Serologie

The serology unit is responsible for the diagnosis of viral infections on basis of the demonstration of virus specific antibodies in patient sera.

Traditionally paired serum samples are used to show seroconversion, thus confirming recent infection. The demonstration of specific IgM or IgA serum antibodies allows the diagnosis of several virus infections in the acute stage, using one serum sample only. For identification of individuals with certain persistent viruses like HIV-1, HIV-2 and HTLV, serum antibody detection is the method of choice. Furthermore, monitoring of kinetics of serum antibody levels against different viral antigens during infection may have direct diagnostic, prognostic and therapeutic implications.

During the last two years, special attention has been given to the development of user friendly assays, which are more specific and sensitive than the classical serological assays. Many of these have now been implemented in the routine diagnostic setting. In addition, several serological assays have been developed and introduced to diagnose “exotic” virus infections. This has become increasingly relevant over the past decade due to increased travel activities.

Developments

  • Hepatitis serology: Since our hospital is a reference center for treatment of chronic viral hepatitis, the monitoring of the effect of treatment is essential in patient management. Aside from several quantitative molecular techniques, serologic tests can be used. For this purpose a quantitative HBeAg en HBsAg assay were developed using a standard based on the Paul Ehrlich standard.
  • Respiratory infections: Several years ago our laboratory still performed complement fixation tests to diagnose an infection with influenza virus, parainfluenza virus or adenovirus. The disadvantages of this CF assays are that they are quite laborious, are not that sensitive and always require two consecutive serum samples to diagnose a significant titer rise, indicating a recent infection. An IgA-capture ELISA was developed and evaluated together with an IgG ELISA for its value in diagnosing a respiratory viral infection using only one serum sample. The promising result (1) led to the abolishment of the CF technique. Future developments: For influenza A and B virus and coronavirus, nucleoproteins are in production using a baculo-virus expression system. These nucleoproteins will be used to develop (corona) or improve (influenza) an IgA-capture ELISA for rapid serological diagnosis of these infections.
  • Herpes viruses: A fully automated immuno-assay for HSV-2 specific antibodies was evaluated for its sensitivity and specificity comparing this assay with one immunoblot assay (RIBA) and two other EIAs (2, 3). The sensitivity and specificity were 100 % and 97.1 % respectively. This assay can be a useful tool for seroepidemiological studies. Future developments: Epstein Barr virus serology can be difficult to interpret. Therefore, several EIAs will be compared with a new system, the coupled particle light scattering assay, for their value in diagnosing both primary and secondary EBV infections.
  • Projects and collaborations: Rotterdam cohort of homosexual males: Recently a prospective study has been initiated by the STD clinics of our hospital to study the incidence and prevalence of HIV infections and other STDs in a population of homosexual men. The influence of sexual behavior and setting on this incidence will be studied. HIV patients co-infected with HBV and/or HCV: Due to efficient antiretroviral combination treatment, HIV infected individuals have a prolonged survival. Therefore, chronic infections, such as hepatitis B and C infections play a more prominent role in morbidity in this patient group. A retrospective study in collaboration with the clinicians has been performed to study the prevalence of HBV and HCV co-infections in our hospital.