalus arnee f. bubalis)

Isolation and characterization of circular replicase-encoding single-stranded (ss) DNA from animal, plant and environmental samples are rapidly evolving in virology. We detected 21 circular DNA elements, including one genomoviral sequence, in individual milk samples from domesticated Asian water buffaloes (Bubalus arnee f. bubalis). Most of the obtained genomes are related to Sphinx 1.76 and Sphinx 2.36 sequences and share a high degree of similarity to recently published circular DNAs—named BMMF (bovine meat and milk factors)—that have been isolated from commercial milk, as well as from bovine serum. Characteristic features such as rep genes, tandem repeats and inverted repeats were detected. These BMMF have recently been found to be present in taurine-type dairy cattle breeds descending from the aurochs (Bos primigenius). Importantly, the occurrence of BMMF has been linked to the higher incidence of colorectal and breast cancer in North America and Western Europe compared with Asia. This is the first report of circular ssDNA detected in milk from the domesticated form of the wild Asian water buffalo (B. arnee) belonging to the subfamily Bovinae. This novelty should be taken into account in view of the above-mentioned cancer hypothesis.

Dairy consumption and hepatocellular carcinoma risk

This review provides epidemiological and translational evidence for milk and dairy intake as critical risk factors in the pathogenesis of hepatocellular carcinoma (HCC). Large epidemiological studies in the United States and Europe identified total dairy, milk and butter intake with the exception of yogurt as independent risk factors of HCC. Enhanced activity of mechanistic target of rapamycin complex 1 (mTORC1) is a hallmark of HCC promoted by hepatitis B virus (HBV) and hepatitis C virus (HCV). mTORC1 is also activated by milk protein-induced synthesis of hepatic insulin-like growth factor 1 (IGF-1) and branched-chain amino acids (BCAAs), abundant constituents of milk proteins. Over the last decades, annual milk protein-derived BCAA intake increased 3 to 5 times in Western countries. In synergy with HBV- and HCV-induced secretion of hepatocyte-derived exosomes enriched in microRNA-21 (miR-21) and miR-155, exosomes of pasteurized milk as well deliver these oncogenic miRs to the human liver. Thus, milk exosomes operate in a comparable fashion to HBV- or HCV- induced exosomes. Milk-derived miRs synergistically enhance IGF-1-AKT-mTORC1 signaling and promote mTORC1-dependent translation, a meaningful mechanism during the postnatal growth phase, but a long-term adverse effect promoting the development of HCC. Both, dietary BCAA abundance combined with oncogenic milk exosome exposure persistently overstimulate hepatic mTORC1. Chronic alcohol consumption as well as type 2 diabetes mellitus (T2DM), two HCC-related conditions, increase BCAA plasma levels. In HCC, mTORC1 is further hyperactivated due to RAB1 mutations as well as impaired hepatic BCAA catabolism, a metabolic hallmark of T2DM. The potential HCC-preventive effect of yogurt may be caused by lactobacilli-mediated degradation of BCAAs, inhibition of branched-chain α-ketoacid dehydrogenase kinase via production of intestinal medium-chain fatty acids as well as degradation of milk exosomes including their oncogenic miRs. A restriction of total animal protein intake realized by a vegetable-based diet is recommended for the prevention of HCC.

Meat, fruit, and vegetable consumption in sub-Saharan Africa: a systematic review and meta-regression analysis

CONTEXT

The dietary choices people make affect personal health and have consequences for the environment, both of which have serious implications for the 2030 Sustainable Development Agenda. In global reviews, the literature on meat, fruit, and vegetable consumption in sub-Saharan Africa (SSA) is limited.

OBJECTIVE

This systematic review set out to quantify meat, fruit, and vegetable consumption in SSA populations and to answer the following question: How much meat, fruit, and/or vegetables are being consumed daily by which individuals in SSA over the years?

DATA SOURCES

Following the PRISMA guidelines, the authors systematically searched the MEDLINE, EMBASE, ASSIA CINAHL, Web of Science, POPLINE, and Google Scholar databases to identify 47 (out of 5922 search results) studies reporting meat, fruit, and/or vegetable consumption in SSA populations.

DATA EXTRACTION

Three independent investigators extracted data on year of data collection, study country, study population and geographical context, and population intake of meat, fruit, and/or vegetables.

DATA ANALYSIS

Using STATA SE version 15 software, random-effects meta-regression analyses were used to test the effect of year of data collection and method of data collection on population meat, fruit, and vegetable consumption. The analyses also tested any association between age, sex, rural/urban residence, or a country's economic development and population intake of meat, fruits, and/or vegetables. The review was started in 2017 and completed in 2019.

RESULTS

Richer SSA countries were likely to consume more meat (ß = 36.76, P = 0.04) and vegetables (ß =43.49, P  = 0.00) than poorer countries. Vegetable intake has increased dramatically over the last 3 decades from ≈10 g to ≈110 g (ß = 4.43, P  = 0.00). Vegetable (ß= -25.48, P  = 0.00) consumption was higher in rural than in urban residents. Although the trend of meat consumption has risen (≈25 g to ≈75 g), the trend is nonsignificant (ß = 0.63, N.S.). Daily average per capita meat consumption was 98 g - above the 70 g recommendation - while fruit and vegetable intake (268 g) remain below the World Health Organization's recommendation (400 g).

CONCLUSIONS

Given the low intake of plant-based foods, it is likely that SSA populations may be deficient in high-quality protein and micronutrients as suggested by the EAT-Lancet Commission. There is a need to promote both an adequate supply and demand of plant-based protein and micronutrients, including fruit, vegetables, nuts, seeds, and legumes, in SSA countries. While dietary changes in SSA may offer large absolute benefits, consideration of the magnitude of dietary change, particularly increasing or reducing meat consumption, will need to occur in a way that ensures that policy and interventions support the reduction of undernutrition and micronutrient deficiencies without worsening the prevalence and environmental impacts of noncommunicable diseases. There is also the need for preventive action that ensures that SSA populations do not increase their meat consumption as disposable incomes increase and countries' economic development rises, as is seen in most countries undergoing economic transformation.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42018090497.

A specific class of infectious agents isolated from bovine serum and dairy products and peritumoral colon cancer tissue

The in silico analyses of 109 replication-competent genomic DNA sequences isolated from cow milk and its products (97 in the bovine meat and milk factors 2 group – BMMF2, and additional 4 in BMMF1) seems to place these in a specific class of infectious agents spanning between bacterial plasmid and circular ssDNA viruses. Satellite-type small plasmids with partial homology to larger genomes, were also isolated in both groups. A member of the BMMF1 group H1MBS.1 was recovered in a distinctly modified form from colon tissue by laser microdissection. Although the evolutionary origin is unknown, it draws the attention to the existence of a hitherto unrecognized, broad spectrum of potential pathogens. Indirect hints to the origin and structure of our isolates, as well as to their replicative behaviour, result from parallels drawn to the Hepatitis deltavirus genome structure and replication.

Effects of n-3 and n-6 feeding sources on the quality and lipid oxidation of meat from feedlot-finished Bos indicus steers

This study was conducted to evaluate the fatty acid profile, sensory properties and lipid oxidation of meat on retail display (RD) from Nellore steers (n = 96) fed diets containing soybean (SOY), sunflower (SUN), or linseed (LIN) oil or a control diet (CON). After slaughtering, samples of the Longissimus muscle were collected for sensory properties (1 day), fatty acid composition (1 day) and oxidation stability (3 days under RDC) evaluations. No differences in total lipids, cholesterol, TBARS, and total SFAs, MUFAs, PUFAs, and PUFA/SFA were observed. However, meat from animals fed vegetable oil had more CLA than that of the CON samples. The flavour, juiciness and overall acceptability were affected by the treatments (P < 0.05), but no consistent effect of a specific oil source was observed. Meat colour was not affected by diets or days under RD, and 7-ketocholesterol was not detected in any sample. The oil sources used in this work were not effective in consistently changing meat properties.

Structural analysis of a replication protein encoded by a plasmid isolated from a multiple sclerosis patient

Bovine meat and milk factors (BMMFs) are circular, single-stranded episomal DNAs that have been detected in bovine meat and milk products. BMMFs are thought to have roles in human malignant and degenerative diseases. BMMFs encode a replication initiator protein (Rep) that is actively transcribed and translated in human cells. In this study, a Rep WH1 domain encoded on a BMMF (MSBI1.176) isolated from a multiple sclerosis human brain sample was determined to 1.53 Å resolution using X-ray crystallography. The overall structure of the MSBI1.176 WH1 domain was remarkably similar to other Rep structures, despite having a low (28%) amino-acid sequence identity. The MSBI1.176 WH1 domain contained elements common to other Reps, including five α-helices, five β-strands and a hydrophobic pocket. These new findings suggest that the MSBI1.176 Rep might have comparable roles and functions to other known Reps of different origins.

From "Serum Sickness" to "Xenosialitis": Past, Present, and Future Significance of the Non-human Sialic Acid Neu5Gc

The description of "serum sickness" more than a century ago in humans transfused with animal sera eventually led to identification of a class of human antibodies directed against glycans terminating in the common mammalian sialic acid N-Glycolylneuraminic acid (Neu5Gc), hereafter called "Neu5Gc-glycans." The detection of such glycans in malignant and fetal human tissues initially raised the possibility that it was an oncofetal antigen. However, "serum sickness" antibodies were also noted in various human disease states. These findings spurred further research on Neu5Gc, and the discovery that it is not synthesized in the human body due to a human-lineage specific genetic mutation in the enzyme CMAH. However, with more sensitive techniques Neu5Gc-glycans were detected in smaller quantities on certain human cell types, particularly epithelia and endothelia. The likely explanation is metabolic incorporation of Neu5Gc from dietary sources, especially red meat of mammalian origin. This incorporated Neu5Gc on glycans appears to be the first example of a "xeno-autoantigen," against which varying levels of "xeno-autoantibodies" are present in all humans. The resulting chronic inflammation or "xenosialitis" may have important implications in human health and disease, especially in conditions known to be aggravated by consumption of red meat. In this review, we will cover the early history of the discovery of "serum sickness" antibodies, the subsequent recognition that they were partly directed against Neu5Gc-glycans, the discovery of the genetic defect eliminating Neu5Gc production in humans, and the later recognition that this was not an oncofetal antigen but the first example of a "xeno-autoantigen." Further, we will present comments about implications for disease risks associated with red meat consumption such as cancer and atherosclerosis. We will also mention the potential utility of these anti-Neu5Gc-glycan antibodies in cancer immunotherapy and provide some suggestions and perspectives for the future. Other reviews in this special issue cover many other aspects of this unusual pathological process, for which there appears to be no other described precedent.

Exosomes of pasteurized milk: potential pathogens of Western diseases

Milk consumption is a hallmark of western diet. According to common believes, milk consumption has beneficial effects for human health. Pasteurization of cow's milk protects thermolabile vitamins and other organic compounds including bioactive and bioavailable exosomes and extracellular vesicles in the range of 40-120 nm, which are pivotal mediators of cell communication via systemic transfer of specific micro-ribonucleic acids, mRNAs and regulatory proteins such as transforming growth factor-β. There is compelling evidence that human and bovine milk exosomes play a crucial role for adequate metabolic and immunological programming of the newborn infant at the beginning of extrauterine life. Milk exosomes assist in executing an anabolic, growth-promoting and immunological program confined to the postnatal period in all mammals. However, epidemiological and translational evidence presented in this review indicates that continuous exposure of humans to exosomes of pasteurized milk may confer a substantial risk for the development of chronic diseases of civilization including obesity, type 2 diabetes mellitus, osteoporosis, common cancers (prostate, breast, liver, B-cells) as well as Parkinson's disease. Exosomes of pasteurized milk may represent new pathogens that should not reach the human food chain.

Polyclonal human antibodies against glycans bearing red meat-derived non-human sialic acid N-glycolylneuraminic acid are stable, reproducible, complex and vary between individuals: Total antibody levels are associated with colorectal cancer risk

BACKGROUND

N-glycolylneuraminic acid (Neu5Gc) is a non-human red-meat-derived sialic acid immunogenic to humans. Neu5Gc can be metabolically incorporated into glycan chains on human endothelial and epithelial surfaces. This represents the first example of a "xeno-autoantigen", against which circulating human "xeno-autoantibodies" can react. The resulting inflammation ("xenosialitis") has been demonstrated in human-like Neu5Gc-deficient mice and contributed to carcinoma progression via antibody-mediated inflammation. Anti-Neu5Gc antibodies have potential as biomarkers for diseases associated with red meat consumption such as carcinomas, atherosclerosis, and type 2 diabetes.

METHODS

ELISA assays measured antibodies against Neu5Gc or Neu5Gc-glycans in plasma or serum samples from the Nurses' Health Studies, the Health Professionals Follow-up Study, and the European Prospective Investigation into Cancer and Nutrition, including inter-assay reproducibility, stability with delayed sample processing, and within-person reproducibility over 1-3 years in archived samples. We also assessed associations between antibody levels and coronary artery disease risk (CAD) or red meat intake. A glycan microarray was used to detected antibodies against multiple Neu5Gc-glycan epitopes. A nested case-control study design assessed the association between total anti-Neu5Gc antibodies detected in the glycan array assay and the risk of colorectal cancer (CRC).

RESULTS

ELISA assays showed a wide range of anti-Neu5Gc responses and good inter-assay reproducibility, stability with delayed sample processing, and within-person reproducibility over time, but these antibody levels did not correlate with CAD risk or red meat intake. Antibodies against Neu5Gc alone or against individual Neu5Gc-bearing epitopes were also not associated with colorectal cancer (CRC) risk. However, a sialoglycan microarray study demonstrated positive association with CRC risk when the total antibody responses against all Neu5Gc-glycans were combined. Individuals in the top quartile of total anti-Neu5Gc IgG antibody concentrations had nearly three times the risk compared to those in the bottom quartile (Multivariate Odds Ratio comparing top to bottom quartile: 2.98, 95% CI: 0.80, 11.1; P for trend = 0.02).

CONCLUSIONS

Further work harnessing the utility of these anti-Neu5Gc antibodies as biomarkers in red meat-associated diseases must consider diversity in individual antibody profiles against different Neu5Gc-bearing glycans. Traditional ELISA assays for antibodies directed against Neu5Gc alone, or against specific Neu5Gc-glycans may not be adequate to define risk associations. Our finding of a positive association of total anti-Neu5Gc antibodies with CRC risk also warrants confirmation in larger prospective studies.

Paediatric Virology and its interaction between basic science and clinical practice (Review)

The 3rd Workshop on Paediatric Virology, which took place on October 7th, 2017 in Athens, Greece, highlighted the role of breast feeding in the prevention of viral infections during the first years of life. Moreover, it focused on the long-term outcomes of respiratory syncytial virus and rhinovirus infections in prematurely born infants and emphasised the necessity for the development of relevant preventative strategies. Other topics that were covered included the vaccination policy in relation to the migration crisis, mother‑to‑child transmission of hepatitis B and C viruses, vaccination against human papilloma viruses in boys and advances on intranasal live‑attenuated vaccination against influenza. Emphasis was also given to the role of probiotics in the management of viral infections in childhood, the potential association between viral infections and the pathogenesis of asthma, fetal and neonatal brain imaging and the paediatric intensive care of children with central nervous system viral infections. Moreover, an interesting overview of the viral causes of perinatal mortality in ancient Greece was given, where recent archaeological findings from the Athenian Agora's bone well were presented. Finally, different continuing medical educational options in Paediatric Virology were analysed and evaluated. The present review provides an update of the key topics discussed during the workshop.

Expression and replication of virus-like circular DNA in human cells

The consumption of bovine milk and meat is considered a risk factor for colon- and breast cancer formation, and milk consumption has also been implicated in an increased risk for developing Multiple Sclerosis (MS). A number of highly related virus-like DNAs have been recently isolated from bovine milk and sera and from a brain sample of a MS patient. As a genetic activity of these Acinetobacter-related bovine milk and meat factors (BMMFs) is unknown in eukaryotes, we analyzed their expression and replication potential in human HEK293TT cells. While all analyzed BMMFs show transcriptional activity, the MS brain isolate MSBI1.176, sharing homology with a transmissible spongiform encephalopathy-associated DNA molecule, is transcribed at highest levels. We show expression of a replication-associated protein (Rep), which is highly conserved among all BMMFs, and serological tests indicate a human anti-Rep immune response. While the cow milk isolate CMI1.252 is replication-competent in HEK293TT cells, replication of MSBI1.176 is complemented by CMI1.252, pointing at an interplay during the establishment of persistence in human cells. Transcriptome profiling upon BMMF expression identified host cellular gene expression changes related to cell cycle progression and cell viability control, indicating potential pathways for a pathogenic involvement of BMMFs.

A prokaryotic viral sequence is expressed and conserved in mammalian brain

A natural and permanent transfer of prokaryotic viral sequences to mammals has not been reported by others. Circular "SPHINX" DNAs <5 kb were previously isolated from nuclease-protected cytoplasmic particles in rodent neuronal cell lines and brain. Two of these DNAs were sequenced after Φ29 polymerase amplification, and they revealed significant but imperfect homology to segments of commensal Acinetobacter phage viruses. These findings were surprising because the brain is isolated from environmental microorganisms. The 1.76-kb DNA sequence (SPHINX 1.8), with an iteron before its ORF, was evaluated here for its expression in neural cells and brain. A rabbit affinity purified antibody generated against a peptide without homology to mammalian sequences labeled a nonglycosylated ∼41-kDa protein (spx1) on Western blots, and the signal was efficiently blocked by the competing peptide. Spx1 was resistant to limited proteinase K digestion, but was unrelated to the expression of host prion protein or its pathologic amyloid form. Remarkably, spx1 concentrated in selected brain synapses, such as those on anterior motor horn neurons that integrate many complex neural inputs. SPHINX 1.8 appears to be involved in tissue-specific differentiation, including essential functions that preserve its propagation during mammalian evolution, possibly via maternal inheritance. The data here indicate that mammals can share and exchange a larger world of prokaryotic viruses than previously envisioned.