Study of circulating biomarkers in inpatients infected with SARS-CoV-2 alpha mutant

The alpha variant (B.1.1.7) of Severe Acute Respiratory Syndrome coronavirus-2 (SARS-CoV-2) emerged as the predominant strain in the United Kingdom in late 2020 and early 2021. The results are more severe in mutants that are more infectious, have weakened immunity, and are clinically mutated. Spike protein..

Now, a new study published in medRxiv* The preprint server proposes a rapid method for identifying the B.1.1.7 mutation (N501Y mutation and H69 / V70 deletion) and the effect of this mutation on various biomarkers in inpatients. .. This is the first study to correlate biomarker levels with SARS-CoV-2 mutants.

A total of 253 positive samples were selected for this study, all of which were collected from December to February 2021. In addition to qualitative RT-PCR results, threshold Ct values ​​and patient metadata (age, gender, etc.) were considered. Research. Nasopharyngeal swab (NPS) samples were processed according to the Coronavirus Disease-19 (COVID-19) diagnostic protocol and standard operating procedures.

Subsequently, diagnostic RNA extraction and RT-PCR were performed. Random positive samples were processed for complete viral genome sequencing. This study was conducted by the facility of the COVID-19 UK Genomics UK Consortium (COG-UK) at the University of Birmingham.

The next step was to investigate the presence of the N501Y and ΔH69 / V70 mutations. This was performed by a probe-based melting curve one-step RT-PCR assay using the VirSNiP mutation assay with TibMol (# 53-0780 and # 53-0781). , TIB Molbiol, Berlin, Germany).

Data on biomarkers were obtained from the hospital and anonymized. From 1,112 blood samples, we analyzed the number of hospitalizations and outcomes over time, as well as the mean values ​​for specific biomarkers at the same time and two months ago.

Temporal changes in blood COVID-19 biomarkers during the period from May 10, 2020 to July 3, 2021. The average value expressed as the rate of change from baseline (the average value from October 5 to 18, 2020) is a function of time using measurements at regular time intervals (twice a month). It will be plotted. The biomarkers of interest were measured in the usual biochemical laboratories of UHCW NHS Trust using the CE-marked Elecsys kit from Roche Diagnostics. A total of 1,112 data points were analyzed.

Biomarker values ​​between groups were compared using an independent t-test. When available, B.1.1.7 status and associated biochemical parameters were compared between groups to measure differences between samples. A melting temperature shift of the fluorescence peak from 55.9 to 66.5 ° C (+/- 2.5) indicates the presence of the N501Y mutation. The melting temperature shift for the ΔH69 / V70 mutation was 56.5-63.4 degrees Celsius.

Both assays analyzed robust, reproducible and reproducible properties and analyzed a wide range of primary RNA samples with Ct values ​​between 15 and 28. Of the 253 RNA samples, 235 were successfully implemented with the PCR protocol. The failure rate of the N501Y mutation assay was approximately 7%, while the failure rate of the ΔH69 / V70 assay was 2%.

The major advantage of the method used is that the reaction time for each RT-PCR amplification is short (less than an hour) and results can be produced on the same day. All RNA samples tested positive for N501Y were also observed to be positive for the ΔH69 / V70 mutation.

After identifying the Alpha strain, researchers analyzed the effects on various biomarkers. Three biomarkers, IL-6, BNP, and cTnT, showed a temporary increase in the first half of December 2020, followed by a continuous increase in the second half of January and February 2021. Was noticed. The level of IL-6 was disproportionately high. Similar trends were not significant, but were indicated by markers of cardiac function cTroponin T (cTnT) and NT-pro-BNP. Other inflammatory markers such as CRP, ferritin and LDH did not show the same pattern.

Researchers in the current study used the data to analyze biomarker levels in inpatients with or without the B.1.1.7 / alpha mutant of concern. They focused on a small sample of patients for which biomarkers and clinical outcome data were available (44 patients tested positive for alpha mutants and 39 tested negative). I did. The survivor-to-death ratio was 3: 1 in the alpha variant positive group, compared to 1: 1 in the negative group. Patients were grouped according to their outcome (survival or death) and whether the alpha variant was positive or negative.

In both groups, deceased patients showed higher modified z-scores with some biomarkers, while survivors showed lower or negative z-scores. As mentioned earlier, and as expected, IL-6 showed the most striking difference between alpha mutation-positive deceased patients and survivors, followed by LDH. There was a significant difference in the modified z-scores of most inflammatory biomarkers between the alpha-positive and alpha-negative groups. These include CRP, N / L ratio, pro NTBNP and cTnT.

These results suggest a higher and more potent inflammatory response in deceased patients and activation of multiple biomarkers and pathogenic pathways. LDH and SII levels were higher than the median for the entire group of patients tested positive for alpha mutants, regardless of clinical outcome.

In summary, mutation detection assays may be suitable for the detection of SARS-CoV-2 mutants. Rapid deployment of such tools will help prevent infection of the variant of concern and contain the ongoing COVID-19 pandemic.

*Important Notices

medRxiv Publish preliminary scientific reports that should not be considered definitive as they are not peer-reviewed, guide clinical practice / health-related behaviors, and should not be treated as established information.