Advances in Marek s Disease Vaccine Development: Michel Bublot, DVM, PhD - Merial R&D Asian Avian Forum 2016, Tokyo, July 12-13
Marek s Disease Control Good flock management Cleaning, disinfection Adequate downtime between flocks Biosecurity Vaccination 2
Marek s disease history MDV1 1907 1922 1950-60s 1968 1970s 1980s 1990s 2000s mmdv vmdv vvmdv vv+mdv Serotype 3: HVT Serotype 2: SB1 Serotype 1: CVI988 (EU) CVI988 (USA) adapted from Gimeno I.M., 2008, Vaccine, 26S, C31-C41
Marek s disease vaccines Serotype Virus Reference strain(s) Year 3 HVT FC126 1970s 2 MDV2 SB-1; 301b 1980s 1 MDV1 CVI988 (Rispens) 1970s CVI988 still the best vaccine since the early 1970s
Marek s vaccines combinations Serotype Virus Efficacy Broilers Colored birds Pullets Breeders 3 HVT + 2+3 SB-1+HVT ++ 1 CVI988 +++ 1+3 CVI988+HVT +++(+) 1+2+3 CVI988+SB-1+HVT +++(+) Increased protection
Revaccination (D1 & D7) V1 (D1) V2 (D7-8) Challenge - Day Protection Index HVT+SB1-648A (vv+) D14 23% HVT+SB1 HVT+SB1 648A (vv+) D14 24% CVI988-686 (vv+) D9 88% CVI988 CVI988 686 (vv+) D9 91% No effect if 2 nd administration given 7 days later Gimeno et al. (2012) Av. Path. 41:59-68 ;Gimeno et al. (2012) Av. Dis. 56:295-305
Revaccination (in ovo & SC) V1 (in ovo) V2 (D1) Challenge Protection Index HVT - 648A (vv+) D14 46% HVT HVT+SB1 648A (vv+) D14 70%* - HVT+SB1 648A (vv+) D14 50% HVT+SB1-648A (vv+) D2 0% HVT HVT+SB1 648A (vv+) D2 25%* - HVT+SB1 648A (vv+) D2 0% Better protection if in ovo + SC & the 2 nd vaccine is stronger Gimeno et al. (2012) Av. Path. 41:59-68 ;Gimeno et al. (2012) Av. Dis. 56:295-305
Marek s vaccines are unique! 1 st anti-tumor vaccine 1 st in ovo vaccine Early onset of protection Life-long protection Cell-associated virus Liquid nitrogen storage Low maternally-derived Ab interference However, no sterilizing immunity MDV infection, shedding & transmission
MDV Virulence Evolution No vv++ so far Jarosinski et al. (2006) Exp. Rev. Vacc. 5:761-72 (adapted from Witter (1998) Avian Path. 27:S46-53)
Vaccination failures (1) Vaccine transport & storage Vaccine preparation Water bath (27 C), timing Full dose early onset Tested antibiotics
Vaccination failures (2) Vaccine administration 1 bird missed = 1 unprotected sterile blue dye In ovo: Right time & place (SC or amniotic cavity) Chick quality: Avoid immunosuppression! CIAV, IBDV, reovirus, Mycotoxins Stress Biosecurity!
Vaccination failures Real examples Will Landman (GD Deventer) Insufficient dose (low titer) due to bad management of liquid nitrogen solved using an electronic device Early exposure: high MDV load in the dust of the farm solved by increasing cleaning and desinfection Bacterial contamination in hatchery: Enterococcus faecalis (joint disease) solved by filters on the decompression needles and mending leaky bags 12
How do MD vaccines protect? Innate immunity Early response IFN, Macrophage (NO), NK cells, Adaptive immunity Cellular immunity: genetic resistance (MHC) CD8 Cytotoxic T cells CD4 Helper T cells Humoral immunity: Less important (cell-associated virus) MDA neutralizing Ab (gb) protection against early immunosupp. Haq et al. (2013) Dev. Compar. Immunol. 41:439-46
Use of real time PCR Follow up of vaccination (Baigent et al., 2006; Gimeno et al., 2008) Vaccine (HVT, SB1, CVI988) specific PCR 6 pinfeathers taken at 17-21 days Highly variable load Chicken breed & Vaccine dependent Estimate of the % vaccine take not efficacy! Follow up of challenge (Gimeno et al., 2008) MDV1 load in blood Marek s disease lesion Diagnostic MD lesion No MD lesion 3 wks 5 wks 15 wks
MD protection with HVT vs HVT vector vaccines MD protection at the same dose (1500 PFU): HVT A, B: differences in protection rhvt A, B, C, D : usually lower than HVT and differences in protection (rhvt-a > rhvt-b) MD protection at the commercial dose: rhvt-b at 4000 PFU > rhvt-b at 1500 PFU I. Gimeno, 2016 Full dose should be used!
Compatibility CVI988 with HVT vector vaccines CVI988 Rispens - Compatibility with HVT-IBD Vaccine 1 Vaccine 2 MD protection IBD protection HVT-IBD Rispens A 96.6% 100% HVT-IBD Rispens B 100% 100% HVT-IBD Rispens C 96.6% 100% HVT-IBD Rispens D 100% 100% HVT-IBD - n.d. 100% - - 6.7% 0% Lack of interference between Rispens and HVT-IBD Lemiere S. et al., 2011, Avian Dis., 55, 113-118
A need for new Marek s disease vaccines 17
New generation of MD vaccines Goal: SPF Safety MDA+ Efficacy New vv+ attenuated strains Safety in SPF: 100 passages Efficacy in MDA+: 60 passages Genetic basis of attenuation still unknown p100 p60 Witter (2002) Avian Dis 46:925-37 Spatz et al. (2012) Virus Gene 45:526-36 Immunomodulators (LPS, CpG, IFN, polyi:c) stimulation of innate immunity Haq et al. (2013) Dev. Compar. Immunol. 41:439-46
New generation of MD vaccines Vector vaccine Fowlpox vector expressing MDV gb and/or cytokine improved HVT vaccines Nazerian et al. (1996) Avian Dis 40:368-76 HVT expressing MDV genes and/or cytokines HVT/MDV chimera Genetically MDV1 attenuated strains BAC & overlapping cosmid, CRISP-R technology Deletion Meq deleted Insertion RM1/CVRM Haq et al. (2013) Dev. Compar. Immunol. 41:439-46
Meq-deleted Md5 (rmd5 Meq) =Md5 (vvmdv) with deleted Meq (MDV1 oncogen) p19 p40 Bird p19 p40 Tumors SPF No No Bursal /Thymus atrophy SPF Yes No Efficacy vv+ MDA+ CVI988 <CVI988 %MD in MDA+ Lee et al., 2013 Avian Dis. 57:491-7 CVI988 A B p40 p19
RM1 virus Retrovirus genome: Co-infection of cells/chickens by MDV & retrovirus retrovirus insertion into MDV genome Retrovirus LTR scar inserted in hot spots ( ) MDV genome: RM1: co-infection of vmdv JM/102W & REV No tumors, but severe persistent thymus atrophy Excellent protection in birds with MDA Vaccine % Protection (Md5, vv) CVI988 78% RM1 100% attjm (p48) 34% RM1 Jones et al., 1993 & 1996; Witter et al., 1997
CVRM hybrid vaccine CV = CVI988 TRL UL IRL IRS US TRS RM = RM1 Safety: No thymus atrophy CVI988 LTR RM1 LTR Efficacy: Laboratory: 15x7 line (MDA+) Vaccine % Protection CVRM 85% IP challenge CVI988 63% 648A (vv+) D5 Field (Hy-line): Leghorn W-36 (MDA+) Vaccine % Protection CVRM 85% Shedder challenge 686 (vv+) 18hrs CVI988 A 86% CVI988 B 55% CVI988 C 77% HVT+SB1 56% Lupiani et al. (2013) Avian Dis. 57, 427-31
New MD vaccine research at Merial Many candidates tested ADOL CVRM selected for development Batch not homogenous relative to LTR insertion Plaque purif. and selection of plaques («A», «B» & «C») with 2 LTR Efficacy testing: Commercial broilers vv+mdv T King Shedder challenge «A» plaque selected as new SR-1 vaccine 80% 90 80 70 60 50 40 30 20 10 0 Protection index CVI988 A B C 23 11 th Marek Symposium, July 9 2016, Tours, France
(g) % birds infected Merial new generation SR-1 vaccine - SAFETY Non-oncogenic, safe, no infection of contact in SPF chickens 120 Day Safety Study - Mean body weight 120 Day Safety Study - % bird MD+ 1800 100 80 1700 60 1600 40 20 1500 SR-1 Contact (sham vaccinate) Treatment Sham Vaccinate No statistically significant difference was detected in the body weights of any of the groups 0 Sham Vaccinate/ challenge SR-1 Treatment Contact (sham vaccinate) Sham Vaccinate
Merial new generation SR-1 vaccine - SAFETY No changes in lymphoid organs Bursa Thymus Spleen Bursa Thymus Spleen No Reversion to virulence Bursa Thymus Spleen
Merial new generation SR-1 vaccine - EFFICACY Summary of multiple studies Efficacy studies Required protection
Merial new generation SR-1 vaccine - EFFICACY Compatibility with VAXXITEK SPF birds SC vaccination RB1B challenge 4 days post-vaccination Vaccine MD protection Control 0% New SR-1+ HVT-IBD 100% CVI988 + HVT-IBD 73%
New generation SR-1 vaccine - Summary Genetic stability LTR Insertions stable after at least 5 in vitro and 5 in vivo passages Horizontal transmission from vaccinated to unvaccinated contact chickens was not detected in the tested conditions No changes in lymphoid organs thymus, bursa, or spleen Efficacy!!!
Conclusion Constantly evolving disease Vaccines are the main tool for control Need of constant research New Merial SR-1 vaccine looks promising
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Acknowledgements ADOL Thank you for your attention 有難う / 有り難う Sanjay Reddy, Aly Fadly SEPRL Stephen Spatz Merial R&D Nikki Prichard, Mariana Sa e Silva, Anne Hurley-Bacon, Troy Hughes Teshome Mebatsion, Perry Linz http://g1.globo.com