Hauke Walter Viral fitness Terminological problems What is viral - - PDF document

Viral fitness Hauke Walter

Terminological problems

• What is viral fitness?

The virus adapts due to selective pressure. Therefore the most fit virus is always the majority, because it has the biggest advantage according to the actual pressure(s). Resistance has to be understood as a part of viral fitness.

Genotype - clinical response

virologic response genotypic changes phenotypic resistance

replicative capacity ? antiretroviral therapy immune response drug level

virological and immunological therapy failure

40% 40% 5% 15%

treatment failure: effective therapy: VL Cd4

+

Cd4

+ VL

Cd4

+ VL

Cd4

+ VL

• L. Perrin and A. Telenti: HIV Treatment Failure: Testing for HIV

Resistance in Clinical Practice; Science, Vol. 280 June 1998

Less Pathogenic?

new replicative capacity (RC) assay

50µl viral SN

1.93 5.17 2.69 19056 1.39 1.39 1.39 1.39

• 2

2 4 6 8 10 12 14 16 18 20 1 4 10 27 72 192 514 1376 3687 9878

1/dilution (increase of infectious dose)

SEAP activity /1000

NL4-3

saturation

determination of replicative capacity (RC)

background background

SEAP activity NL4-3 of 30 different IDs day3

0,000 5,000 10,000 15,000 20,000 25,000 1000 2000 3000 4000 5000 6000

1/ dilution factor

SEAP activity SEAP activity NL4-3 of 30 different IDs day6

0,000 5,000 10,000 15,000 20,000 25,000 100 200 300 400

1/ dilution factor

SEAP activity

9.726 434.8 9.958 46.9

NL4-3 solver NL4-3 solver

saturation saturation

• determination of

the produced infectivity

• by infection of new cell

cultures 1:1 after 3 days

• Same curve but other ID

(according to day 0)

• dependent on viral growth

behaviour

example: relative RC of different viruses

• small interassay variability: 1.27-fold

day 3 day 6 increase day3/day6 RC NL4-3 434.8 46.9 9.27 100% virus 1 990.2 183.8 5.39 58% virus 2 459.9 233.3 1.97 21%

summary

– RC determination upsides of competitive replication assays is biased by – cell culture saturation – Differences in the RC in order to find ONE infectious dose fitting for all viruses –Variability of the assays determining the infectivity in cell culture supernatants (higher than the differences of RC  ) – Combining the determination of supernatant infectivity and RC in the same assay was helpful – Results were obtained detecting quantitavely the production of new infective particles over time

Acknowledgements

Institute for Bioinformatics (Saarbrücken, Germany) : Tobias Sing André Altmann Hendrik Weisser Thomas Lengauer Institute for Virology (Erlangen, Germany): Monika Tschochner Sabine Wittmann Christiane Paatz Tim Engel Wolfgang Ruhland Bernhard Fleckenstein Institute for Virology (Cologne, Germany): Rolf Kaiser Jens Verheyen Martin Daeumer Lots of others.. Vivantes Auguste-Viktoria Hospital, Berlin, Germany

• C. Weber
• H. Stocker
• M. Kurowski
• K. Arasteh