Коронавирусы не новы; они стары, как все на свете, и, как известно, веками вызывают простуду у людей. Тем не менее, его последний вариант, SARS-CoV-2, в настоящее время в новостях из-за того, что Covid-19. пандемия новая.
Often, common cold (caused by коронавирус и другие вирусы такие как риновирусы) путают с гриппом.
Грипп и простуда, хотя и имеют схожие симптомы, разные в том смысле, что они вызваны разными вирусами.
Flu or influenza viruses have a segmented genome which cause antigenic shift which occurs due to recombination among viruses of the same genus, thus changing the nature of the proteins on the viral surface responsible for generating immune response. This is further complicated by a phenomenon called antigenic drift which results from вирус accumulating mutations (change in its ДНК структура) в течение периода времени, который вызывает изменения в природе поверхностных белков. Все это затрудняет разработку вакцины против них, которая могла бы обеспечить защиту на длительный срок. Последняя пандемия испанского гриппа 1918 года, унесшая жизни миллионов людей, была вызвана вирусом гриппа или гриппа. Это отличается от коронавирусов.
Coronaviruses, responsible for causing Common cold, on the other hand, do not possess a segmented genome hence there is no antigenic shift. They were minimally virulent and occasionally lead to death of the affected people. The virulence of коронавирус is normally limited to cold symptoms only and rarely made anyone seriously sick. However, there were some virulent forms of коронавирус in the recent past, namely SARS (Severe Acute Respiratory Syndrome) that appeared in 2002-03 in Southern China and caused 8096 cases, resulting in 774 deaths in 26 countries and MERS (Middle East Respiratory Syndrome) that appeared 9 years later in 2012 in Saudi Arabia and caused 2494 cases, resulting in 858 deaths in 27 countries1. However, this remained endemic and disappeared relatively quickly (within 4-6 months), possibly due to its less virulent nature and/or by following proper epidemiological procedures for containment. Hence, no need was felt at that time to invest heavily and develop a vaccine against such a коронавирус.
В последнем вариант of коронавирус, Роман коронавирус (SARS-CoV-2) seems to be related to SARS and MERS2 which is highly infectious and virulent in humans. It was identified first in Wuhan China but soon became an epidemic and spread across the world to take the form of pandemic. Was this rapid spread across select geographies solely due to the high virulence and infectivity caused by changes in the genetic constitution of the вирус or possibly due to lack of timely epidemiological intervention by reporting to the concerned national/transnational authorities which prevented timely containment measures, thereby causing about a million deaths so far and bringing the world economy to the grinding halt.
This is the first time in the human history that the existing коронавирус reportedly underwent changes in its genome that made it into a highly virulent variant, responsible for the current pandemic.
Но что могло вызвать такой резкий антигенный дрейф, сделавший SARS-CoV-2 таким опасным и заразным?
В научном сообществе ходит несколько теорий, указывающих на происхождение SARS-CoV-2.3,4. Proponents of man-made origin of the вирус believe that the genome changes seen in SARS-CoV-2 would take am extremely long period of time to develop naturally, while other studies argue that it may be of natural origin5 потому что если бы люди создали вирус artificially, why would they create a sub-optimal form that is virulent enough to cause a severe disease but binds sub-optimally to the human cells and the fact that it was not created using the backbone of the known вирус.
Be as it may, the fact of the matter remains that a certain almost innocuous вирус underwent genetic changes to transform itself to become mildly virulent SARS/MERS, and finally into a highly infectious and virulent form (SARS-CoV-2) in a span of 18-20 years, appears unusual. Such drastic antigenic drift, which incidentally has a continuum in between, would be highly unlikely to happen in a normal course, in the laboratory of Mother Earth, in such a short time duration. Even if it were to be true, what’s more perplexing is the environmental pressure that would have triggered such a selection in the эволюция?
Ссылки:
- Падрон-Регаладо Э. Вакцины от SARS-CoV-2: уроки других штаммов коронавируса [опубликовано в Интернете перед печатью, 2020 апреля 23 г.]. Заражение Dis Ther. 2020;9(2):1-20. doi: https://doi.org/10.1007/s40121-020-00300-x
- Liangsheng Z, Fu-ming S, Fei C, Zhenguo L. Происхождение и эволюция нового коронавируса 2019 г., Clinical Infectious Diseases, Volume 71, Issue 15, 1 августа 2020 г., страницы 882–883, DOI:https://doi.org/.1093/cid/ciaa112
- Моренс Д.М., Бреман Дж. Г. и др., 2020. Происхождение COVID-19 и его значение. Американское общество тропической медицины и гигиены. Доступно онлайн: 22 июля 2020 г. DOI: https://doi.org/10.4269/ajtmh.20-0849
- Йорк А. Новый коронавирус улетает от летучих мышей? Nat Rev Microbiol 18, 191 (2020). DOI:https://doi.org/10.1038/s41579-020-0336-9
- Андерсен К.Г., Рамбаут А., Липкин В.И. и другие Проксимальное происхождение SARS-CoV-2. Nat Med 26. С. 450–452 (2020). DOI: https://doi.org/10.1038/s41591-020-0820-9.
