Search

US-20260125772-A1 - Biomarkers for Long COVID

US20260125772A1US 20260125772 A1US20260125772 A1US 20260125772A1US-20260125772-A1

Abstract

The present invention relates to a method for in vitro diagnosis of Long COVID in a subject, wherein the method comprises the following steps: a) providing a biological sample obtained from the subject; b) measuring the levels of circulating cell-free mitochondrial DNA (ccf-mtDNA) in said sample; and c) comparing the levels of ccf-mtDNA measured in step b) with a reference, wherein a decrease in the levels of ccf-mtDNA in said sample relative to the reference is indicative of Long COVID diagnosis.

Inventors

  • Tibor PANKOTAI
  • László TISZLAVICZ
  • Barbara Nikolett BORSOS

Assignees

  • Szegedi Tudományegyetem

Dates

Publication Date
20260507
Application Date
20251107
Priority Date
20241107

Claims (10)

  1. 1 . A method for in vitro diagnosis of Long COVID in a subject, wherein said method comprises the following steps: a) providing a biological sample obtained from the subject, b) measuring the levels of circulating cell-free mitochondrial DNA (ccf-mtDNA) in said sample, c) comparing the levels of ccf-mtDNA measured in step b) with a reference, wherein a decrease in the levels of ccf-mtDNA in said sample relative to the reference is indicative of Long COVID diagnosis.
  2. 2 . The method according to claim 1 , wherein the circulating cell-free mitochondrial DNA comprises at least one mitochondrial DNA segment or mitochondrial gene, wherein the ccf-mtDNA is selected from MTATP6-, MTCYTB-, MTND1-, MTND4-, and MTND5-specific DNAs.
  3. 3 . The method according to claim 1 , wherein the ccf-mtDNA comprises at least two mitochondrial DNA segments or mitochondrial genes selected from the group comprising MTATP6-, MTCYTB-, MTND1-, MTND4-, and MTND5-specific DNAs.
  4. 4 . The method according to claim 1 , wherein the ccf-mtDNA comprises five different mitochondrial DNA segments or mitochondrial genes, wherein the five mitochondrial DNAs are MTATP6-, MTCYTB-, MTND1-, MTND4-, and MTND5-specific DNAs.
  5. 5 . The method according to claim 2 , wherein a decrease in the levels of at least one mitochondrial DNA in said sample relative to the reference is indicative of Long COVID diagnosis.
  6. 6 . A method of in vitro monitoring treatment of Long COVID in a subject, wherein said method comprises the following steps: a) providing at least two biological samples obtained from the subject undergoing Long COVID treatment, wherein one sample is obtained prior to the start of treatment and the other sample(s) are obtained after the treatment has begun, b) measuring the levels of circulating cell-free mitochondrial DNA (ccf-mtDNA) in the sample obtained prior to the start of the treatment, thereby obtaining a baseline, c) measuring the levels of circulating cell-free mitochondrial DNA (ccf-mtDNA) in the sample(s) obtained after the treatment has begun, d) comparing the levels of ccf-mtDNA measured in step c) with the baseline obtained in step b), wherein an increase in the levels of ccf-mtDNA in the sample(s) obtained after the treatment has begun, relative to the baseline, indicates an effective Long COVID treatment.
  7. 7 . The method according to claim 1 , wherein the biological sample is selected from blood, serum, plasma, or cerebrospinal fluid.
  8. 8 . The method according to claim 6 , wherein the biological sample is selected from blood, serum, plasma, or cerebrospinal fluid.
  9. 9 . The method according to claim 6 , wherein said ccf-mtDNA is selected from MTATP6-, MTCYTB-, MTND1-, MTND4-, and MTND5-specific DNAs.
  10. 10 . A kit for diagnosing Long COVID, comprising primers for ccf-mtDNA, wherein the primers are for MTATP6-, MTCYTB-, MTND1-, MTND4-, and/or MTND5-specific DNA(s).

Description

This application claims priority to Hungarian Application No. P2400507 filed Nov. 7, 2024, and Hungarian Application No. P2400511 filed Nov. 8, 2024, which are both herein incorporated in their entirety by reference. The content of the sequence listing named 124512-00066_sequence_listing_edit1.xml, which is 11,181 bytes in size was created on Nov. 6, 2025, and is incorporated herein by reference in its entirety. FIELD OF THE INVENTION The present invention relates to methods for in vitro diagnosis of Long COVID in a subject, using quantified or detected biomarkers in a biological sample. In particular, the invention relates to a method for in vitro diagnosis of Long COVID in a subject, wherein said method comprises the following steps: a) providing a biological sample obtained from the subject; b) measuring the levels of circulating cell-free mitochondrial DNA (ccf-mtDNA) in said sample; and c) comparing the levels of ccf-mtDNA measured in step b) with a reference, wherein a decrease in the levels of ccf-mtDNA in said sample relative to the reference is indicative of Long COVID diagnosis. TECHNICAL BACKGROUND The emergence of Coronavirus Disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has precipitated a global health crisis with enduring implications. As of the latest updates, COVID-19 has affected over 775 million individuals worldwide, resulting in more than 7 million deaths across various countries and territories [1]. The mortality rate for COVID-19 differs significantly by age, with older adults, especially those with underlying health conditions, experiencing disproportionately higher rates of fatalities [2-5]. The pandemic has seen multiple waves, driven by the emergence of virus variants, each varying in transmissibility and virulence [6-7]. Despite extensive vaccination efforts, which have seen billions of vaccine doses administered globally, the virus continues to impact populations, healthcare systems, and economies. While the majority of affected individuals recover from the acute respiratory syndrome within a few weeks, approximately 30-70% of those infected experience persistent and debilitating symptoms collectively termed Long COVID, post-COVID-19 syndrome, or Post-Acute Sequelae of SARS-CoV-2 infection (PASC) [3, 8-26]. Chronic fatigue is consistently identified as the most common and debilitating symptom reported by survivors, as demonstrated by various cross-sectional and cohort studies [18, 27-31]. Individuals affected by Long COVID often experience a broad range of additional symptoms, including dyspnea, joint pain, sleep problems, mood disorders such as depression and anxiety [32], headaches, dizziness, cognitive issues commonly referred to as “brain fog”, and cardiac symptoms [18]. These symptoms can persist for months and significantly impair quality of life. The National Institute for Health and Care Excellence categorizes PASC as ongoing symptomatic COVID-19 for individuals whose symptoms persist between four and twelve weeks following the initial onset of acute symptoms or as post-COVID-19 syndrome for those whose symptoms continue beyond twelve weeks [18, 33]. In contrast, the World Health Organization describes PASC as a condition affecting individuals with a suspected or confirmed SARS-CoV-2 infection who experience lasting symptoms for a minimum of two months, and where these symptoms cannot be attributed to another underlying medical condition [9, 34]. Long COVID presents a complex clinical picture that implicates multiple organ systems. Emerging evidence suggests mitochondrial dysfunction as a central component of this syndrome [35-49]. Mitochondria, essential for energy production and cellular metabolism, are particularly vulnerable to SARS-CoV-2 infection [36]. The virus may hijack and reprogram mitochondrial function or inflict direct damage through various mechanisms during and potentially after infection [36]. Such disruptions lead to altered energy metabolism, which is believed to contribute to the fatigue, cognitive impairments, and muscular weaknesses commonly observed in Long COVID patients [35, 36]. Siekacz et al. [83] investigated the association between post-COVID-19 pulmonary complications and mitochondrial regulatory proteins in the context of oxidative stress. They found that serum concentrations of mitochondrial regulatory proteins (e.g. PINK1, DNM1L, MFN2) were significantly higher in the long-term pulmonary complications group. They concluded that SARS-CoV-2 infection could be involved in mitochondrial imbalance via PINK1, DNM1L, and MFN2 dysregulation, however, they suggested only that TNF-α might be a potential predictor of pulmonary complications. US20240219385A1 discloses a method of diagnosing or classifying a subject as having a chronic or long-term infection of a virus (e.g. SARS-CoV-2), which comprises determining the level of one or more biomarkers in a biological sample obtained from a subject.