The heterogeneity of individual immune response leads to a low correlation between humoral immune measurements with the magnitude of the T cell response. SARS-CoV-2-specific T cells may be present in the absence of antibodies, and antibody and T cell responses are independent in magnitude and in persistence during the memory phase of the immune response¹. This is also true for several vaccine classes (mRNA- and protein-based) that might lead to a different humoral and cellular response, and ultimately a different protection against the SARS-CoV-2. Data from preclinical models and humans show that T cells protect against severe COVID-19 disease and reduce viral spread⁴.

As the distribution of infection and vaccines mitigates the pandemic, vaccine efficacy and the duration of protective immunity will need to be systematically evaluated and monitored by T cell specific reactivity against SARS-CoV-2.

Hyris offers an innovative solution to evaluate T Cells reactivity against SARS-CoV-2, leveraging the unique characteristics of the Hyris System^TM:

• Validated in Real-Time PCR by direct amplification - without DNA or RNA extraction on blood samples
• Flexible throughput thanks to different proprietary cartridge formats (16 or 36 wells)
• Portability and scalability using HYRIS bCUBE^TM
• Automatic interpretation of results and advanced data management

Hyris T cell test ultimately helps to evaluate the protection level against SARS-CoV-2 given by a previous infection and/or vaccination, and consists of two separated kits:

1. the XTACT SCV2 T Activation kit (pre-analytical phase)
2. the bKIT^TM Immunofinder dqTACT MS (analytical phase)

The specific peptide pool of SARS-CoV-2 Spike and Nucleocapsid proteins (i.e. Pool ONE and Pool B of XTACT SCV2 T Activation kit) are used to stimulate the T cells in the pre-analytical phase. The mRNA of CXCL10 produced by monocytes is then analyzed by RT-qPCR as readout of T cell responsiveness. Relative CXCL10 mRNA levels in Pool ONE and Pool B are compared to the control, in which T cells are not stimulated (Pool NEG). 

The RT-qPCR can be performed by direct amplification on whole blood and without nucleic acid purification.

bKIT^TM Immunofinder dqTACT MS sensitivity (determined by the LoD) is 10³ copies/µl of CXCL10 mRNA, calculated by the regression curve approach.

1. Tarke A. et al., SARS-CoV-2 vaccination induces immunological T cell memory able to cross-recognize variants from Alpha to Omicron, Cell (2022) 185(5) 847-859.e11
2. Schwarz M. et al., Rapid, scalable assessment of SARS-CoV-2 cellular immunity by whole-blood PCR, Nature Biotechnology (2022)
3. Geers D. et al., SARS-CoV-2 variants of concern partially escape humoral but not T-cell responses in COVID-19 convalescent donors and vaccinees, Science immunology (2021) 6(59)
4. Diani S. et al., SARS-CoV-2—The Role of Natural Immunity: A Narrative Review, Journal of Clinical Medicine (2022) 11(21) 6272