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The flaviviruses are emerging arthropod-borne viruses that represent an immense global health problem. While effective vaccines exist for three members of the antigenic complex (yellow fever, Japanese encephalitis, and tick-borne encephalitis viruses), safe and effective vaccines for several other flaviviruses of clinical importance, including West Nile and dengue viruses (DENV), remain in development.
Up to now, the serological diagnosis of infection is complicated by the presence of flavivirus cross-reactive antibodies that produce false-positive results, especially in regions where more than one virus is endemic. Commercially available diagnostic reagents for dengue or tick-borne flavivirus infection have been found to cross-react with other flavivirus-positive sera and even with vaccinees´ sera.
The aim of this study is to develop serotype-specific diagnostic assays for the detection of human anti-flaviviral antibodies. Antibodies directed to the envelope glycoprotein (E) are mostly cross-reactive, but those to the domain III (ED3) of the E protein show serotype-specific reactions.
Our research interests are therefore focussed on the EDIII antigen. The EDIII antigens of the 4 DENV, of West Nile virus, Japanese encephalitis virus, tick-borne-encephalitis virus and yellow fever virus are expressed in Escherichia coli, refolded, directly labelled with peroxidase and used in ELISA.
We investigate the potential of the domain III (EDIII) of the envelope protein of different flaviviruses to detect virus-specific antibodies. Only few epitopes are located on the ED3 and highly sensitive assays may be required to detect the small number of human antibodies to this domain. We have established a sensitive immune complex (IC) ELISAs to detect antibodies to the ED3 of TBE virus and West Nile virus. By mixing serum samples with the enzyme-labelled antigen, immune complexes will form that are simultaneously recognized by rheumatoid factor coated microtiter plates.
For the 4 DENV and other flaviviruses we are still evaluating similar assays. The IC ELISA system is especially suitable for studies on the prevalence of flaviviral infections in affected countries.
Highly specific detection of antibodies to tick-borne encephalitis (TBE) virus in humans using a domain III antigen and a sensitive immune complex (IC) ELISA
Ludolfs D, Reinholz M, Schmitz H
J Clin Virol. 2009 Jun;45(2):125-8.
West Nile virus is neutralized by HOCl-modified human serum albumin that binds to domain III of the viral envelope protein E
Vossmann M, Kirst M, Ludolfs D, Schreiber M
Virology. 2008 Apr 10;373(2):322-8.
Reverse ELISA for the detection of anti West Nile virus IgG antibodies in humans
Ludolfs D, Niedrig M, Paweska JT, Schmitz H
Eur J Clin Microbiol Infect Dis. 2007 Jul;26(7):467-73.
Laboratory diagnosis of primary and secondary dengue infection
Schilling S, Ludolfs D, Van An L, Schmitz H
J Clin Virol. 2004 Nov;31(3):179-84