Publishable Summary RespViruses
Since it has started the RespViruses project has focussed on novel emerging or old re-emerging viral
pathogens that infect the human respiratory tract and bear the risk of severe infections in the elderly. It
is assumed that severe infections occur mainly due to immunosenescence factors, but so far this
problem was not sufficiently investigated with respect to the challenge of respiratory viruses other than
influenza. In the RespViruses project, hitherto major attention was paid for human metapneumovirus
(HMPV), the respiratory syncytial virus (RSV), human coronavirus NL63, Epstein Barr Virus, and the
human bocavirus.
In a clinical study it was shown by our consortium that severe infections with RSV in the elderly may
be caused by the lack of neutralizing antibodies against this pathogen (figure 1). Previous studies
have shown that virtually all adults have antibodies against RSV thus the data of our consortium are
surprising as it remains unclear why the elderly suffer from life threatening RSV infections (4). The
data lead to the hypothesis that either immunosenescence effects or viral evolution followed by
immune escape or a combination of both occurs in the severe cases of RSV infections in the elderly.
This concept is not really new, but so far has solely been hypothesized for influenza viruses and has
been observed also in the SARS epidemics.
With respect to novel diagnostic tools we were able to develop new assays for testing the RSV serum
status that were successfully tested with a clinical set of patients specimens (Sastre et al., submitted).
In this context the database application developed in the RespViruses project was converted into a
save online tool that is actually in use and will approximately cover more than 2000 datasets on clinical
respiratory infections or immune status against HMPV and other respiratory viruses.
In an ageing murine model of HMPV infections previously published from our consortium (2) we have
started to test the efficacy of DsiRNA that are active against HMPV. We have identified 6 candidate
DsiRNAs that were highly active against HMPV in a novel high throughput assay that allows
identification of potent antivirals (5). Our data were independently verified by another (non EU) group
of scientist working in the same field of research, but this group stopped further development as
intellectual property rights are with one of our consortium partners. Preliminary data are highly
promising and hopefully by the end of the project will result in candidate molecule available for
subsequent clinical testing and application.
Major progress was made by our consortium with respect to the role of human bocavirus as a
pathogen in airway infections. So far, less was known about human bocavirus and most information on
its molecular biology were drawn from sequence alignments and the assumption that human bocavirus
behaves like other parvoviruses despite of the lack of experimental evidence.
The RespViruses consortium was able to contribute with new information to this field. It was shown
that the polarity of the packaged viral DNA that is covered by the viral particle in the majority is of a
negative strand polarity (1). Thereby, the polarity is not influence by the virus subtype. This information
is useful for the development of novel diagnostic tools and antiviral drugs that target the viral nucleic
acid, like e.g. siRNAs. Additionally, and even more exciting, we managed to culture human bocavirus
for the very first time in cell culture. Thereby, both replication kinetics and the viral transcriptome were
analysed and splicing variants were identified (figure 2 + 3; (3)).
HBoV was shown to have a marked tissue tropism that can be used for future gene therapy of lung
tissue tumors. Those recent findings also help to develop diagnostic tools and are essential for
understanding the viral life cycle while contributing to the development of novel antiviral drugs.
Figure 3
References by the RespViruses Consortium
1.
Böhmer, A. S., V; Lüsebrink, J; Ziegler, S; Tillmann, RL; Kleines, M; Schildgen, O. 2009.
Novel application for isothermal nucleic acid sequence based amplification (NASBA). J Virol
Methods 158:199-201.
2.
Darniot, M., C. Pitoiset, T. Petrella, S. Aho, P. Pothier, and C. Manoha. 2009. Age associated aggravation of clinical disease after primary metapneumovirus infection of BALB/c
mice. J Virol.
3.
Dijkman, R. K., S.M.; Molenkamp, R.; Schildgen, O.; van der Hoek, L. 2009. Human
bocavirus can be cultured in differentiated human airway epithelial cells. Journal of Virology
epub ahead of print.
4.
Terrosi, C., G. Di Genova, B. Martorelli, M. Valentini, and M. G. Cusi. 2009. Humoral
immunity to respiratory syncytial virus in young and elderly adults. Epidemiol Infect:1-3.
5.
Schildgen, V., J. Lüsebrink, V. Ditt, R. Tillmann, A. Simon, A. Müller, O. Schildgen 2009
HepG2 cells support RSV and HMPV replication; Journal of Virological Methods, in press.