Virus reactivation EBV, CMV, VZV (ELISpot)

Epstein-Barr virus (EBV), cytomegalovirus (CMV) and varicella-zoster virus (VZV) belong to the herpes virus family. Most adults have been infected with one or more of them in the course of their lives. After the first infection, these viruses remain in the body in a dormant form for life. The viral reactivation screen uses the ELISpot method to examine whether the immune system is currently working actively against these three viruses. This requires living immune cells from citrate blood, which must reach the laboratory quickly – which is why express shipping is needed. In the test catalogue the test is listed as the viral CFS and the viral PCS reactivation screen.

How herpes viruses lie dormant in the body and wake up again

Each of the three viruses has its hiding place: EBV rests in B lymphocytes, CMV in monocytes and their precursor cells in the bone marrow, VZV in the nerve ganglia next to the spinal cord and on the cranial nerves. In this dormant phase (latency), the viruses produce hardly any components that the immune system recognises. Specialised T cells keep them permanently in check: as soon as an infected cell produces viral components again, they recognise and remove it. If this control weakens – for example with severe physical or psychological stress, other infections, medicines that dampen the immune system or in older age – the viruses can become active again and multiply. This is called reactivation.

What the ELISpot measures for EBV, CMV and VZV

ELISpot stands for enzyme-linked immunospot. In the laboratory, T cells from the blood are brought together with components of the three viruses. T cells that recognise these components release messengers such as interferon-gamma. Each responding cell leaves a coloured spot on a special membrane, which is counted. Unlike antibodies in the blood, which often persist for years after an infection, the ELISpot shows the current cellular immune response. If components are used that the virus produces only in its active replication phase, a strong response indicates that the immune system is currently dealing with a virus that has become active again.

Virus reactivation detectable – what happens in the body?

When a virus becomes active again, it multiplies in its host cells and releases new virus particles. The immune system responds with T cells and messengers such as interferons, which act throughout the body: exhaustion, feeling unwell, swollen lymph nodes, sore throat or mild fever may follow. With EBV, the lymph nodes and spleen can enlarge. VZV reactivation often shows as shingles with burning pain and blisters along a nerve, but can also occur without skin signs. In ME/CFS and long/post-COVID, signs of EBV reactivation have been observed more often in studies; whether they trigger the symptoms or result from weakened immune control is still debated.

No virus reactivation detectable – what does it mean?

If the ELISpot shows no notable response to components of the active viral phase, this speaks against the immune system being intensively engaged with a reactivation of EBV, CMV or VZV at the time of the blood sample. The viruses may nevertheless be present in dormant form – this is the case in most adults and is unremarkable in itself. Reactivations can occur in phases, so the result reflects a single point in time. Because the test depends on living cells, transport time and sample quality also influence the result. Together with antibody findings and the values of the autoantibody screen, a more complete picture emerges.

The interpretation is given in your report.