Efficacy of Topical Drug Therapy for Monkey B Virus Exposure

1. Efficacy of Topical Drug Therapy for Monkey B Virus Exposure R Eberle Center for Veterinary Health Sciences Oklahoma State University Stillwater, OK

2. Monkey B Virus • Macacine herpesvirus 1 • Naturally occurring in genus Macaca • Symptoms similar to HSV in humans • Serious disease is rare in natural host

3. Monkey B Virus: Zoonotic Infections • First isolation from human case in 1932 • About 50 documentedhuman cases total • Infection usually acquired from macaques via bites or scratches • ~80% fatal if untreated, ~20% with immediate drug therapy • Was a “Select Agent” – govt controlled research (now removed from list)

4. Current Treatment for Zoonotic BV Infections • All drugs were developed to treat HSV, not BV • Immediate post-exposure prophylactic treatment is oral ACV or oral ValACV • If any clinical symptoms are evident treatment is i.v. ACV or i.v. GCV • If CNS signs evident treatment is i.v. GCV • There is no scientific evidence that these represent optimal treatment regimens

5. Comparative Drug Efficacy – In vitro Drug EC50 ACV 23.3 ± 4.3 AraA (Tox)5.7 ± 1.6 BUdR >200 BVDU >200 CDV 12.4 ± 2.1 EDU 14.2 ± 5.8 HBPG >200 GCV 18.4 ± 3.6 IUdR (Tox)1.3 ± 0.5 PCV 11.3 ± 1.4 PFA >100 TFT (Tox) 1.3 ± 0.2

6. BV Mouse Model • 10-12 gm female Balb/c • Shave flank • Scarify skin • Apply 105 PFU BV (~10 LD50) • Observe 2x/day, 14-21 days • Drugs given over 7 day course Systemic = inject i,p. Topical = transdermal PLO gel

7. BV Mouse Model: Neurological Scoring & Clinical Signs of Infection Score Clinical Neurological Signs • Abnormal tail-lift reflex (curling of ipsilateral foot/leg) • Paresis of ipsilateral hind leg, still alert & active • Paralysis of ipsilateral hind leg, still alert & active • Bilateral hind limb paralysis, scruffy coat, not very active • Immobile, tremors, dead or requiring euthanasia Normal Abnormal

8. Systemic Efficacy ACV, PCV & EDU Start drugs day -1 for 7 days; i.p. injection 2x/day

9. Systemic Efficacy GCV & CDV Start drugs day -1, i.p. injection 2x/day 100 90 80 70 60 50 40 30 20 10 0 100 90 80 70 60 50 40 30 20 10 0 CDV (mg/kg/day) 100, 50, 25, 12.5,6.2,3.1, 1.6 Percent Survival GCV (mg/kg/day) 200, 100,50,25 0 7 14 0 7 14 Days Post-Infection

10. Neurological Symptoms GCV & CDV Start drugs day -1 for 7 days; i.p. injection 2x/day

11. Effect of Delaying Start of Drug Therapy Virus in DRG 100 80 60 40 20 0 Virus in Spinal Cord CDV (25 mg/kg/day) GCV (100 mg/kg/day) Percent Survival -1 0 1 2 3 4 5 Start of Drug Regimen (DPI)

12. Conclusions • ACV, EDU & PCV not effective • GCV & CDV effective • Only when treatment started before virus gets into CNS • CDV more effective than GCV • CDV effective dose ~10 fold lower than GCV • High CDV doses can prevents development of clinical neurological signs

13. Implications • To be effective treatment must start before virus invades CNS • Best to prevent virus from reaching CNS • Most effective drugs are also toxic • Cannot use drugs most effective against BV • GCV & CDV are also toxic, so treatments are in-patient • Use of less effective drugs may be bad • Ineffective inhibition mayallow virus to replicate & invade nervous system • Infection becomes harder to treat effectively once neurological symptoms become evident

14. Possible Alternative Approach: Topical Drug Treatment? • Some toxic drugs can be used topically • Patients can self-medicate • Lower cost (out-patient) • Easy to administer, likely high patient compliance • Can initiate treatment soon after exposure • Early peripheral treatment may stop virus from accessing the nervous system

15. Trial Topical Drug Treatment 0 1 2 3 0 1 2 3 Neurological Score 5% GCV 5% CDV Days PI Days PI 0 7 14 21 0 7 14 21 Treatment started at: 3 hr PI 6 hr PI 24 hr PI

16. Screening of Drugs for Topical Efficacy 100 80 60 40 20 0 All drugs at 3% Start treatment at 4 hr PI 3x/day for 7 days % Survival Veh ACV PCVGCVCDVTFTRRIIUdR EDU Abrv

17. Comparative Drug Efficacy: Survival 100 80 60 40 20 0 5% 3% 1% 0.3% 0.1% Vehicle Start drug treatments at 24 hr PI 3x/day for 7 days RRI 0 7 14 Days Post-Infection 100 80 60 40 20 0 100 80 60 40 20 0 CDV GCV 0 7 14 Days Post-Infection 0 7 14 Days Post-Infection

18. Comparative Drug Efficacy: Neurological Signs 0 1 2 3 4 5 5% 3% 1% 0.3% 0.1% Vehicle Start drug treatments at 24 hr PI 3x/day for 7 days RRI 0 7 14 Days Post-Infection 0 1 2 3 4 5 0 1 2 3 4 5 CDV GCV 0 7 14 Days Post-Infection 0 7 14 Days Post-Infection

19. Future Experiments • Dual drug regimens: GCV + RRI CDV + RRI • Dual drug efficacy once BV is in CNS • Temporal efficacy of CDV suppression of BV replication in the skin

20. Acknowledgements Collaborators/Personnel: Dr Lara Maxwell Dr George Wright Darla Black Vet Pharmacol CEO GLSynthesis Lab Manager Funding: Dolphin Fdn, ACLAM Fdn

21. Questions?