Virus World

Wildlife is reservoir of emerging viruses. Here we identified 27 families of mammalian viruses from 1981 wild animals and 194 zoo animals collected from south China between 2015 and 2022, isolated and characterized the pathogenicity of eight viruses. Bats harbor high diversity of coronaviruses, picornaviruses and astroviruses, and a potentially novel genus of Bornaviridae. In addition to the reported SARSr-CoV-2 and HKU4-CoV-like viruses, picornavirus and respiroviruses also likely circulate between bats and pangolins. Pikas harbor a new clade of Embecovirus and a new genus of arenaviruses. Further, the potential cross-species transmission of RNA viruses (paramyxovirus and astrovirus) and DNA viruses (pseudorabies virus, porcine circovirus 2, porcine circovirus 3 and parvovirus) between wildlife and domestic animals was identified, complicating wildlife protection and the prevention and control of these diseases in domestic animals. This study provides a nuanced view of the frequency of host-jumping events, as well as assessments of zoonotic risk. Monitoring the diversity of viruses infecting animals is important for assessing zoonotic risk. Here, the authors use metatranscriptomics to characterise the viromes of small mammals, pangolins, and zoo animals in China to identify potentially zoonotic viruses.

Published in Nature Comm. (April 29, 2023):

https://doi.org/10.1038/s41467-023-38202-4 

It’s no coincidence that some of the worst viral disease outbreaks in recent years — SARS, MERS, Ebola, Marburg and likely the newly arrived 2019-nCoV virus — originated in bats. A new University of California, Berkeley, study finds that bats’ fierce immune response to viruses could drive viruses to replicate faster, so that when they jump to mammals with average immune systems, such as humans, the viruses wreak deadly havoc. Some bats — including those known to be the original source of human infections — have been shown to host immune systems that are perpetually primed to mount defenses against viruses. Viral infection in these bats leads to a swift response that walls the virus out of cells. While this may protect the bats from getting infected with high viral loads, it encourages these viruses to reproduce more quickly within a host before a defense can be mounted. This makes bats a unique reservoir of rapidly reproducing and highly transmissible viruses. While the bats can tolerate viruses like these, when these bat viruses then move into animals that lack a fast-response immune system, the viruses quickly overwhelm their new hosts, leading to high fatality rates.

“Some bats are able to mount this robust antiviral response, but also balance it with an anti-inflammation response,” said Cara Brook, a postdoctoral Miller Fellow at UC Berkeley and the first author of the study. “Our immune system would generate widespread inflammation if attempting this same antiviral strategy. But bats appear uniquely suited to avoiding the threat of immunopathology.” The researchers note that disrupting bat habitat appears to stress the animals and makes them shed even more virus in their saliva, urine and feces that can infect other animals. “Heightened environmental threats to bats may add to the threat of zoonosis,” said Brook, who works with a bat monitoring program funded by DARPA (the U.S. Defense Advanced Research Projects Agency) that is currently underway in Madagascar, Bangladesh, Ghana and Australia. The project, Bat One Health, explores the link between loss of bat habitat and the spillover of bat viruses into other animals and humans.

“The bottom line is that bats are potentially special when it comes to hosting viruses,” said Mike Boots, a disease ecologist and UC Berkeley professor of integrative biology. “It is not random that a lot of these viruses are coming from bats. Bats are not even that closely related to us, so we would not expect them to host many human viruses. But this work demonstrates how bat immune systems could drive the virulence that overcomes this.”....

Published in Ecology Epidemiology and Global Health (03 February, 2020):

https://doi.org/10.7554/eLife.48401

Researchers at the University of Duke found mRNA-based vaccines, such as Pfizer and Moderna, induce antibodies that may help fight against coronavirus variants.  The Pfizer and Moderna vaccines are not only effective against COVID-19, but may also help prevent future pandemics. Researchers at Duke University came to this concluding after testing mRNA-based vaccines similar to the jabs used on lab monkeys. According to their findings, which were published in Nature this week, these variety of vaccines induced “broadly neutralizing” antibodies that appeared to protect against Sars-CoV-2—the infection that causes COVID-19—as well as potential variants of coronavirus that could jump from animal to human.  The findings may offer the public a sense of relief as many experts and epidemiologists say there’s a strong chance another pandemic will occur. In an effort to help prevent another outbreak, the team of Duke University researchers developed a pan-coronavirus vaccine that is protein-based rather than mRNA-based. The vaccine was tested on lab animals and showed promising results in fighting the original COVID-19 strain and other variants. Researchers said the vaccine also appeared to stop the virus from replicating in the lungs and nose, which could drastically reduce rates of transmission.

“We began this work last spring with the understanding that, like all viruses, mutations would occur in the SARS-CoV-2 virus,” the study’s senior author Barton F. Haynes, director of the Duke Human Vaccine Institute, said in a press release. “The mRNA vaccines were already under development, so we were looking for ways to sustain their efficacy once those variants appeared. This approach not only provided protection against SARS-CoV-2, but the antibodies induced by the vaccine also neutralized variants of concern that originated in the United Kingdom, South Africa and Brazil. And the induced antibodies reacted with quite a large panel of coronaviruses.”  Dr. Anthony Fauci, the nation’s leading expert in infectious diseases, expressed optimism about Duke’s pan-coronavirus vaccine during a Thursday press conference, saying the next step was to get approval for human trials. “We always have to have a caveat when you’re dealing in a nonhuman primate,” he said, “nonetheless, this is an extremely important proof of concept that we will be aggressively pursuing as we get into the development of human trials,” Fauci said.

Cited study published in Nature (May 10, 2021):

https://doi.org/10.1038/s41586-021-03594-0