Quantitative Analysis of SARS-CoV-2 Viral Load in the Lungs of COVID-19 Deceased Patients

Abstract

The objective : to perform quantitative analysis of SAR S -C o V-2 viral load ( VL ) levels in lung tissues in deceased patients with COVI D -1 9 and to evaluate its association with the nature of histological changes in the lungs and the duration of stay in ICU till the lethal outcome. Subjects and Methods. Sections of formali n-f ixed and paraffi n-e mbedded lung tissues of 36 deceased patients with COVI D -1 9 were used. The SAR S -C o V-2 viral load was quantitatively assessed using the original q PCR . VL was calculated using the following formula: copies SAR S -C o V-2 / copies ABL 1 × 100, expressed as the ratio of the true number of SAR S -C o V-2 c DNA copies per 100 copies of ABL 1 gene c DNA . Results . In cases with no histological changes typical of diffuse alveolar lung injury ( DAI ), the detection rate of SAR S -C o V-2 RNA and the average level of the SAR S -C o V-2 viral load were 62.5% (5 out of 8 observations) and 104.75 (range 0-3 13) copies of SAR S -C o V-2 c DNA per 100 copies of human ABL 1 gene c DNA . The average level of the SAR S -C o V-2 viral load in the lungs with prevailing histological changes characteristic of the proliferative and exudative phases of DAI differed by 60 times and amounted to 909 (1 8-2 ,657) and 54,924 (83 4-2 50,281) copies of SAR S -C o V-2 c DNA per 100 copies of human ABL 1 c DNA , respectively. The average duration of stay in the intensive care unit in the group of patients with exudative and proliferative phases of DAI was 10.64 ( 1-2 2) and 8.14 ( 1-2 1) be d-d ays, respectively. The detection rate of the SAR S -C o V-2 RNA in patients with diffuse alveolar lung injury was 100%.