Коронавирусите не се нови; тие се стари колку што било во светот и познато е дека предизвикуваат обична настинка кај луѓето со векови. Сепак, неговата најнова варијанта, „SARS-CoV-2“ моментално е во вести за предизвикување СОВИД-19 пандемијата е нова.
Often, common cold (caused by коронавирус и други вируси како што се риновируси) се меша со грип.
Flu and common cold, though both present similar symptoms are different in the sense that they are caused by different вируси заедно.
Flu or influenza вируси have a segmented genome which cause antigenic shift which occurs due to recombination among вируси 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 structure) over a period of time that causes changes in the nature of surface proteins. All this makes it difficult to develop vaccine against them that could provide protection for long duration. The last pandemic of Spanish Flu of 1918 that killed millions of people was caused by flu or influenza вирус. This is different from the coronaviruses.
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 коронавируси is normally limited to cold symptoms only and rarely made anyone seriously sick. However, there were some virulent forms of коронавируси 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.
најновите варијанта of коронавирус, the novel 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, што може да предизвика вакво драстично антигенско движење што го направи САРС-КоВ-2 толку вирулентен и заразен?
Во научната заедница кружат неколку теории кои укажуваат на потеклото на САРС-КоВ-23,4. 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 затоа што ако луѓето би го создале 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 еволуција?
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Референци:
- Padron-Regalado E. Вакцини за САРС-КоВ-2: Лекции од други видови на коронавирус [објавено онлајн пред печатење, 2020 април 23 година]. Инфицирај дис. 2020;9(2):1-20. doi: https://doi.org/10.1007/s40121-020-00300-x
- Liangsheng Z, Fu-ming S, Fei C, Zhenguo L. Потекло и еволуција на романот коронавирус од 2019 година, Клинички инфективни болести, том 71, број 15, 1 август 2020 година, страници 882–883, DOI:https://doi.org/.1093/cid/ciaa112
- Моренс Д.М., Бреман Џ.Г. и сор. 2020 година. Американското здружение за тропска медицина и хигиена. Достапно на интернет: 19 јули 22 година. DOI: https://doi.org/10.4269/ajtmh.20-0849
- Јорк А. Новиот коронавирус лета од лилјаци? Nat Rev Microbiol 18, 191 (2020). DOI:https://doi.org/10.1038/s41579-020-0336-9
- Андерсен КГ, Рамбо, А., Липкин, В.И и сор. Проксималното потекло на САРС-КоВ-2. Нат Мед 26, 450-452 (2020). DOI: https://doi.org/10.1038/s41591-020-0820-9.
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