Journal Club Stuart Mather – 21st October 2013

About the author – Ed Wright

• BSc Virology (1999 – Edinburgh); PhD in Molecular Virology (2003 – Cambridge)• MRC/UVRI Uganda Research Unit on AIDS (2004-2005)• UCL – Postdoctoral Research Fellow in Robin Weiss lab – (2005-2011)• University of Westminster – Senior Lecturer & Principal Investigator at VPU

Fitzrovia labs – (2011-present)

Rabies• Viral infection of the brain and central nervous system – zoonotic (cross species;

from animals to humans)• Transmitted in saliva – e.g. the bite of an infected dog

• Symptoms – paraesthesia, malaise, fever, headache leading to acute pain, hyperactivity, excited/enraged behaviour, hydrophobia, paralysis and death

• Symptomatic cases are nearly always fatal• Post-exposure prophylaxis (PEP) during virus incubation period can prevent illness –

≈15 million receive PEP annually

http://dog-bitetreatment.com/category/rabies-in-dog-and-treatment http://asylumeclectica.com/asylum/malady/archives/rabies.htm

Global burden of rabies

• ≈55,000 deaths per year – 95% in Africa and Asia• Over 3 billion people worldwide at a realistic risk of transmitting rabies

Rabies virus biology

• Member of the Lyssavirus genus and Rhabdoviridae family

• Enveloped, bullet-shaped virus• ≈ 120nm long and 75nm wide• Negative sense, single-stranded,

linear RNA genome of ≈11kb, encoding for 5 proteins

• Glycoprotein (G) = responsible for virus binding to cellular receptors (e.g. nAChR – acetylcholine receptor) and membrane fusion

• G is also the main virus antigen

http://www.nhs.uk/Conditions/rabies/Pages/introduction.aspx

http://viralzone.expasy.org/all_by_species/22.html

Lyssavirus genus

Banyard AC et al Adv Virus Res. 2011;79:239-89. doi: 10.1016/B978-0-12-387040-7.00012-3.

Traditional rabies serology

• Fluorescent Antibody Virus Neutralisation (FAVN) Test• Rapid Fluorescent Focus Inhibition Test (RFFIT)

• Enzyme Linked Immunosorbent Assay (ELISA)

http://www.vet.k-state.edu/depts/dmp/service/rabies/favn.htm

Infection

Neutralisation

http://www.cdc.gov/rabies/specific_groups/doctors/serology.html

Pseudotype viruses

• ‘Chimeric’ viruses made up of a retroviral core (e.g. HIV), a heterologous envelope (e.g. rabies G) and encapsulating a quantifiable reporter gene (e.g. luciferase)

• HIV - core• Rabies G – envelope• Luciferase – reporter

• Non-infectious - Can be used instead of infectious virus in serological assays to determine neutralising antibody titres

Pseudotype virus production

Mather et al (2013) Future Virology 8(8); 745-755

4 main aims of the study:

• Comparative serology using RABV pseudotype neutralisation assay against FAVN in a vaccination trial

• Production of Mokola (MOKV), Duvenhage (DUVV) and Lagos bat (LBV) pseudotype viruses

• Incorporation of lacZ as a pseudotype reporter gene

• Stability of pseudotype viruses

Outline of rabies vaccination trial

Pseudotype neutralisation assay (PNA) performance

FAVN assay performance

Correlation between PNA and FAVN

Production of other lyssavirus pseudotypes

Incorporation of lacZ reporter gene

Stability of pseudotype viruses

Summary

• Rabies pseudotype neutralisation assays perform as well as FAVN for vaccine evaluation

• MOKV, LBV and DUVV lyssavirus pseudotypes have been successfully produced

• lacZ is a cheaper alternative to luciferase and GFP reporter genes

• Rabies (CVS-11) pseudotypes are relatively stable after freeze-thawing and long term storage