Transcript Is Coinfection with Herpesvirus Responsible for Acyclovir

Is Coinfection with Herpesvirus Responsible for Acyclovir Phosphorylation in Enterovirus Treatment?
Angela Sowers
Department of Biological Sciences, York College of Pennsylvania
Review of Literature
•Acyclovir (ACV) is a guanine-like compound used
to inhibit DNA polymerase, an enzyme necessary
for DNA biosynthesis.
Research Design
Expected Results
Infect tonsillar tissue blocks with
either EV-71 or HHV-6B
Determine viral load in each
tissue block (Real-Time PCR)
http://tpe-u.com/tpu/emea/en/aboutus/contact_persons/docId-2474054/Ansprechpartner_APAC.html?docPart=0
*Asia –Pacific region is in red
Introduction
•In recent years, numerous outbreaks of enterovirus 71
(EV 71) have occurred in the Asia-Pacific region (Qui
2008).
•EV 71 can result in HFMD (hand-foot-and-mouth
disease), encephalitis, aseptic meningitis, upper
respiratory illnesses, and paralysis (Shors 2009).
•There is no FDA-approved antiviral for the treatment
of enteroviruses (Chen et al. 2008).
•Acyclovir, an antiviral used to treat herpesvirus, has
successfully treated patients with enterovirus in
studies conducted by Faulkner et al. (2005) and Shelley
et al. (1988).
•Acyclovir is activated by thymidine kinase, an enzyme
found only in herpesvirus; enterovirus does not code
for a thymidine kinase.
•Recent studies have been conducted concerning
acyclovir treatment for HIV, in which researchers
showed that acyclovir only inhibited HIV replication in
patients who were coinfected with herpesvirus.
•It is possible that patients with enterovirus may be
successfully treated with acyclovir if they are already
infected with herpesvirus.
Objectives
•To determine whether or not EV 71
phosphorylates acyclovir
•To determine if acyclovir phosphorylated by
HHV-6B (human herpesvirus 6B) inhibits EV
71 replication
http://www.scd.co.kr/upload/medicine/
http://en.wikipedia.org/wiki/Aciclovir
•Initially, acyclovir is phosphorylated by a viral
thymidine kinase (found in herpesvirus) and becomes
acyclovir monophosphate (ACV-MP).
•ACV is further phosphorylated by host cell enzymes,
forming acyclovir triphosphate (ACV-TP); this is the
active form that will incorporate itself into the DNA
and prevent replication (Elion 1993).
Set up tissue cultures: EV-71 only,
HHV-6B only, coinfected culture
(EV-71 & HHV-6B)
Treat all tissue cultures with ACV
(4.8 µg/day for 3 days)
Expected Conclusion
Monitor ACV phosphorylation by
detecting the presence of ACV-MP
and ACV-TP (LC-MS/MS)
Monitor EV-71 replication in
coinfected culture (Real-Time PCR)
Expected Results
•Recently, Lisco et al. (2008) tested the effectiveness
of acyclovir treatment on HIV by treating infected
tonsil tissue received from donors. They discovered
that acyclovir inhibited HIV replication in these
tissues. The researchers knew that HIV does not
code for a thymidine kinase. Noting this, they tested
their tonsil tissues for herpesvirus (HHV’s 1-8) and
found that the donated tonsil tissues were all
infected with at least one form of herpesvirus (mostly
HHV-6). The researchers concluded that HHV must
be present for successful acyclovir treatment of HIV.
Figure 2. Example of LC-MS/MS (Liquid Chromatography Tandem Mass
Spectrometry) plot showing both the presence of ACV-MP and ACV-TP. These
peaks are only expected in HHV-6B cultures and the coinfected cultures because
ACV must be monophosphorylated by a viral thymidine kinase. Cellular enzymes
take over after initial phosphorylation.
HHV-6B must be present in order to
phosphorylate acyclovir and cause it
to inhibit EV-71 replication. Clinically,
this would mean a patient would have
to be infected with herpesvirus for
successful treatment of enterovirus
with acyclovir.
Literature Cited
Chen, T., Weng, K., Chang, S., Lin, J., Huang, P. and Shih, S. 2008. Development of
antiviral agents for enteroviruses. Journal of Antimicrobial Chemotherapy 62: 11691173.
Elion, G.B. 1993. Acyclovir: discovery, mechanism of action, and selectivity. Journal of
Medical Virology Supplement 1: 2-6.
Faulkner, C.F., Godbolt, A.M., DeAmbrosis, B. and Triscott, J. 2005. Hand, foot, and mouth
disease in an immunocompromised adult treated with aciclovir. Australasian Journal of
Dermatology 44: 203-206.
Lisco, A., Vanpouille, C., Tchesnokov, E.P., Grivel, J., Biancotto, A., Brichacek, B., Elliott, J.,
Fromentin, E., Shattock, R., Anton, P., Gorelick, R., Balzarini, J., McGuigan, C., Derudas,
M., Götte, M., Schinazi, R.F. and Margolis, L. 2008. Acyclovir is activated into a HIV-1
reverse transcriptase inhibitor in herpesvirus-infected human tissues. Cell Host and
Microbe 4: 260-270.
Monpoeho, S., Mignotte, B., Schwartzbrod, L., Marechal, V., Nicolas, J.C., Billaudel, S. and
Ferre, V. 2000. Quantification of enterovirus RNA in sludge samples using single tube
real-time RT-PCR. Biotechniques 29: 88-93.
Qui, J. 2008. Enterovirus 71 infection: a new threat to global public health? The Lancet
Infectious Diseases 7: 868-869.
Shelley, W.B., Hashim, M. and Shelley, E.D. 1996. Acyclovir in the treatment of hand-footand-mouth disease. Cutis 57: 232-234.
Shors, T. 2009. Understanding Viruses. Jones and Bartlett Publishers, Sudbury, MA.
Figure 3: Example of a real-time PCR plot measuring EV-71 replication in the
coinfected culture treated with ACV. EV-71 replication will decrease with
each treatment over the course of three days.
Acknowledgements
Dr. Mathur, for her guidance and patience throughout this project.