Introduction. In the past 15 years, several technological advancements have open new perspectives and applications in the field of vaccinology.

Size: px

Start display at page:

Download "Introduction. In the past 15 years, several technological advancements have open new perspectives and applications in the field of vaccinology."

Juliana Stone
5 years ago
Views:

1 Introduction In the past 15 years, several technological advancements have open new perspectives and applications in the field of vaccinology. - Genomics: fasten antigen discovery for complex pathogens (bacteria, parasites). - Genetic engineering: suitable methodologies for recombinant protein expression and recombinant viral vectors or DNA based vaccines. - Chemical synthesis of genes. - A more detailed knowledge on the mecanisms of immune responses and mucosal immunity. - Automatization of immunological assays (ELISAs etc ) 1

2 New technological vaccines in cattle (1) - New vaccine development has been and is hampered by the cost of these large animals and their maintenance in experimental facilities. - In many instances small animal laboratory models are not suitable to study pathogens of ruminants and extrapolation of results have always been hazardous. - Conventional vaccines exist for many diseases and are more economical than newly developped (registering and marketing a vaccine is extremely expensive). 2

3 New technological vaccines in cattle (2) - Funds (at least public) to develop technological vaccines are given priority: - To diseases for which there is no conventional vaccine or conventional vaccines are not very effective - To diseases of compulsory declaration (OIE list) and potentially zoonotic (one health concept). - Also, priority is given for the so called emergency vaccines. 3

4 Contagious Bovine pleuropneumonia From Dupuy V et al, PLOS ONE 2012;7(10):e46821 Mycoplasma mycoides mycoides (Mmm) causes a severe respiratory disease, conventional live attenuated vaccines work partially and need to be applied every 6 to 12 months. Mortality and morbidity are elevated. 4

5 CBPP vaccine design 5

6 Search for relevant CBPP antigens - This experimental vaccine is based on the genomic analysis of Mmm. The genome of Mmm is composed of 975 genes. Antigens of interest should be surface exposed and/or be involved in adhesion (virulence factors). - Genes of interest (coding for putative antigens) were screened with bioinformatic tools: 66 genes were selected. - All 66 genes were chemically synthetized, cloned in plasmids and expressed in E.coli. Gene products (recombinant proteins) were purified and tested by multiplex assays with 35 antisera from animals having recovered from CBPP. All 66 gene products reacted at different levels with antisera. Moreover, they were able to induce antibodies once injected in cattle. 6

7 CBPP vaccine trials The trial was performed in 170 Boran cattle aged 2-3 years. All 66 antigens were tested in 3 consecutive trials in 17 groups. Pools of 5 recombinant proteins (50 µg each) were adjuvanted (CpG-ODN 2007 and 30% Emulsigen) and injected in the neck of their respective animal group. After challenge,2 pools (10 antigens) confered around 80% protection in terms of pathological scores and reduced the Mmm loads Although encouraging, a vaccine based on recombinant proteins will not afford a sufficient protection and a long lasting immunity to eradicate the disease or to use it as an emergency vaccine. 7

8 New prospectives for a CBPP vaccine Vaccination with the purified CPS provides 57% protection similar to a live attenuated vaccine. A combination of recombinant proteins and CPS might increase levels of protection. Vectorization of antigens via recombinant virus might provide better protection 8

9 Tuberculosis the case of a vectorized experimental vaccine Bovine tuberculosis due to Mycobacterium bovis is a worldwide problem with consequences on public health its eradication is underway in several European countries, but the use of efficient vaccines are under study for heavely endemic areas and animal reservoirs. Under the concept of One Health vaccines developped for humans should also be used for animals and vis versa. There is expectation that the use of some types of adenovirus as vectors for desired antigens can be applicable to humans. Indeed, several trials on human volunteers have already been performed. Also, M. Bovis is very similar to M. Caprae provoking in their respective species similar pathologies. Therefore the caprine model can be an alternative to bovine for developping vaccines against tuberculosis. The recombinant adenovirus vaccine tested at IRTA-CReSA was first conceived for humans with antigens from M. Tuberculosis. 9

Tuberculosis the case of a vectorized experimental vaccine The existing vaccine, BCG, is not readily effective in ruminants; it can reduce the prevalence of the disease but cannot be used for

10 Tuberculosis the case of a vectorized experimental vaccine The existing vaccine, BCG, is not readily effective in ruminants; it can reduce the prevalence of the disease but cannot be used for eradication purposes. Immunization with a recombinant adenovirus by itself does not improve levels of protection obtained with BCG. Better resulst in cattle are obtained when combining both vaccines (Vordermeier HM, et al Infect. Immun. 77: ).. 10

11 Results obtained in goats Goats are first administered with BCG and then with recombinant adenovirus by intra muscular injection in the neck. Several weeks latter challenge is performed with M. Caprae. Multidetector computed tomography analysis of gross lung lesions. 11

12 Adenovirus can deliver multi antigens from M. Tuberculosis and protect goats against M. caprae 12

13 Results of the challenge Results are encouraging but still below standards to insure eradication of tuberculosis in ruminants 13

14 Other vectored vaccines for respiratory diseases Beta coronavirus are fast evolving viruses which have shown adaptation to multiple species. In the past few years, new zoonotic coronavirus have emerged (SARS-CoV and MERS-CoV) creating alarm. The question nowadays is which domestic specie will generate the next coronavirus outbreak? 14

15 Source of MERS-CoV: how MERS-CoV infection may be transmitted from primary or secondary animal hosts to humans? Experimental evidence of MERS-CoV susceptibility Susceptibility to MERS-CoV established by experimental infection xperimental and field evidence of MERS-CoV susceptibility Reusken CBEM et al, Emerg Infect Dis Adney DR et al, Emerg Infect Dis. 2016

16 In this scenario, a vast multi species survey of coronavirus is necesary and preparedness with emergency vaccines is recommended by both OIE and WHO. The Modified Vaccinia Ankara (MVA) virus, is a highly attenuated strain of vaccinia virus that was developed towards the end of the campaign for the eradication of smallpox. MVA is widely considered as the vaccinia virus strain of choice for clinical investigation because of its high safety profile. It does not replicate efficiently in primates cells. MVA is a vector for foreign genes in particular those coding for antigens. Furthermore, recombinant virus can be delivered intra nasally inducing mucosal immunity. 16

17 Genome arrangement of MERS-CoV. diagnostic PCR tests *: furin cleavage sites RBD: receptor binding domain Jasper F. W. Chan et al. Clin. Microbiol. Rev. 2015;28:

A vaccine against MERS-CoV tested in dromedary camels

2016; 351:77-81 Goup 2 Immunizations (4 weeks appart)

MVA-S MVA-wt MVA-wt PBS PBS 2x10 8 PFU MVA-S i.n.

18 A vaccine against MERS-CoV tested in dromedary camels Experimental design Haagmans BL et al, Science. 2016; 351:77-81 Goup 2 Immunizations (4 weeks appart) Challenge (3 weeks after boost) MVA-S MVA-S MVA-S MVA-S MVA-wt MVA-wt PBS PBS 2x10 8 PFU MVA-S i.n. and 10 8 PFU i.m. Control vaccinated Control 10 7 TCID 50 MERS-CoV i.n.

19 Serum virus neutralizing responses MERS-CoV ü All MVA-S vaccinated animals develop neutralizing MERS-CoV speciyic antibody titers. Non-vaccin. vaccinated MVA ü Detection of neutralizing MVAantibodies. week 0 week 4 week 7 After immunization Non-vaccin. vaccinated Camelpox virus ü Antibodies cross neutralize the orthopoxvirus camelpox virus. Non-vaccin. vaccinated

20 Histopathology and expression of viral antigen and viral RNA in nasal respiratory epithelium MVA-S vaccinated In situ hybridization Control 4dpi ü Necrosis of epithelial cells, inyiltration of neutrophils, lymphocytes. Control ü No lesions ü Few viral positive cells ü Few viral RNA MVA-S vaccinated ü Detection of less MERSCoV viral RNA in the nose of vaccinated animals. Abundant viral antigen and viral RNA

21 Conclusions of the MVA-S vaccination in Dromedary camels v Vaccination of DC with MVA-S induce protective immunity resulting in reduction of infectious MERS-CoV excreted. v Induction of serum neutralizing antibodies, that crossneutralize camelpox virus à DUAL USE of the candidate vaccine in dromedaries.

Viruses: Select Agents and Emerging Pathogens. Patricia Bolívar MS., CLS, PHM

Viruses: Select Agents and Emerging Pathogens Patricia Bolívar MS., CLS, PHM Objectives Review Select Agent Viruses. Key features to recognize Smallpox virus Update on emerging Viruses of possible pandemic