by author Development of Dengue and Zika vaccines

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1 Development of Dengue and Zika vaccines JORGE KALIL MD PhD FRCP dr hc Professor and Head of Division Clinical Immunology School of Medicine University of São Paulo Madrid, 2018

2 Developing and testing a live attenuated tetravalent Dengue vaccine

3 GENOME Dengue is a mosquito-borne RNA virus with 4 distinct serotypes: 1,2,3,and 4 3 structural proteins: C, prm, and E E protein is the main target of neutralizing antibody 7 non-structural proteins are associated with the development of cellular immune response Dengue Viruses

4 Dengue Virus: E protein is a major antibody target Simmons et al Advances in the Development of Vaccines for Dengue Fever. Vaccine: Development and Therapy. doi: /vdt.s22577.

5 Dengue Fever Each serotype is capable of causing Dengue disease Fever and Headache Retro-orbital pain Myalgia Arthralgia Hemorrhage Rash Leukopenia Neutropenia Elevated ALT / AST Viremia Serum Antibodies Severe Dengue Fever (2 7 days) and Thrombocytopenia and Petechial rash Bruising Bleeding Coagulopathy and Vascular leakage Pleural effusion Ascites Hemoconcentration DF DF (Unreported) Asymptomatic infections --- Severe dengue Shock Syndrome (DSS): Hypotension Shock

6 Immune response to Dengue infection Infection with one DENV serotype likely provides life-long protection against serotype. Primary dengue infection may predispose to a second severe dengue disease. Virus enhancement non neutralizing antibodies.

7 Antibody-Dependent Enhancement (ADE) Brian R. Murphy and Stephen S. Whitehead Annu. Rev. Immunol :

8 Dengue is both an established and an emerging/re-emerging disease WHO 2,5 billion people at risk Over 300 million annual infections 500,000 hospitalizations Circulation of all 4 serotypes DEN1 DEN2 DEN3 DEN4 DEN1 DEN2 DEN3 DEN4 DEN1 DEN2 DEN3 DEN4 DEN1 DEN2 DEN3 DEN4 DEN1 DEN2 DEN1 DEN2 DEN3 DEN4 DEN1 DEN2 DEN3 DEN4 DEN1 DEN2 DEN3 DEN4 DEN1 DEN2 DEN3 DEN4

9 Percent of Positive Samples for each DENV Serotype distribution varies across the years 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Dengue Serotype Distribution, Brazil, Source: Ministry of Health of Brazil, Health Surveillance Secretariat SVS DENV1 DENV2 DENV3 DENV4

10 Why develop a live attenuated DENV vaccine? Live attenuated vaccines have been successful for other flaviviruses: YF and JE Live attenuated vaccine Induces both humoral and cellular immune responses Are highly immunogenic, requiring only one or two doses Expected to induce lifelong immunity Can be very economical to produce and can be manufactured locally in endemic countries

11 Attenuation NIH/LID - Vaccine Viruses Defined deletion mutations into the 3 UTR and/or chimerization

12 Recombinant Live Attenuated DENV vaccine strategies

13 Pre-clinical studies Attenuation shown in SCID-HuH-7 mice and Rhesus macaques Immunogenicity in Rhesus macaque Vaccine virus do not infect the midgut of mosquitoes Main results obtained in US Phase I trials - Safety Safety Profile Low Viremia Vaccinees did not develop a dengue-like illness Minimal local reactogenicity The most common systemic AR non-pruritic rash Seroconversion rates DENV1 30: 94% DEN2/4Δ30: 100% rden3δ30/31: 95% rden4 30: 95%

14 Dengue Vaccine Butantan Institute Partnership Butantan Institute Lab Infectious Diseases at NIH Transfer of the live attenuated viruses to Butantan Institute Industrial development Virus production yields and purification Virus stabilization and lyophilization Clinical Development

15 University of São Paulo STEP A 50 subjects STEP B 250 subjects Butantan DV Phase II Clinical Trial 300 volunteers, 18 to 59 years:.100 dengue-naïve participants (allocation vaccine placebo 4:1). 200 dengue-exposed participants (allocation vaccine placebo 3:1) 6 mo exploratory endpoint 50 dengue-naïve participants 20 liquid (NIH TV003), 20 lyophilized (Butantan-DV), 10 placebo Sample collection every 3 days Bridging study: Butantan-DV and TV dengue-exposed participants 40 subjects Sample collection every 3 days 160 dengue-exposed and 50 dengue-naïve participants 210 subjects - Vaccination in Step A and B completed on Sep Follow-up period is still ongoing 5 years 5 years 5 years

16 Intensity* DEN-01-IB: Intensity of adverse reactions Safety results up to 21 days after vaccination Participants with reactions Dengue-naïve participants reactions Vaccine (AR=28 4 n=80) Placebo (AR=25 n=20) p-value Dengue-exposed participants reactions Vaccine (AR=446 n=150) Placebo (AR=77 n=50) p-value p-value naïve:exposed 90.0% 35.0% < % 58.0% < Grade % 92.9% > % 84.2% Grade % 7.1% 13.8% 15.8% Grade 3 0% 0% 0.9% 0% Grade 4 0% 0% 0% 0%

17 DEN-01-IB: Systemic adverse reactions Safety results up to 21 days after vaccination Adverse reaction Vaccine (n=80) Dengue-naïve participants Placebo (n=20) p-value Dengue-exposed participants Vaccine (n=150) Placebo (n=50) p-value p-value naïve:exposed Rash 70.0% 10.0% < % 6.0% < Headache 42.5% 15.0% % 38.0% Myalgia 20.0% 0% % 16.0% Arthralgia 5.0% 0% % 2.0% Retro-orbital pain 7.5% 5.0% >0, % 2.0% Fever 5.0% 0% % 8.0% Pruritus* 10.0% 0% % 8.0% *Unsolicited adverse reaction. One case of pruritus (grade I) reappeared on day 29. All the adverse reactions were transient and self-limited No new adverse reactions occurred between day 22 and 182

18 DEN-01-IB: Systemic adverse reactions - Rash Safety results up to 21 days after vaccination Dengue-naïve vaccine recipients Dengue-exposed vaccine recipients Characteristic Median P % Median P % p-value naïve:exposed Start date 10 days days Duration 8 days days Asymptomatic 92.9% 80.0% Examples of rash after vaccination

19 Wild-type Dengue Rash

20 0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100% DEN-01-IB: Step A Dengue-naïve participants Per protocol PRNT results NIH TV003 (n=20) Butantan-DV (n=17) Seroconversion Mean Geometric Seroconversion Mean Geometric p- (95% CI) Peak titer up to day (95% CI) Peak titer up to day value Serotype 91 (95% CI) 91 (95% CI) DENV1 95.0% ( ) 130.7( ) 94.1% ( ) 572.7( ) DENV2 85.0% ( ) 377.5( ) 94.1% ( ) 346.0( ) >0.999 DENV3 85.0% ( ) 96.1( ) 82.4% ( ) 454.7( ) DENV4 85.0% ( ) 408.5( ) 88.2% ( ) 150.7( ) >0.999 Butantan-DV NIH TV003 Tetravalent response 76.5% Tetravalent response 75.0% Trivalent response 17.6% Trivalent response 15.0% Monovalent response 5.0%

21 (% ) C D H L A -D R + C C R 5 + C D 4 T C e lls Butantan-DV: Cellular Immune Response Step A (dengue-naïve participants): CD4+ T cell activation C D H L A -D R + C C R 5 + C D 4 T C e lls L y o ph L íq u id P la c e D 0 -V D 0 -P D 6 -V D 6 -P D 1 2 -V D 1 2 -P D 9 1 -V D 9 1 -P

22 Butantan DV Phase III Clinical trial

23 DEN-03-IB Phase III Clinical Trial - Overview Sample size: 16,944 participants 80% vaccine efficacy Dengue incidence: 0.337% Vaccine/placebo allocation 2:1 Safety database to detect 1:1000 adverse events per age group Three age groups: 18-59, 7-17, 2-6 years old Phase III subjects Single dose 5 years 450 participants in two age groups and 7-17 years old DSMB internal review: 21-days safety analysis to include 2-6 years group 00 5 years Open to all participants and all age groups DSMB internal reviews: 21-days safety data on 1350 and 2700 participants per age group. Then, at least, every six months

24 DEN-03-IB: Dengue surveillance (five years) Built on Family Health Strategy Cooperation of Community Health Agents Based Basic Care Units Follow-up of families Active surveillance (phone, SMS, home visits) Fever (2 days) / clinical suspicion Clinical assessment Warning signs (hospitalized or not) Severe dengue (hospitalized or not) Lab assessment RT-PCR and NS1 ELISA (RT-PCR CHKV/ZIKV) NS1 rapid test

25 DEN-03-IB Phase III Trial Clinical sites selection

26 DEN-03-IB Phase III trial Fever/dengue surveillance Active surveillance Contact each participant every week Basic Care Unit refer febrile cases Investigation of febrile cases All febrile cases have clinical and lab assessment Clinical assessment dengue, zika and chikungunya All cases are followed up until resolution

27 Centro Volunteer Recruitment 3/20/ anos 7-17 anos anos Total C1 - HCFMUSP C2 STACASASP C3 - FAMERP C4 HC-UFMG C5 - UFS C6 CPqAM/Fiocruz C7 - UFC C8 FMT-HVD C9 - UFRR C10 - UnB C11 - CEPEM C12 HUJM C13 - UFMS C14 HSL-PUCRS Total

28 Fever Investigation (1st quarter 2018) Fever/ suspects of dengue (21 days after vaccination) N = 210 episodes Diagnosis Hypothesis Diagnosis Chikungunya* Dengue* Zika* Number of cases (*) Confirmed by PCR

29 I think being mature for this position

30 Pentavalent-Z: Second generation live DENV vaccines DEN1 DEN2 DEN3 DEN4 + ZIKV C prm E NS1 NS2A NS2B NS3 NS4A NS4B NS5 3 Laboratory of Infectious Diseases Δ30 30 C prm E NS1 NS2A NS2B NS3 NS4A NS4B NS5 3 30/31 C prm E NS1 NS2A NS2B NS3 NS4A NS4B NS5 3 Δ30 C prm E NS1 NS2A NS2B NS3 NS4A NS4B NS5 3 Δ30 C prm E NS1 NS2A NS2B NS3 NS4A NS4B NS5 3 Δ30 C prm E NS1 NS2A NS2B NS3 NS4A NS4B NS5 3 rden1δ30 rden2/4δ30 rden3δ30/31 rden4δ30 rzikv/d2δ30 rzikvδ30 30

31 Butantan-DV Group Butantan (São Paulo) Neuza Frazatti-Gallina Alexander Precioso Ricardo Palacios Beatriz Thomé Gabriella Mondini Ana Paula Batista Joane Prado USP (São Paulo) Jorge Kalil Esper Kallas Lucia Arruda Campos Instituto Adolfo Lutz (São Paulo) Maria do Carmo Timenetski Cecília Simões FAMERP (São José de Rio Preto) Maurício Nogueira LID NIAID-NIH (USA) Steve Whitehead JHSPH (USA) Anna Durbin GSID (USA) Don Francis Quintiles Brasil Eduardo Tedeschi Fernanda Pacheco VPPLR-Fiocruz (Rio de Janeiro) Karla Gram Thais Amaral Photo: R Stuckert Filho/PR - 22 Feb 2016 Butantan DV Group SCMSP- CSEBF (São Paulo) José Cássio de Moraes Hilda Salinas UFMG (Belo Horizonte) Mauro Teixeira Helton Santiago UFS (Aracaju/Laranjeiras) Ricardo Gurgel UFC (Fortaleza) Ivo Castelo-Branco Coelho FMT-HVD (Manaus) Marcus Lacerda HSL-PUCRS (Porto Alegre) Fabiano Ramos Cristina Bonorino CPqAM-Fiocruz (Recife) Ernesto Marques Rafael Dhalia Cintia Braga Celina Turchi UFRR (Boa Vista) Allex da Fonseca CEPEM (Porto Velho) Dhelio Pereira UnB (Brasília DF) Gustavo Romero UFMS (Campo Grande) Erivaldo Elias UFMT (Cuiabá) Cor Jesus Fontes

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33 Developing and testing possible ZIKA vaccines

34 Zika virus spread,

35 Symptoms of Zika Virus Infection Severe complications: Congenital Zika syndrome - microcephaly Guillain-Barre syndrome

36 Clinical presentation

37 D E N V Z IK V Innate immune responses Interferon type I (a, b), II (g), III (l) INF-stimulated genes T-cell responses CD4+ CD8+ Immune-mediated control of ZIKV Neutralizing antibody responses Envelope-specific ZIKV-specific Cross reactive C D 4 r e s p o n s e s 3 9 % C 3 2 % p rm 7 % N S 1 1 % N S 2 B 4 % N S 3 9 % N S 4 A 1 % N S 4 B 6 % N S 5 NS3 prm 3 5 % C C C prm 5 % p rm % E % N S % N S 2 A % N S 2 B % N S % N S 4 A % N S 4 B % N S 5 Xu, et al., PLoS Curr 2016 Nov 15, pii. NS5 C D 8 r e s p o n s e s E C prm NS3 2 7 % C 1 5 % p rm 9 % E 1 0 % N S % N S 2 A 3 % N S 2 B 6 % N S 3 2 % N S 4 A 2 % N S 4 B 1 3 % N S 5 4 % C 4 % p rm 7 % E 5 % N S 1 3 % N S 2 A 2 % N S 2 B 2 9 % N S 3 4 % N S 4 A 1 6 % N S 4 B 2 8 % N S 5 Preliminary, D. Weiskopf. LJI

38 Inactivated Subunit / Peptide Live attenuated Vectored DNA / RNA ZIKV Vaccine Approaches ZIKV vaccine approaches WRAIR / NIAID / BARDA / Sanofi, USA PaxVax, CA, USA NewLink Genetics, MA, USA GSK, USA/Belgium Emergent, MD, USA Takeda, Japan Bharat Biotech, India Protein Sciences, CT, USA Bharat Biotech, India Replikins, MA, USA NIAID-LID / Instituto Butantan, USA/Brazil UTMB / Instituto Evandro Chagas, USA/Brazil Sanofi Pasteur, France Jenner Institute (Chimp adenovirus), UK Harvard University (VSV), MA, USA Themis Bioscience (Measles), Austria NIAID-VRC (Biojector needle-free), USA Inovio Pharmaceuticals (Electroporation), PA, USA IDRI (RNA), WA, USA GSK (RNA), USA/Belgium Moderna Therapeutics, MA, USA

39 1. Who to vaccinate? Special populations Pregnant women, immunocompromised Serological background 2. When to vaccinate? Age Doses and durability 3. Safety? Replicating vs. non-replicating vaccines Guillain Barré syndrome Adjuvants 4. Sustainability? Will it still be relevant after development? 5. Will future incidence of disease support efficacy evaluation? 6. Cost? ZIKV Vaccine Questions/Concerns

40 Selected vaccines under development DNA-based vaccines Based on NIH WNV vaccine tested in Phase I trial Whole virus inactivated vaccine Based on licensed JEV vaccine NIAID, WRAIR, BARDA, Sanofi Pasteur Live attenuated vaccine Based on the NIH tetravalent dengue vaccine

41 NIAID Vaccine Research Center DNA Vaccine

42 Production of Zika Virus DNA Vaccines Evaluation in mice Protection in NHPs Phase I clinical evaluation PrM/E of ZIKV-PF/2013

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44 6 rhesus per group Dosing on Week 0 & 4 IM Pharmajet Challenge week 8: ZIKV PR 1000 pfu Neutralizing activity: Flow cytometry with ZIKV RVPs VCR DNA Vaccine VRC mg x 2 VRC mg x 2 VRC mg x 2 VRC mg x 1 Control DNA - 4 mg x 2

45 AS Fauci/NIAID

46 VCR Zika DNA Clinical trials status update Initial Phase 1, VRC 319 (Plasmid 5288) 80/80 enrolled Vaccinated week 0 and 12 Vaccinated week 0, 4, 20 2 nd Phase 1, VRC 320 (Plasmid 5283) - 37/45 enrolled. Data available early May---this will inform Phase 2/2b Phase 2/2b, VRC 705 (Plasmid 5283) Enrollment in Part A Began March 2017 Enrollment in Part B June 2017-Dec 2017 Final dosing under development Likely 4 mg, 0, 4, 8 weeks Interim assessments after 15 and 30 Zika cases

47 A Phase 2b, randomized trial to evaluate the safety and immunogenicity of a Zika Virus DNA Vaccine Healthy Volunteers Ages sites in the US, Caribbean, Central and South America Accelerated planning: Phase 2/2b Zika DNA WT vaccine candidate (plasmid 5283) First subject March 29 Houston Part B proceeds if Phase 1 and Part A results promising Blinded evaluation of case rates to increase sample size as needed Protocol Chairs: Julie Ledgerwood and Grace Chen IND Sponsor: VRC/NIAID

48 Part A Zika Phase 2/2b Selected sites Regulatory submissions Complete or in progress Site Name (PI Name) Puerto Rico Clinical and Translational Research Consortium (PRCTRC) (Diaz) Baylor College of Medicine (Patel) University of Miami Florida Miller School of Medicine Clinical Research Unit (Fischl) San Juan City Hospital Research Unit PR NICHD CRS (Rosario) Fundación de Investigación de Diego (Ortiz-Lasanta) ASCA CRS Iquitos (Morales) Centro de Pesquisas Clínicas do Instituto Central da FMUSP / Univ of Sao Paulo (Kallas, Kalil) Fundacion INCIENSA (FUNIN) (Gonzales) Costa Rican Center of Medical Research (CCIM) (Herrera) Location San Juan, Puerto Rico Houston, TX, USA Miami, FL, USA San Juan, Puerto Rico San Juan, Puerto Rico Iquitos, Peru Hospitales Civiles de Guadalajara "Fray Antonio Alcalde" (Otero) Instituto Conmemorativo Gorgas de Estudios de la Salud site (Sosa); Sao Paulo, Brazil Santa Cruz, Costa Rica Puntarenas, Costa Rica Guadalajara, Mexico Panama City, Panama

49 Walter Reed Army Institute of Research Inactivated Virus Vaccine

50 Innactivated Zika Vaccine (ZPIV) Formalin-inactivated Zika virus PR strain obtained from CDC Manufactured by WRAIR based on technology used for JEV vaccine WRAIR and DMID/NIAID conducting pre-clinical studies (fully protective in mice and NHPs) DMID/NIAID and WRAIR supported Phase I clinical evaluation CRADA between WRAIR and Sanofi Pasteur to transfer technology to develop ZPIV Sanofi Pasteur planning for late stage development

51 WRAIR Purified Inactivated Vaccine 8 rhesus per group Dosing on Week 0 & 4 SC 5 ug + Alum Neutralizing activity: Microneut assay

52 PIV vaccinated Placebo control Log ZIKV Copies/ml Log ZIKV Copies/ml Challenge week 8: ZIKV PR 1000 pfu ZIKV BR 1000 pfu WRAIR Purified Inactivated Vaccine Plasma Urine CSF sham 8/ grou route or ZIK

53 In Progress: 1) WRAIR Flavivirus naïve YF vaccinated JE vaccinated 2) VTEU (SLU) Flavivirus naïve Dose de-escalation ZPIV Phase I Clinical Trials Vaccine formulation ZPIV 5 ug inactivated virus + Alhydrogel Generally 2 doses at 0 and 4 weeks Red = enrollment complete 3) BIDMC (WRAIR funded) Flavivirus naïve Schedule optimization: 0/2, 0/12 4) VTEU (Puerto Rico) Flavivirus background immunity Dose de-escalation

54 NIAID - Laboratory of Infectious Diseases Live Attenuated Chimeric Virus Vaccine

55 Phase III underway Live Attenuated Vaccine for DENV / ZIKV Pentavalent DENV + ZIKV DEN1 DEN2 DEN3 DEN4 + ZIKV Δ30 C prm E NS1 NS2A NS2B NS3 NS4A NS4B NS C prm E NS1 NS2A NS2B NS3 NS4A NS4B NS5 3 30/31 C prm E NS1 NS2A NS2B NS3 NS4A NS4B NS5 3 Δ30 C prm E NS1 NS2A NS2B NS3 NS4A NS4B NS5 3 Δ30 C prm E NS1 NS2A NS2B NS3 NS4A NS4B NS5 3 rden1δ30 rden2/4δ30 rden3δ30/31 rden4δ30 rzikv/d2δ30 In endemic areas, vaccine is needed for both DENV and ZIKV ZIKV component may also be suitable as stand-alone vaccine Pre-clinical development

56 CMV CMV cdna Constructs for Chimeric Viruses 5 NCR 5 NCR ZIKV C prm E NS1 NS2A NS2B NS3 NS4A NS4B NS5 Ampicillin R ZIKV Ampicillin R Intron ZV-D2 (14,214 nt) pacnr backbone Intron ZV-D4 (14,282 nt) pacnr backbone DENV-2 DENV-4 p15a origin of replication Intron C prm E NS1 NS2A NS2B NS3 NS4A NS4B NS5 ZIKV: Brazil/Paraiba/2015 DENV-2: Tonga/74 DENV-4: Dominica/81 p15a origin of replication 3 NCR Δ30 3 NCR Δ30 RBZ RBZ TERM TERM

57 CMV CMV cdna Constructs for Chimeric Viruses 5 NCR 5 NCR ZIKV C prm E NS1 NS2A NS2B NS3 NS4A NS4B NS5 Ampicillin R ZIKV Ampicillin R Intron ZV-D2 (14,214 nt) pacnr backbone Intron ZV-D4 (14,282 nt) pacnr backbone DENV-2 DENV-4 p15a origin of replication Intron C prm E NS1 NS2A NS2B NS3 NS4A NS4B NS5 ZIKV: Brazil/Paraiba/2015 DENV-2: Tonga/74 DENV-4: Dominica/81 p15a origin of replication 3 NCR Δ30 3 NCR Δ30 RBZ RBZ Significant contribution to CD4+ and CD8+ responses TERM TERM

58 N = 4 monkeys/group 1 dose, SC, 4 log 10 PFU Studies in Rhesus monkeys rzikv/d2δ30 rzikv/d4δ30 ZIKV-Nicaragua/2016 ZIKV-SJRP/2016 wt ZIKV-Paraiba/2015 Vaccine strains Sampling Day 0, 2, 4, 6, 8: Serum, saliva, urine for viremia Day 28, 42: Serum for PRNT immunogenicity Human challenge strains Laboratory wt strain Day 56 - wt ZIKV-Paraiba/2015 challenge to evaluate protection Compare to wt ZIKV to determine level of attenuation

59 Mean titer (log 10 PFU/mL) Mean titer (log 10 GE/mL) LOD = 0.7 (1 plaque/200 ul) Infectious titer in Vero cells Day Viremia in monkeys LOD = 2.9 C T <38 RT-PCR genome titer Day ZIKV-Nicaragua/2016 ZIKV-Paraiba/2015 ZIKV-SJRP/2016 rzikv/d4 30 rzikv/d2 30

60 Mean titer (log 10 PFU/mL) Mean titer (log 10 GE/mL) LOD = 0.7 (1 plaque/200 ul) Infectious titer in Vero cells Day Virus in monkey urine LOD = 2.9 C T <38 RT-PCR genome titer Day ZIKV-Nicaragua/2016 ZIKV-Paraiba/2015 ZIKV-SJRP/2016 rzikv/d4 30 rzikv/d2 30

61 Neutralizing antibody titers in monkeys Virus N Mean PRNT 50 Mean EC 50 RVP Flow Assay Day 0 Day 28 Day 42 Day 0 Day 28 Day 42 Nicaragua/ < < 60 15,656 9,149 SJRP/ < < 60 13,690 6,010 Paraiba/ < < 60 14,491 9,809 rzikv/d < < rzikv/d < 10 < 10 <10 < Placebo 4 < 10 < 10 <10 < 60 < 60 < 60

62 Neutralizing antibody titers in monkeys Virus N Mean PRNT 50 Mean EC 50 RVP Flow Assay Day 0 Day 28 Day 42 Day 0 Day 28 Day 42 Nicaragua/ < < 60 15,656 9,149 SJRP/ < < 60 13,690 6,010 Paraiba/ < < 60 14,491 9,809 rzikv/d < < rzikv/d < 10 < 10 <10 < Placebo 4 < 10 < 10 <10 < 60 < 60 < 60 Will these titers be protective?

63 Mean titer (log 10 PFU/mL) ZIKV challenge of monkeys Day log 10 PFU of ZIKV-Paraiba/2015 to evaluate protection Infectious titer in Vero cells N=2 N= Day Primary inoculation Placebo ZIKV-Nicaragua/2016 ZIKV-Paraiba/2015 ZIKV-SJRP/2016 rzikv/d2 30 rzikv/d4 30 LOD = 0.7 (1 plaque/200 ul)

64 Thanks