LETTER

Viruses from poultry and livestock pose continuous threats to human beings LETTER Si Chena,1, Liying Zhanga,1, Lin Wangb, Hongsheng Ouyanga, and Linzhu Rena,2

Recently, the paper by Edwards et al. (1) reports that syndrome-related CoV and the Middle East respira- swine acute diarrhea syndrome (SADS-CoV, tory syndrome-related CoV may have diverged from also known as porcine enteric ) can rep- bat in the past three decades and trans- licateinprimaryhumancells,especially human lung and ferred from bat to human via palm civet and drome- intestinal cells. These results indicate that more attention dary camel, respectively (2). We previously also found should be paid to from poultry and livestock, that human cells were permissive for the productive which have a wide host spectrum. infection of porcine circovirus (3). Moreover, to date, As estimated, more than 60% of existing human there are six known porcine coronaviruses, including infectious diseases are zoonotic, and at least 75% of porcine epidemic diarrhea (PEDV), transmissible emerging infectious diseases of humans (including gastroenteritis virus (TGEV), porcine Ebola, HIV, and influenza) have an animal origin, with (PDCoV), SADS-CoV, porcine respiratory coronavirus more than five new human diseases appearing each (PRCV), and porcine hemagglutinating encephalomy- year. Poultry and domestic animals (including pets) are elitis virus (PHEV). PEDV, TGEV, SADS-CoV, and PRCV animals that have the most contact with human belong to Alphacoronavirus, while PHEV and PDCoV beings. Their living environment, especially in large- belong to and Deltacoronavirus, re- scale farming, is very similar to that of human beings, spectively. Therefore, pigs, as well as other domestic which provides suitable conditions for the evolution animals, may serve as mixers for virus recombination, and variation of viruses, and thus these animals be- and, subsequently, a new virus may appear in domes- come suitable intermediate hosts or mixers for viruses tic animals or transmit to humans, which indicates that to infect human beings. viruses from poultry, livestock, and pets pose contin- During past decades, some groups have proved uous threats to human beings. For this reason, more that several viruses that cause human infection or attention and more funding should be given to veter- epidemic come from poultry and livestock, among inary medicine and veterinary research, which will play which coronaviruses, rabies virus, and influenza viruses a critical role in controlling diseases before they are the most frequently reported viruses, which have spread to humans. caused great harm to human health and public health safety. As reported, the appearance of human coro- Acknowledgments navirus 229E (HCoV 229E) was roughly estimated to This work was financially supported by the National Key Research be about 200 y ago, and was transferred from bat to and Development Program of China (Grant 2017YFD0500103), alpacas and then to humans (2). About 120 y ago, the National Natural Science Foundation of China (Grant 31772747), and the Jilin Province Science and Technology HCoV OC43, which was considered to have a com- Development Projects (Grant 20200402043NC). The funders mon ancestor with bovine coronavirus, was transmit- had no role in the study design, data collection and analysis, ted from cattle to humans (2). Severe acute respiratory decision to publish, or preparation of the manuscript.

1 C. E. Edwards et al., Swine acute diarrhea syndrome coronavirus replication in primary human cells reveals potential susceptibility to infection. Proc. Natl. Acad. Sci. U.S.A. 117, 26915–26925 (2020). 2 D. Forni, R. Cagliani, M. Clerici, M. Sironi, Molecular evolution of human coronavirus genomes. Trends Microbiol. 25,35–48 (2017). 3 X. Liu et al., Human cells are permissive for the productive infection of porcine circovirus type 2 in vitro. Sci. Rep. 9, 5638 (2019).

aJilin Provincial Key Laboratory of Animal Embryo Engineering, College of Animal Sciences, Jilin University, Changchun 130062, China; and bKey Lab for Zoonoses Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun 130062, China Author contributions: L.R. designed research; and S.C., L.Z., L.W., and H.O. wrote the paper. The authors declare no competing interest. Published under the PNAS license. 1S.C. and L.Z. contributed equally to this work. 2To whom correspondence may be addressed. Email: [email protected]. Published January 7, 2021.

PNAS 2021 Vol. 118 No. 3 e2022344118 https://doi.org/10.1073/pnas.2022344118 | 1of1 Downloaded by guest on October 2, 2021