A study has identified 70 virus lineages with the highest potential for causing a global pandemic, emphasizing the importance of monitoring viruses related to known human pathogens. This research supports the preparation for future pandemics by informing vaccine and diagnostic development and refining surveillance efforts to focus on the most threatening RNA viruses.
Understanding the ancestry of virusA virus is a tiny infectious agent that is not considered a living organism. It consists of genetic material, either DNA or RNA, that is surrounded by a protein coat called a capsid. Some viruses also have an outer envelope made up of lipids that surrounds the capsid. Viruses can infect a wide range of organisms, including humans, animals, plants, and even bacteria. They rely on host cells to replicate and multiply, hijacking the cell's machinery to make copies of themselves. This process can cause damage to the host cell and lead to various diseases, ranging from mild to severe. Common viral infections include the flu, colds, HIV, and COVID-19. Vaccines and antiviral medications can help prevent and treat viral infections.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>virus families may assist researchers in pinpointing which variants possess the potential to become Disease X, the elusive pathogen responsible for the next worldwide pandemic.
A study has identified 70 virus lineages – groups of related viruses – that pose the biggest risk. Viruses from other genetic backgrounds are unlikely to cause a high number of infections in humans, the research shows.
The findings will support ongoing efforts to monitor and prepare for future pandemics, including guiding vaccine and diagnostic development, experts say.
Understanding Disease X and RNA Viruses
Disease X is the generic term used by the World Health Organization to represent a hypothetical, unidentified pathogen that could pose a significant threat to people.
RNARibonucleic acid (RNA) is a polymeric molecule similar to DNA that is essential in various biological roles in coding, decoding, regulation and expression of genes. Both are nucleic acids, but unlike DNA, RNA is single-stranded. An RNA strand has a backbone made of alternating sugar (ribose) and phosphate groups. Attached to each sugar is one of four bases—adenine (A), uracil (U), cytosine (C), or guanine (G). Different types of RNA exist in the cell: messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA).” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>RNA viruses carry their genetic information as RNA, a structure similar to DNADNA, or deoxyribonucleic acid, is a molecule composed of two long strands of nucleotides that coil around each other to form a double helix. It is the hereditary material in humans and almost all other organisms that carries genetic instructions for development, functioning, growth, and reproduction. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>DNA. They cause many diseases, including the common cold, Covid-19 and measles, and have been responsible for most epidemics, or global pandemics, in recent history.
Monitoring RNA viruses in animal populations could help to identify those that are most likely to emerge and spread rapidly in humans. However, the huge number in circulation makes this extremely challenging and expensive.
Research Findings and Epidemic Potential
The University of Edinburgh-led research team traced the lineage, or family tree, of 743 distinct RNA virus speciesA species is a group of living organisms that share a set of common characteristics and are able to breed and produce fertile offspring. The concept of a species is important in biology as it is used to classify and organize the diversity of life. There are different ways to define a species, but the most widely accepted one is the biological species concept, which defines a species as a group of organisms that can interbreed and produce viable offspring in nature. This definition is widely used in evolutionary biology and ecology to identify and classify living organisms.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>species to track how they evolved, including all species currently known to infect humans.
Researchers compared the development of strictly zoonotic viruses – those that spread from animals to humans, but not between people – with human-transmissible viruses, which can spread within human populations.
The findings showed that viruses that can spread within human populations typically evolve separately from strictly zoonotic viruses.
Human-transmissible viruses often emerge when related viruses from the same lineage can already spread between humans.
Strictly zoonotic viruses have historically not led to epidemics in human populations. Having a close relative that can infect humans, but not spread between them, does not appear to increase the risk of epidemic potential.
Implications for Pandemic Preparedness
The research team cautioned that there is still a chance the next pandemic could come as the result of a strictly zoonotic virus – such as bird flu – or an entirely new virus. However, the findings offer a route to help streamline surveillance for Disease X among the vast number of RNA viruses in existence.
Professor Mark Woolhouse, Professor of Infectious Disease Epidemiology at the University of Edinburgh, said: “Viruses without the right ancestry don’t seem to cause epidemics. Out of potentially huge numbers of mammal and bird viruses in circulation, we should concentrate on the ones that are related to existing human viruses with epidemic potential. This research narrows the search for the next Disease X enormously.”
Reference: “Temporal Dynamics, Discovery, and Emergence of Human-Transmissible RNA Viruses” by Lu Lu, Feifei Zhang, Liam Brierley, Gail Robertson, Margo Chase-Topping, Samantha Lycett and Mark Woolhouse, 18 January 2024, Molecular Biology and Evolution.
DOI: 10.1093/molbev/msad272
The research team included scientists from the Universities of Edinburgh and Liverpool and Peking University in China. The study was funded by the EU Horizon 2020 programme and the BBSRC.
Source: SciTechDaily
