الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The pandemic caused by SARS-CoV-2, resulted in a serious health condition around the
world. Despite the ongoing exposure to SARS-CoV-2 and the ongoing development of new viral
mutations, mass vaccination programs along with natural herd immunity had an obvious impact
on reducing the viral load and hindering the progression of COVID-19 to its severe form. This
took most countries of the world to the post-SARS-CoV-2 vaccination era, with the lifting of
COVID-19 social restrictions.
Several laboratory studies and computationally bioinformatics research had offers insight
on the impact of microRNA molecules in COVID-19 pathogenesis. As a result of their serum
stability, several microRNA molecules have been recommended as potential biomarkers that can
indicate the severity and likely outcome of COVID-19 illness situations.
The two MicroRNA molecules, miR155-5p and miR200c-3p, have been suggested as
useful diagnostic biomarkers for COVID-19, based on experimentally observed correlations
between their serum and/or cellular levels and the degree of severity of COVID-19.
This study aimed to investigate the expression levels of circulating miR155-5p and
miR200c-3p during SARS-CoV-2 infection and comparing their relative expression levels
between infected patients and healthy controls.
This was a cross-sectional case control study conducted during the period from December
2021 to February 2022 in Alexandria, Egypt. The study included 30 COVID-19 confirmed
infected patients attended to the outpatient clinic of AMUH. Twenty healthy patients of matched
ages were included as controls.
Blood samples were collected from patients and control group under the study. Plasma
was separated, aliquoted, and stored immediately at -80 °C until subsequent processing. The data
including socio-demographic data, symptoms, oxygen saturation and status of vaccination were
collected from the patients. Moreover, total and differential complete blood cell count (CBC)
data were collected. The RNA was extracted from the plasma and the expression level of
miR155-5p and miR200c-3p was analyzed using quantitative real-time polymerase chain reaction
(PCR).
The 30 patients were subcategorized into two groups [mild (n=16) and moderate (n=14)]
based on their clinical picture, laboratory, and radiological findings. Nineteen of the patients
(63.3%) were fully vaccinated against SARS-CoV-2, while 11 (36.7%) were unvaccinated.
The female percentage was higher in both mild and moderate cases (81.3% and 64.3%
respectively), while the percentage of male (65%) was more than female in control group. The
mean ages of mild, moderate cases and control group were 35.2 ± 9.6, 36.6 ± 14.8 and 38.9 ±
10.2 years, respectively. However, there were no statistical association between sex or age with
disease severity and the expression of both miR-155 and miR-200c. There was no statistical
difference regarding comorbidity (hypertension, history of respiratory infection and diabetes)
between mild and moderate cases. Hypertension represented the most common comorbidity
among COVID-19 patients. Most reported clinical presentation was body aches/ fatigue (77%),
SUMMARY, CONCLUSIONS AND RECOMMENDATIONS
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cough (70%) and fever (70%), nevertheless no statistically significant association between
symptoms and disease severity was found.
High O2 saturation (97% - 99%) and normal platelet count (mean of 230.2 ± 60.6 x 10^3
cells/μl in mild cases and 259 ± 137.8 x 10^3 cells/μl in moderate cases) were reported.
Moreover, 100% of mild cases and 85.7% of moderate cases revealed normal leukocyte count
with increased relative monocytosis (62.5% of mild cases and 78.6% of moderate cases) (p >
0.05).
Results showed that the expression levels of miR155-5p and miR200c-3p were
significantly downregulated in COVID-19 patients compared to the healthy control group (p ˂
0.005). Furthermore, the results revealed a statistically significant positive correlation between
the expression of miR155-5p and miR200c-3p (p <0.001) in COVID-19 patients. Despite
downregulation of miR-155 expression in mild and moderate cases compared to control group,
there was statistically significant higher level of expression among the moderate cases compare
to mild cases. Both miR155-5p and miR200c-3p were of 70% sensitivity as diagnostic
biomarkers of COVID-19, with a specificity of 80% and 77%, respectively. Regarding their role
in the assessment of COVID-19 severity, both biomarkers showed low sensitivity (64.3%),
however, miR155-5p showed 94% specificity compared to 75% for miR200c-3p.
No statistically significant correlation was reported between the vaccination status of the
patients and the severity of the clinical condition (mild and moderate cases of infection), the
presented symptoms, the CBC analyses, or the expression levels of miR155-5p and miR200c-3