The process of viremia involving the transfer of the whole virus from pulmonary alveolar epithelial pneumocytes to the alveolar capillaries and hence to the systemic circulation is not well described in the literature to date. I would like to open a discussion in regard to how some of our readers feel this process - mechanism is occurring.
Please provide your thoughts, ideas, and hypothesis for this process and also provide references when they are found. This process is sometimes explained for the "SARS-CoV-2 RNAemia" but not for the intact whole infective SARS-CoV-2 virus.
Jesus F Bermejo-Martin, Milagros Gonzalez-Rivera, Raquel Almansa, et al. SARS-CoV-2 RNA viremia is associated with a sepsis-like host response and critical illness in COVID-19. medRxiv. doi: https://doi.org/10.1101/2020.08.25.20154252
"SARS-CoV-2 RNA is commonly detected in nasopharyngeal swabs, however viral RNA can be found also in peripheral blood and other tissues. Whether systemic spreading of the virus or viral components plays a role in the pathogenesis of the sepsis like disease observed in severe COVID-19 is currently unknown."
I look forward to your thoughts and answers to this question and some of the exchanges of information in this question thread.
Melvin R (Pete) Hayden
University of Missouri School of Medicine
SARS-CoV-2 viremia and mechanism of extra-pulmonary manifestations of COVID-19
After initial infection of the pulmonary tissue, and SARS-CoV-2 replication, the viremia leads to seeding of all body tissues through the blood. This has been more well characterized with SARS-CoV-1 (1). Because ACE2, the entry receptor for the causative corona-virus SARS-CoV-2, is expressed in multiple extrapulmonary tissues, direct viral tissue damage is a plausible mechanism of injury. Besides this, endothelial damage, thromboinflammation, dysregulation of immune responses, and maladaptation of ACE2-related pathways might all contribute to the extrapulmonary manifestations of COVID-19 (2).
1. Article Antibody response and viraemia during the course of severe a...
2. Article Extrapulmonary manifestations of COVID-19
Dr. Yousuf,
Thank you for your answer and helpful thoughts and especially the link to the references.
I found article 2 - Extrapulmonary manifestation of COVID-19 extremely informative and helpful!
I will continue to read and increase my understanding of the intact virus viremia associated with COVID-19. From your insights and reading it appears that the microvascular endothelial cell may be involved in the progression of viremia to involve the extrapulmonary tissues. I am also interested in the effects of the virus
on the red blood cells upon entry into the microcirculation and also the macrocirculation once it has breached the Air-blood barrier.
pete hayden
Covid 19 virus has affinity to enzyme Angio converting enzyme - 2 (ACE-2) locate on the alveolar cell of the lung to form its receptor. The lung has 3 types of alveolar cells: type 1 responsible for gaseous exchange, type 2 are surfactant in nature and contain protein and fats that reduces surface tension on the lung and type 3 are dust cells which are phagocytic, COVID-19, contain a protein envelope called spikes that help it to bind on the receptor (ACE-2) to determine its virulence in the host after infection, After a heavy infestation of the pathogenic Covid 19 virus on the lung it gain access to lung arteries and lung veins,which are attacked severerly, then result to burst of infected lung vessels into blood circulation to mix with blood thus viremia, noted by a sudden drop of blood pressure (BP), patient put on mechical ventilators in ICU to support respiratory pocess.
The cell wall of virus is rounded by the spike that make it to resemble the crown.
Dr Silali ,
Thank you for you informative answer I concur but have had difficulty finding any references to this mechanisms. When writing, one feels an obligation to provide references regarding the mechanisms in regards to the development of Viremia.
Your thoughts and concepts are greatly appreciated and I wish to thank you.
pete hayden
Gratitude Dr. Melvin Hayden, reference of the material are foud in the article published in April 2020 : Citation: Maurice B Silali. “Factors Associated with Low Virulence in the Infective COVID-19 Virus in Africa with the Pandemic infection Rise". Acta Scientific Medical Sciences 4.4 (2020): 130-134. on subtopic mode of transmission and pathogenesis of COVID 19 virus. and also in research gate of Covid 19 community column. warm regards.
Today I thought that I would upload the recent preprint discussing the lymphatic system in relation to Viremia in section 3 of this preprint. This paper has been submitted for publication; however, it may be awhile before author learns of its destiny... the opportunity to present this paper was offered in preprints so I took this opportunity.
3. Viremia: The Lymphatic System
This preprint paper is open for discussion to all
Sincerely and wishes for a HAPPY NEW YEAR TO ALL
Melvin R. Hayden, MD
University of Missouri School of Medicine
Columbia, Missouri USA