Torque-Teno virus to optimize timing of vaccination against severe acute respiratory syndrome coronavirus 2 in solid organ transplant recipients

Torquetenovirus Loads in Peripheral Blood Predict Both the Humoral and Cell-Mediated Responses to SARS-CoV-2 Elicited by the mRNA Vaccine in Liver Transplant Recipients

Three years into the COVID-19 pandemic, mass vaccination campaigns have largely controlled the disease burden but have not prevented virus circulation. Unfortunately, many immunocompromised patients have failed to mount protective immune responses after repeated vaccinations, and liver transplant recipients are no exception. Across different solid organ transplant populations, the plasma levels of Torquetenovirus (TTV), an orphan and ubiquitous human virus under control of the immune system, have been shown to predict the antibody response after COVID-19 vaccinations. We show here a single-institution experience with TTV viremia in 134 liver transplant recipients at their first or third dose. We found that TTV viremia before the first and third vaccine doses predicts serum anti-SARS-CoV-2 Spike receptor-binding domain (RBD) IgG levels measured 2-4 weeks after the second or third dose. Pre-vaccine TTV loads were also associated with peripheral blood anti-SARS-CoV-2 cell-mediated immunity but not with serum SARS-CoV-2 neutralizing antibody titers.

Torque teno virus and cancers: current knowledge

Aim: The aim of this systematic review is to assess the current knowledge about the relationship between Torque teno virus (TTV) and cancer in different settings. Methods: A systematic search was conducted in Medline via PubMed, Embase and Cochrane Library from the inception to the end of January 2023. Results: 34 articles were included in the qualitative synthesis of this review and 2145 patients with solid tumors have been analyzed. The most prevalent cancer types were hepatocellular carcinoma (HCC) and lung cancer. Conclusion: TTV has proven its role as a marker of functional immune competence in the setting of hematopoietic stem cell transplantation (HSCT), but in the oncological field is yet to be defined.

TTV viral load as a predictor of antibody response to SARS COV-2 vaccination

The measure of torquetenovirus (TTV) viremia is widely recognized as an optimal biomarker of an individual immune status. In the context of COVID-19, the predictive role of TTV load with regard to vaccine response has also been demonstrated, suggesting other intriguing applications for this widespread anellovirus.

Torquetenovirus viral load is associated with anti-spike antibody response in SARS-CoV-2 mRNA BNT162b2 vaccinated kidney transplant patients

INTRODUCTION

Kidney transplant patients (KT) are at high risk for severe COVID-19 and presented attenuated antibody responses to vaccination when compared to immunocompetent individuals. Torquetenovirus (TTV) has recently gained attention as a potential surrogate marker of the net state of immunosuppression. We evaluated the association between pre-vaccination TTV viral load and anti-spike total antibody response to SARS-CoV-2 vaccination in KT.

MATERIAL AND METHODS

The 114 adult KT recipients enrolled in this prospective single-center cohort study received two doses of SARS-CoV-2 mRNA BNT162b2 vaccine. Serum samples were collected immediately before vaccination at the days when patients received both the first (T0) and the second dose (T1) and 16-45 days after the second dose (T2). Primary endpoint was the development of anti-spike total antibodies after vaccination. Demographic, clinical, and laboratorial parameters were compared between patients with and without detectable SARS-CoV-2 antibodies at T2.

RESULTS

Ninety-nine patients (86.8%) were naïve for SARS-CoV-2 before vaccination. Fifty-six (56.6%) patients developed anti-spike total antibodies at T2. The use of mTOR inhibitors was associated with a favorable response (p = .005); conversely, mycophenolic acid (MPA) was associated with a negative response (p = .006). In a multivariable model, the presence of TTV at T0 ≥ 3.36 log₁₀ cp/ml was associated with unfavorable vaccine response (OR: 5.40; 95% CI: 1.47-19.80; p = .011), after adjusting for age and eGFR at T0.

CONCLUSIONS

Higher TTV viral loads before vaccination are associated with reduced anti-spike total antibody response in SARS-CoV-2 mRNA BNT162b2 vaccinated KT patients. The association between TTV viral load and vaccine response may be an added-value in the optimization of vaccination regimens in KT.

Biomarker-Based Assessment for Infectious Risk Before and After Heart Transplantation

Purpose of Review

Survival outcomes for heart transplant recipients have improved in recent decades, but infection remains a significant cause of morbidity and mortality. In this review, we discuss several biological markers, or biomarkers, that may be used to monitor immunologic status in this patient population.

Recent Findings

While modest, data on the utility of immune biomarkers in heart transplant recipients suggest correlation between low level of immune response and increased infection risk. More novel assays, such as the detection of circulating levels of pathogen cell-free DNA in plasma and the use of Torque teno virus load as a surrogate for net state of immunosuppression, have potential to be additional important biomarkers.

Summary

Biomarker approaches to individualize immunosuppression therapy among heart transplant recipients is a promising area of medicine. However, additional studies are needed to inform the optimal protocol in which to incorporate these biomarkers into clinical practice.