Laboratory Investigation of SARS COV-2 Virus Infection

PCR Molecular Detection

With many years of experience in Molecular Diagnostics and specialization in infectious agents (with 3 international patents and publications), at Locus Medicus laboratories, the molecular test for the detection of the new SARS-CoV-2 coronavirus strain is performed with an accreditation certificate, (Hellenic Accreditation system, Certificate No.621, ELOT EN ISO 15189).

The detection process is performed in Level II Biosafety facilities, strictly following the WHO / CDC1,2 protocols. RNA detection of the new coronavirus strain RNA with reverse transcription and real-time polymerase chain reaction (RT) has been designed according to published WHO / CDC guidelines (

The molecular PCR assay method is based on the detection of viral particles and ensures guaranteed assay reliability.

In addition to detecting the SARS Cov-2 virus in our laboratories, the strain is now standardized, including the Omicron strain, as well as semi-quantitative information on the size of the viral load. Thus, we can determine the clinical course of the patients, if they are in the initial phase of the disease, its prevalence, its remission, or its relapse.

All molecular tests are performed individually.

For the polymerase chain reaction (PCR) test the sample is taken from a nasopharyngeal smear.

Every day we receive samples from large companies, hospitals, microbiological laboratories, cruise ships, sports clubs as well as citizens who come to the specially designated area of our company premises, without waiting time and without coming into contact with other people (drive in) in conditions of absolute safety, safeguarding the diagnostic success.

  • Results are issued on the same day.
  • For travelers, the answer is issued in English.
  • Home sampling.
    (Pricing is charged with a reasonable commuting fee, proportional to the distance from our center).
  • All mutant types of the virus are identified by the molecular method used.
  • Each positive result can be commented on by evaluating the course of the disease based on the semi-quantitative assessment of viral load.

Rapid Test

In addition to the molecular detection method, rapid tests and antibody tests are performed in LOCUS-MEDICUS laboratories.

Rapid antigen tests for COVID-19 (Ag-RDT) are immunochromatography-based. In the case of SARS-CoV-2, the target is often a nucleocapsid (N) protein of the virus, as it is abundant in the virus and sufficiently specific for SARS-CoV-2. It is one of the 4 most important structural proteins and is involved in the replication, transcription, and binding of the viral genome.

Rapid antigen tests have helped to reduce the COVID-19 pandemic as they are extremely effective 3 – 10 days after infection, when the patient is contagious and often still asymptomatic. Over the months there has been a remarkable improvement in the sensitivity of the method. We are very pleased to see rapid tests by specific companies to detect the virus in samples, in which the molecular method detected a very small viral load.

It’s the fastest way to do a Covid test economically and reliably, as the results are available within an hour.

Our company has evaluated the sensitivity and specificity of at least 15 different Rapid Test reagents with noted differences between them. The most reliable ones have been selected from us after a comparative test.

Detection of IgM and IgG antibodies

Detection of IgM and IgG antibodies against SARS COV-2 protein S1 (spike).

The test is useful for checking and monitoring the antibodies that have developed in both patients who have been infected with the virus and those who have been vaccinated. It is done by blood sampling.

Following infection and proliferation of the virus, the body produces antibodies that counteract the prevalence of the virus in the individual, as well as its infectivity in other individuals. IgM antibodies against both the nucleocapsid (N) and the spike (S) are detected 5-7 days after exposure to the virus. IgGs, both N and S, are detected 2-3 weeks after exposure to the virus and remain stable for a long time. However, a negative result, does not exclude the possibility of exposure of the person or his infection with the virus. A negative result may occur if the antibody concentration is below the test detection thresholds or if antibodies are not yet present at the stage at which the test was performed.

The automated immunoassay referred to involves the quantification of antibodies that develop against the binding site at the SARS COV-2 S1 protein (spike) RDP receptor and uses chemiluminescence microparticle technology (CMIA).

In our laboratory, a positive value is considered > 50 AU/ml. But the vaccine, as well as the recovery from the disease, is commonly accepted that they establish immunity, either through the production of antibodies (which the test measures), or through other mechanisms of the body’s defense. Therefore the presence of antibodies informs us about the development of immunity (existence of protection), but, in order to formulate time margins, we must wait for the formulations of the official reference centers. We recommend the SARS-COV-2 Antibody Detection Test approximately 20 days after the PCR is negative or after the administration of the second dose of vaccine.

The examination is characterized by a high degree of sensitivity and specialization. The results are issued on the same day.


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