Biomedical subjects

E Attakpah

Publications and source records attributed to E Attakpah.

3 recordsLinked to original sources

PubMed1998

Vaccination against tick-borne encephalitis virus, a flavivirus, prevents disease but not infection, although viremia is undetectable.

By adoptive transfer of sera or immunoglobulin preparations, vaccine-induced protection against TBEV has been demonstrated to be mediated by antibodies to the surface protein of TBEV, glycoprotein E. Nevertheless, the mechanism of vaccine-induced protection against TBEV remains unclear. Protection by E antibodies without in vitro neutralization was shown by one group, whereas others found a correlation between protection in vivo and neutralization in vitro. Here, the authors confirm in a mouse model of tick-borne encephalitis (TBE) that immunization with the whole-killed virus vaccine protects mice against a subsequent challenge with a highly lethal dose of virus, i.e. 250 LD50 doses. Vaccine-induced immunity, however, is not completely neutralizing as demonstrated by the development of immune responses to a non-structural virus protein absent from the vaccine, yet expressed in the course of virus replication. Antibodies specific for the non-structural protein 1 (NS1) and cytotoxic T-cells could be detected after, but not prior to, virus challenge of vaccinated animals, establishing that protection by this highly effective vaccine is not equivalent with complete neutralization of the challenge virus.

Adoptive Transfer↗

PubMed1997

Detection of tick-borne encephalitis virus by sample transfer, plaque assay and strand-specific reverse transcriptase polymerase chain reaction: what do we detect?

Experimental inoculation of mice provides a well characterized model for studying infection with tick-borne encephalitis virus (TBEV), a flavivirus pathogenic for humans. Conflicting data on the kinetics of viremia and the development of virus titers in the brain, however, were only recently shown to have resulted from the use of assay systems with different levels of sensitivity in the titration of TBEV, i.e. plaque assay or sample transfer into naive recipient mice. Theoretically, RT-PCR could extend further the detectability to antibody-neutralized virus and when undertaken strand-specifically discriminate active replication from the mere presence of TBEV. We have compared the conventional methods for detection of TBEV with a newly devised RT-PCR method. As expected, RT-PCR, in contrast to the infectivity assays, detected antibody-neutralized virus. Furthermore, the mere presence or active replication of the virus could be differentiated by strand-specific RT-PCR. Plaque assay and sample transfer, in contrast, both detected only infectious virus. However, whereas sample transfer provides higher sensitivity for detection of TBEV from solid organs, the plaque assay is less costly and considering animals welfare more convenient. Thus, the newly devised method may allow the resolution of unanswered questions, while both the traditional infectivity assays retain their benefits in certain situations.

Animals↗

PubMedDate not supplied

Passive immunization reduces immunity that results from simultaneous active immunization against tick-borne encephalitis virus in a mouse model.

Concomitant administration of an antigen and antibodies of the respective specificity has been shown to result in reduced levels of actively produced antibodies. This has also recently been observed in a clinical trial on simultaneous passive and active immunization against tick-borne encephalitis virus (TBEV). In the current study the influence of simultaneous passive and active immunization on vaccine induced protective immunity against TBEV has been evaluated in a mouse model. Two immunizations with licensed whole-killed TBEV vaccines gave close to complete protection. Administration of human or mouse TBEV antibodies together with the first vaccine dose resulted in a significant reduction of vaccine induced protection against TBEV challenge. This effect was even more pronounced than that observed earlier on the levels of vaccine induced antibody.

Animals↗