alexa Immunoinformatic Approach for Epitope-Based Peptide Vaccine against Lagos Rabies Virus Glycoprotein G

ISSN: 1745-7580

Immunome Research

  • Research Article   
  • Immunome Res 2016, Vol 13(3): 137
  • DOI: 10.4172/1745-7580.1000137

Immunoinformatic Approach for Epitope-Based Peptide Vaccine against Lagos Rabies Virus Glycoprotein G

Omar Hashim Ahmed1*, Arwa Abdelhalim2, Sahar Obi3, Khoubieb Ali Abd_elrahman4, Ahmed Hamdi5 and Mohammed A.Hassan5
1Department of Pharmacology, Faculty of Pharmacy, International University of Africa, Khartoum, Sudan
2Sudan Medical Council, Sudan
3National Ribat University, Sudan
4University of Medical Science and Technology, Sudan
5Africa City of Technology, Sudan
*Corresponding Author: Omar Hashim Ahmed, Department of Pharmacology, Faculty of Pharmacy, International University of Africa, Khartoum, Sudan, Tel: 00249916250199, Email: [email protected]

Received Date: Jun 11, 2016 / Accepted Date: Jun 28, 2017 / Published Date: Jul 07, 2017

Abstract

Background: Lagos rabies virus belongs to lyssavirus genus responsible for meningoencephalomyelitis in mammals that affect millions of people around the world and causes thousands of human deaths every year, to the best of our knowledge there is no peptide vaccine designed for Lagos rabies virus. The resulting peptide vaccine is expected to be more immunogenic and less allergic than conventional biochemical vaccines. The aim of this study was to design an Insilco peptide vaccine for Lagos rabies virus using Immunoinformatic tools.
Methods and Materials: Sequences of glycoprotein G of Lagos rabies virus was retrieved from NCBI, the retrieved sequences were then treated using different Immunoinformatic tools for B cell to find out the most conserved, surface and antigenic epitopes, and for T cell to find conserved peptides and to test their binding affinity to different MHC1 and MHC11 alleles. Then population coverage analysis and homology modeling was performed for most promising epitopes to show their structural positions in glycoprotein G.
Results and Conclusions: B cell tests were conducted for Bepipred with 22 conserved epitopes, Emini surface accessibility prediction with 12 conserved surface epitopes and Kolaskar and Tongaonkar antigenicity test with only three conserved epitopes being antigenic. 23 conserved epitopes were interacted with different MHC-1 alleles with (IC50) ≤ 500 while 39 conserved epitopes interacted with MHC-II alleles with IC50 ≤ 1000. Among all the tested epitopes for world population coverage the epitope FVGYVTTTF binding to both MHC1 and MHC11 alleles was 97.30% and it was found to bind 13 different alleles that indicate strong potential to formulate peptide vaccine for Lagos rabies virus.

Keywords: Immunoinformatic; Lagos rabies virus; Glycoprotein G; Lyssavirus; Peptide vaccine; Epitope

Introduction

Rabies is zoonotic disease distributed globally and caused by 11 viral species belonging to single-stranded RNA virus from the Lyssavirus genus related to the family Rhabdoviridae [1,2]. The genus Lyssavirus includes classical rabies virus (Rabies virus (RABV), Lagos bat virus (LBV), Duvenhage virus (DUVV), Mokola virus (MOKV) and Shimoni bat virus (SHIBV) were isolated in Africa, while LBV, MOKV, DUVV and SHIBV exist exclusively in Africa [3]. Complex phylogeny of Lagos bat virus was demonstrated in recent studies [4]. The original isolate of LBV in Nigeria since 1956 was genetically distant from other LBV isolates found up to date. The two viruses originating from Senegal (1985) and found in France (was introduced via Togo or Egypt; 1999) makes another phylogenetic lineage and they were found similar to each other, where a third lineage is formed by isolates from Ethiopia, Zimbabwe, the Central African Republic and South Africa from 1974 to 2006 and the genetic distances between these lineages are greater than those found with other lyssavirus species [4]. This virus is able to infect all mammals and the disease causes thousands of human deaths every year mainly in Asia and Africa where the virus circulates endemically in domestic dogs (Canis lupus familiaris) [2]. The majority of these deaths (99%) are caused by bites from rabid dogs, causing continuous fear and threat to the suspected communities because the disease is invariably fatal but also preventable if managed earlier after infection, the role of domestic dogs as main vectors of rabies is recognized with little data about the dog-associated RABV variant than wild life variants such as skunk and raccoon RABVs circulating in North America [5]. These viruses are responsible for a meningo encephalomyelitis in mammals,transmission of the viruses to a healthy mammal occurs mainly through bite or scratch by an infected mammal (the saliva is the infectious material), bats are considered as the natural hosts of 10 of these viral species, however dogs are the main source of infection in humans with an estimate of 55,000 deaths per annum worldwide among which about 56% occurs in Asia and 44% in Africa [6]. The importance of geographical factors are well documented but are often neglected when measuring the economic load of the disease [7,8]. Since 2005 more data has become available and the global disease situation changed markedly with good control efforts in some parts of the world that leads to rabiesfree countries but increased number of cases in other parts of the world was recorded [9-12]. Although there is no effective treatment after declaration of the disease, there is an effective management against RABV and related lyssaviruses when applied as soon as possible after exposure, it consists of local treatment of the wound, administration of rabies immunoglobulin (if indicated) and vaccinations against rabies that is able to prevent the onset of symptom and death [13]. Moreover, even with well-studied and documented epidemic expansions of wildlife RABV, there is little to know about the spread of rabies in endemic areas [14]. The replication potentials of various lyssaviruses looks different in a given host and the genome organization is highly conserved [15,16]. While the envelope components matrix protein M and glycoprotein G are required for virus release and virus infectivity, respectively [17]. Based on receptor binding and the apoptosis-inducing properties of the sole RABV surface antigen, Glycoprotein G has been designated as the major pathogenicity determinant of genotype 1 lyssaviruses [18,19]. However, many examples of glycoprotein G-independent mechanisms of virus-cell interaction exist, among which those involved in escape from antiviral innate immunity and to be important for in vivo virus replication [20-25]. The nucleotide substitution rate of lyssaviruses is estimated to be around 10−4 per site per year [26]. The RNA-dependent RNA-polymerase together with phosphoprotein (P), functions as the transcriptase and replicase complex, the glycoprotein G is the only outer membrane protein responsible for virus entry and inducing protective immune responses [27]. The role of vaccines is to generate an immune response in order to protect the vaccinated individual upon future exposures to the disease [28]. There is considerable differences in Individuals immune systems that in some cases individual’s immune system will not respond adequately to protect against second exposure and this is one of the reasons explaining the failure of immunization [28]. Vaccine production that depends on biochemical experiments are time consuming, expensive and not always work, furthermore this type of vaccines might constitutes a few hundred of unnecessary proteins for the induction of immunity causing many reactogenic or allergic responses [29,30]. Therefore, Insilco prediction of epitopes of appropriate protein residues would help in production of peptide based vaccines with powerful immunogenic and minimal allergenic effect [29]. Our aim is to design a vaccine for Lagos Rabies virus using peptides of its glycoprotein G as an immunogen to stimulate protective immune response.

Materials And Methods

Protein sequence retrieval

A total of 26 strains of rabies Lagos virus strains’ glycoprotein were retrieved from NCBI (https://www.ncbi.nlm.nih.gov/protein). Database in November 2016. These 26 strains sequences retrieved are from different areas around the world (include 10 collected from South Africa, 6 from Nigeria, 3 from Senegal, 3 from Kenya, one from Zimbabwe, one from central Africa public and two samples were collected from collaborative laboratories).

Retrieved glycoprotein sequences with their accession number, date of collection and areas of collection were listed in Table 1.

Accession Number Date of collection Country
*YP_007641390.1 1985 Senegal
ABZ81170.1 1956 Nigeria
ABZ81160.1 1985 Senegal
AMR44684.1 1986 Nigeria
ADD84515.1 2009 Kenya
ABU87631.1 1985 Senegal
ABU87630.1 1999 South Africa
ABU87629.1 1956 Nigeria
ABU87628.1 1947 Central Africa Republic
ABU87627.1 1986 Zimbabwe
ABU87626.1 2004 South Africa
ABU87625.1 1980 South Africa
ABU87624.1 1980 South Africa
ABU87623.1 1982 South Africa
ABU87622.1 1980 South Africa
ABU87621.1 2004 South Africa
ABU87620.1 2006 South Africa
ABU87619.1 2003 South Africa
AAN63563.1 1956 Nigeria
AEE36616.1 2008 South Africa
AFW16649.1ADQ01807.1 ABY86624.1Q8BDV6.1AAK97864.1AAK97863.1 2010
1956
2010
1956
**
**
Kenya
Nigeria
Kenya
Nigeria
**
**

* Ref sequence.
** Collaborative Laboratories.

Table 1: Virus strains retrieved, their Accession numbers, date of collection and area of collection.

Conserved regions determination

The retrieved sequences were aligned to obtain conserved regions using multiple sequence alignment (MSA), sequences aligned using Clustal-W as Applied in the Bio-Edit program, version 7.0.9.1 (Hall, 1999) to find out the conserved regions in all 26 retrieved Rabies glycoprotein G sequences [31]. Then the candidate epitopes were analyzed by different prediction tools from Immune Epitope Database IEDB analysis resource (http://www.iedb.org/) [32].

B-cell epitope prediction

The reference sequence of glycoprotein was subjected to different B cell tests [33].

Prediction of linear B-cell epitopes: Bepipred test from immune epitope database (http://tools.iedb.org/bcell/result/) [34], was used as linear B-cell epitopes prediction from the conserved region with a default threshold value of 0.148.

Prediction of surface accessibility: By using Emini surface accessibility prediction tool of the immune epitope database (IEDB) (http://tools.iedb.org/bcell/result/) [35]. The surface epitopes were predicted from the conserved region with the default threshold value 1.0.

Prediction of epitopes antigenicity: Using Kolaskar and Tongaonkar antigenicity method to determine the antigenic sites with a default threshold value of 1.042, (http://tools.iedb.org/bcell/result/) [36].

MHC class I binding predictions

Analysis of peptide binding to MHC1 molecules was assessed by the IEDB MHC I prediction tool at http://tools.iedb.org/mhc1. The attachment of cleaved peptides to MHC molecules was predicted using artificial neural network (ANN) method [37,38] . Prior to prediction, all epitope lengths were set as 9 mers, all conserved epitopes that bind to MHC1 alleles at score equal or less than 500 half-maximal inhibitory concentrations (IC50) were selected for further analysis [37].

MHC class II binding predictions

Analysis of peptide binding to MHC II molecules was assessed by the IEDB MHC II prediction tool at (http://tools.iedb.org/mhcii/ result/ [37]. For MHC II binding predication, human allele references set were used. MHC II groove has the ability to bind different lengths peptides that makes prediction more difficult and less accurate [38]. We used artificial neural networks to identify both the binding affinity and MHC II binding core epitopes. All conserved epitopes that bind to many alleles at score equal or less than 1000 half-maximal inhibitory concentration (IC50) were selected for further analysis [39].

Population coverage calculation

All proposed MHC I and MHC II epitopes from Lagos rabies virus glycoprotein G was assessed for population coverage to the whole world population with the selected MHC I and MHC II binding alleles using IEDB population coverage calculation tool at http://tools.iedb.org/ tools/population/iedb_input [40].

Homology modeling

The reference sequence of Lagos rabies glycoprotein to Raptor X on 21/12/2016, the 3D structure of glycoprotein was received on 22/12/2016 and then treated with chimera software to show the position of proposed peptides [41-45].

Results

B-cell epitope prediction

The reference sequence of Lagos rabies virus glycoprotein (GP) was subjected to Bepipred linear epitope prediction, Emini surface accessibility and Kolaskar and Tongaonkar antigenicity methods in IEDB, to determine the epitope linearity, being in the surface and to test the immunogenicity respectively Tables 2,3 and Figures 1-4.

immunome-research-red-line

Figure 1: Bepipred Linear Epitope Prediction; Yellow areas above threshold (red line) are proposed to be a part of B cell epitopes and the green areas are not.

immunome-research-red-surface

Figure 2: Emini surface accessibility prediction; Yellow areas above threshold (red line) are proposed to be a part of B cell epitopes and the green areas are not.

immunome-research-while-green

Figure 3: Kolaskar and Tongaonkar antigenicity prediction; Yellow areas above threshold (red line) are proposed to be a part of B cell epitope while green areas are not.

immunome-research-rabies-virus

Figure 4: Structural position of the most promising conserved B cell epitopes of glycoprotein G of Lagos rabies virus.

Prediction of Cytotoxic T-lymphocyte epitopes and interaction with MHC

The reference sequence of glycoprotein G of Lagos rabies virus was analyzed using IEDB MHC-1 binding prediction tool to predict T cell epitopes suggested to interact with different types of MHC I alleles based on ANN- align with (IC50) ≤ 500, the list of conserved epitopes and their corresponding MHC-1 alleles are shown in Table 4 and Figure 5.

Peptide Start End Length Emini Score Antigenicity Score
LYTIPE 23 28 6 0.908 1.065
QKV 73 75 3 1.288 1.109
GFTCT 77 81 5 0.309 1.039
EAVT 86 89 4 0.754 1.052
TTFKRKHFKPT 99 109 11 6.55 0.976
KPT 112 114 3 2.236 0.986
SGDPRYEESLHTPYP 122 137 15 9.442 1.008
SWLRTVTTTK 139 148 10 1.614 0.998
RTLHSPMFP 166 174 9 1.181 1.022
FYPS 181 184 4 1.131 1.082
TNHD 190 193 4 2.121 0.914
LWLP 196 199 4 0.445 1.114
MNGS 220 223 4 0.849 0.872
MCGFTDERG 225 233 9 0.499 0.953
GLRL 251 254 4 0.53 1.062
QLVN 275 278 4 0.686 1.106
NNR 281 283 3 2.538 0.808
VPGYGKAYT 327 335 9 1.091 1.047
VHY 346 348 3 0.793 1.216
DIL 356 358 3 0.358 1.089
IKG 383 385 3 0.693 0.985
KDGDAD 427 432 6 2.451 0.911

Table 2: List of conserved peptides with their surface accessibility score and antigenicity score.

immunome-research-Lagos-rabies

Figure 5: Structural Position of the two most promising conserved epitopes at glycoprotein G of Lagos rabies virus that interact with MHC I alleles.

Epitope Start End Length Surface accessibility score Antigenicity score
VPGYGKAYT 327 335 9 1.091 1.047
FYPS 181 184 4 1.131 1.082
QKV 73 75 3 1.288 1.109

Table 3: List of conserved peptide that passes Bepipred, Emini surface and Koalaskar tests with their length and scores

Peptide Start End Alleles IC 50 Percentile rank
EAVTYTNFV 86 94 HLA-A*68:02 3.47 0.2
VTYTNFVGY 88 96 HLA-A*11:01 36.63 0.4
      HLA-A*29:02 14.58 0.2
      HLA-A*30:02 43.58 0.2
TYTNFVGYV 89 97 HLA-C*14:02 96.3 0.3
FVGYVTTTF 93 101 HLA-B*15:01 99.41 0.2
      HLA-B*35:01 18.33 0.2
      HLA-C*12:03 87.09 0.2
VGYVTTTFK 94 102 HLA-A*03:01 46.59 0.2
      HLA-A*11:01 82.1 0.4
GYVTTTFKR 95 103 HLA-A*31:01 47.13 0.4
TTFKRKHFK 99 107 HLA-A*03:01 17.37 0.2
      HLA-A*11:01 11.73 0.3
      HLA-A*30:01 53.78 0.5
      HLA-A*68:01 7.01 0.1
      HLA-A*31:01 15.2 0.3
FKRKHFKPT 101 109 HLA-B*08:01 99.49 0.2
YEESLHTPY 127 135 HLA-B*18:01 3.45 0.1
WLRTVTTTK 140 148 HLA-A*03:01 79.59 0.2
RTLHSPMFP 166 174 HLA-A*30:01 51.89 0.5
HFRKLVPGY 322 330 HLA-A*30:01 55.25 0.5
LVPGYGKAY 326 334 HLA-C*14:02 62.74 0.2

Table 4: List of conserved epitopes and their corresponding MHC-1 alleles along with their position in glycoprotein, IC50 and percentile rank.

Prediction of T helper cell epitopes and interaction with MHC II alleles

The reference sequence of glycoprotein G of Lagos rabies virus was analyzed using IEDB MHC II binding prediction tool based on NNalign with half-maximal inhibitory concentration (IC50) ≤ 1000; the list of all epitopes and their correspondent binding MHC II alleles were shown in (supplementary Table 1) while the list most promising three epitopes that had Binding affinity with MHC II alleles along with their positions in the glycoprotein G of Lagos rabies virus were shown in Table 5 and Figure 6.

Core Sequence Start End Peptide Sequence Allele IC50 Rank
FVGYVTTTF 93 101 TYTNFVGYVTTTFKR HLA-DPA1*01:03/DPB1*02:01 52.4 5.33
      TYTNFVGYVTTTFKR HLA-DPA1*02:01/DPB1*01:01 335.6 24.65
      VTYTNFVGYVTTTFK   429.2 28.33
      VTYTNFVGYVTTTFK HLA-DQA1*05:01/DQB1*02:01 821.8 17.42
      AVTYTNFVGYVTTTF   912.6 18.98
      YTNFVGYVTTTFKRK HLA-DRB1*04:01 26.2 1.54
      TYTNFVGYVTTTFKR   27.7 1.68
      VTYTNFVGYVTTTFK   32.3 2.12
      AVTYTNFVGYVTTTF   36.8 2.55
      TNFVGYVTTTFKRKH   39 2.76
      NFVGYVTTTFKRKHF   52.8 4.08
      FVGYVTTTFKRKHFK   83 6.73
      YTNFVGYVTTTFKRK HLA-DRB1*01:01 89.4 28.65
      TNFVGYVTTTFKRKH   198.1 40.73
      NFVGYVTTTFKRKHF   314.7 48.97
      VTYTNFVGYVTTTFK HLA-DRB1*07:01 47.4 8.32
      TYTNFVGYVTTTFKR   61.4 10.11
      AVTYTNFVGYVTTTF   62 10.19
      YTNFVGYVTTTFKRK HLA-DRB1*04:04 62.4 7.41
      TYTNFVGYVTTTFKR   66.9 8.02
      YTNFVGYVTTTFKRK HLA-DRB1*04:05 82.1 8.06
      TYTNFVGYVTTTFKR   83.9 8.22
      VTYTNFVGYVTTTFK   94.1 9.12
      TNFVGYVTTTFKRKH   94.5 9.16
      TNFVGYVTTTFKRKH HLA-DRB1*08:02 112 1.93
      YTNFVGYVTTTFKRK   112.5 1.94
      AVTYTNFVGYVTTTF HLA-DRB1*04:05 119.7 11.21
      TYTNFVGYVTTTFKR HLA-DRB1*09:01 131.2 8.94
      AVTYTNFVGYVTTTF HLA-DRB1*04:04 133.1 15.1
      NFVGYVTTTFKRKHF HLA-DRB1*08:02 136.2 2.61
      YTNFVGYVTTTFKRK HLA-DRB1*09:01 137.6 9.33
      VTYTNFVGYVTTTFK   143.6 9.71
      TYTNFVGYVTTTFKR HLA-DRB1*08:02 146.2 2.89
      NFVGYVTTTFKRKHF HLA-DRB1*07:01 148.7 18.1
      NFVGYVTTTFKRKHF HLA-DRB1*04:05 153.6 13.63
      AVTYTNFVGYVTTTF HLA-DRB1*09:01 159.3 10.64
      TNFVGYVTTTFKRKH   172.5 11.44
      FVGYVTTTFKRKHFK HLA-DRB1*07:01 214.7 22.18
      VTYTNFVGYVTTTFK HLA-DRB1*08:02 216.1 4.82
      FVGYVTTTFKRKHFK HLA-DRB1*04:05 243.7 18.96
      NFVGYVTTTFKRKHF HLA-DRB1*09:01 269.1 16.34
      FVGYVTTTFKRKHFK HLA-DRB1*04:04 316.5 27.12
      AVTYTNFVGYVTTTF HLA-DRB1*08:02 331 7.92
      FVGYVTTTFKRKHFK   347.1 8.33
      FVGYVTTTFKRKHFK HLA-DRB1*09:01 393.5 21.68
      TNFVGYVTTTFKRKH HLA-DRB1*15:01 134.1 12.67
      TYTNFVGYVTTTFKR   135 12.73
      NFVGYVTTTFKRKHF   148.7 13.7
      YTNFVGYVTTTFKRK   151.2 13.87
      VTYTNFVGYVTTTFK   163.8 14.72
      FVGYVTTTFKRKHFK   188.4 16.28
      AVTYTNFVGYVTTTF   198.6 16.88
      AVTYTNFVGYVTTTF HLA-DRB3*01:01 423.1 10.64
      VTYTNFVGYVTTTFK   495.5 11.68
      AVTYTNFVGYVTTTF   552.6 34.42
      TYTNFVGYVTTTFKR   590.5 12.96
      YTNFVGYVTTTFKRK   753.5 14.99
FRKLVPGYG 323 331 RLSHFRKLVPGYGKA HLA-DQA1*05:01/DQB1*03:01 368.2 31.01
      RRLSHFRKLVPGYGK HLA-DQA1*05:01/DQB1*03:01 513.7 36.21
      FRRLSHFRKLVPGYG   584.4 38.4
      LSHFRKLVPGYGKAY HLA-DRB1*01:01 5.1 0.88
      RLSHFRKLVPGYGKA   6.5 2.18
      SHFRKLVPGYGKAYT   6.7 2.37
      HFRKLVPGYGKAYTI   8.8 4.22
      RRLSHFRKLVPGYGK   9 4.39
      FRKLVPGYGKAYTIL   12.1 6.74
      FRRLSHFRKLVPGYG   14 7.99
      LSHFRKLVPGYGKAY HLA-DRB1*09:01 26.3 1.28
      SHFRKLVPGYGKAYT   31.3 1.66
      RLSHFRKLVPGYGKA   34.8 1.94
      FRRLSHFRKLVPGYG   41.6 2.55
      HFRKLVPGYGKAYTI   42.8 2.66
      RRLSHFRKLVPGYGK   45.4 2.87
      FRKLVPGYGKAYTIL   56.4 3.74
      RRLSHFRKLVPGYGK HLA-DRB1*04:04 155.3 16.91
      RLSHFRKLVPGYGKA   160.4 17.31
      FRRLSHFRKLVPGYG   169.4 18.01
      LSHFRKLVPGYGKAY   173.8 18.38
      SHFRKLVPGYGKAYT   274.6 24.92
      HFRKLVPGYGKAYTI   328.5 27.74
      FRRLSHFRKLVPGYG HLA-DRB1*08:02 567.4 13.75
      RRLSHFRKLVPGYGK HLA-DRB1*07:01 592.9 35.83
      RRLSHFRKLVPGYGK HLA-DRB1*08:02 598.9 14.46
      RLSHFRKLVPGYGKA   662.8 15.81
      FRKLVPGYGKAYTIL HLA-DRB1*04:04 714.7 41.07
      RLSHFRKLVPGYGKA HLA-DRB1*07:01 858.8 41.76
      RRLSHFRKLVPGYGK HLA-DRB1*04:05 890.7 39.23
      LSHFRKLVPGYGKAY HLA-DRB1*07:01 905.7 42.64
      LSHFRKLVPGYGKAY HLA-DRB1*11:01 11.6 1.7
      RLSHFRKLVPGYGKA   15.9 2.68
      SHFRKLVPGYGKAYT   16.3 2.77
      RRLSHFRKLVPGYGK   21.7 3.93
      HFRKLVPGYGKAYTI   23.9 4.37
      FRKLVPGYGKAYTIL   38.7 6.92
      SHFRKLVPGYGKAYT HLA-DRB1*15:01 62.5 6.43
      LSHFRKLVPGYGKAY   116.8 11.32
      RRLSHFRKLVPGYGK   127.2 12.14
      RLSHFRKLVPGYGKA   130.4 12.38
      FRRLSHFRKLVPGYG   139.6 13.07
      LSHFRKLVPGYGKAY HLA-DRB5*01:01 6.5 1.31
      SHFRKLVPGYGKAYT   7.1 1.5
      RLSHFRKLVPGYGKA   9.7 2.28
      HFRKLVPGYGKAYTI   10 2.37
      RRLSHFRKLVPGYGK   15.3 3.79
      FRKLVPGYGKAYTIL   16 3.96
FKRKHFKPT 101 109 TTTFKRKHFKPTVSA HLA-DPA1*01/DPB1*04:01 222.9 9.14
      TTFKRKHFKPTVSAC   299 10.97
      TFKRKHFKPTVSACR   850 19.98
      VTTTFKRKHFKPTVS HLA-DPA1*01:03/DPB1*02:01 237.2 14.23
      TTTFKRKHFKPTVSA   289.8 15.95
      TTFKRKHFKPTVSAC   364.2 18.14
      TTTFKRKHFKPTVSA HLA-DRB1*01:01 545.1 58.11
      TTFKRKHFKPTVSAC   793.1 63.84
      FKRKHFKPTVSACRD HLA-DRB1*04:04 110.8 12.98
      TFKRKHFKPTVSACR   154.3 16.84
      TTFKRKHFKPTVSAC   318.2 27.22
      TTTFKRKHFKPTVSA   531 35.77
      VTTTFKRKHFKPTVS   733.7 41.54
      YVTTTFKRKHFKPTV HLA-DRB1*09:01 939.6 37.6
      TTTFKRKHFKPTVSA HLA-DRB1*11:01 73.7 11.28
      TTFKRKHFKPTVSAC   124.8 15.68
      TFKRKHFKPTVSACR   162.3 18.16
      FKRKHFKPTVSACRD   218.7 21.23
      TTTFKRKHFKPTVSA HLA-DRB5*01:01 124.5 17.25
      TTFKRKHFKPTVSAC   210.6 22.55

Table 5: List of most promising three epitopes that had Binding affinity with MHC II alleles along with their positions in the glycoprotein G of Lagos rabies virus, peptide sequence, binding alleles, IC50 and rank.

immunome-research-Lagos-rabies

Figure 6: Molecular position of the most promising three epitopes of Lagos rabies virus that binds MHC II alleles.

Population coverage analysis

Population coverage test was performed to detect the world coverage of all epitopes binds to MHC1 alleles, MHC11 alleles and combined MHC1 and MHC11 as well as selected most promising epitopes for each test.

Population coverage for MHC1: Population coverage results for all epitopes binding to MHC1 alleles of Lagos rabies virus was shown in supplementary Table (II) while the population coverage results of the most promising three peptides was shown on Table 6.

MHC1 peptides MHC11 Peptides
Epitope Coverage Epitope Coverage
FVGYVTTTF 35.42% FVGYVTTTF 97.30%
VTYTNFVGY 32.98% FRKLVPGYG 95.31%
VTYTNFVGY 32.98% FKRKHFKPT 95.31%
Epitope set 56.71%   99.68%

Table 6: Population coverage of most promising 3 epitopes binds to MHC1 alleles and MHC11 alleles of Lagos rabies virus along with their world population coverage.

Population coverage for MHC11: The population coverage results of all peptides binding to MHC11 alleles with their coverage and total HLA hits were shown in supplementary Table (III) and the results of most promising three epitopes were shown on Table 6.

Population coverage for both MHC1 and MHC11 alleles: This test was performed to the most promising epitope alone (FVGYVTTTF) and it was found to bind 13 alleles with population coverage of 97.30% Figure 7.

immunome-research-population-binds

Figure 7: Molecular position of the most promising epitope for population coverage that binds both MHC1 and MHC11 alleles.

Discussion

In the present study we proposed for the first time different selected peptides that could be recognized by B cell and T cell to produce antibodies against Lagos rabies virus. The resulting peptide vaccine is expected to be more antigenic and less allergic than the conventional biochemical vaccine.

The reference sequence of Lagos rabies virus glycoprotein G was subjected to Bepipred linear epitope prediction test, Emini surface accessibility test and Kolaskar and Tongaonkar antigenicity test in IEDB, to determine the binding to B cell, being in the surface and to test the immunogenicity respectively.

For Bepipred test there was 22 conserved epitopes that have the binding affinity to B cell while there are 11 epitopes predicted on the surface according to Emini surface accessibility test and 10 epitopes being antigenic as detected by Tongaonkar antigenicity test while only three epitopes (VPGYGKAYT, FYPS and QKV) found to overlap all performed B Cell tests.

Also the reference sequence of Lagos rabies virus glycoprotein G was analyzed using IEDB MHC1 binding prediction tool to predict T cell epitopes interacting with different types of MHC I alleles. Based on Artificial neural network (ANN) with half-maximal inhibitory concentration (IC50) ≤ 500; 23 conserved peptides were predicted to interact with different MHC-1 alleles. The peptide FVGYVTTTF from 93 to 101 had higher affinity to interact with 9 alleles (HLA-A*03:01, HLA-A*03:01, HLA-A*03:01, HLA-A*03:01, HLA-A*03:01, HLA-A*11:01, HLA-A*11:01, HLA-A*11:01, HLA-A*23:01), followed by VTYTNFVGY from 88 to 96 that binds 7 alleles (HLA-B*27:05, HLA-B*15:02, HLA-B*35:01, HLA-B*40:01, HLA-B*44:03, HLA-B*53:01, HLA-B*58:01). These two peptides could be thought about as a possible peptide vaccine for Lagos rabies virus.

The reference glycoprotein (GP) strain was analyzed using IEDB MHC II binding prediction tool based on NN-align with half-maximal inhibitory concentration (IC50) ≤ 1000; there were 39 conserved predicted epitopes found to interact with MHC-II alleles. The peptides FVGYVTTTF, FKRKHFKPT and FRKLVPGYG had the affinity to bind the highest number of MHC11 alleles.

World population coverage results for total epitopes binding to MHC1 alleles was 88,42% and the most promising peptides was FVGYVTTTF, VTYTNFVGY and VTYTNFVGY with world population coverage 56.71% and total HLA hits 3,7 and 7 respectively.

The world population coverage results for all epitopes that have binding affinity to MHC11 alleles was 99.97% while world population coverage of the most promising three epitopes FKRKHFKPT, FRKLVPGYG and FVGYVTTTF was 99.68 % with HLA hits 7,7 and 13 respectively.

The peptide FVGYVTTTF exhibits exceptional population coverage results for both MHC1 and MHC11 alleles of 97.3% with total HLA hits 13 different alleles.

Conclusion And Recommendations

Conclusion

We conclude that to our knowledge this was the first study to propose peptide vaccine for Lagos rabies virus which is expected to be more immunogenic and less allergic than traditional biochemical vaccines, among the different peptides tested for both B cell and T cell this study proposed an interesting T cell epitope (FVGYVTTTF) that have very strong binding affinity to both MHC1 and MHC11 alleles and it was found to bind 13 different alleles with world population coverage 97.3%, which indicates strong potential to formulate peptide vaccine for Lagos Rabies virus.

Recommendations

We recommend further studies to propose a peptide vaccines for the other strains of rabies virus especially Rabies lyssavirus, there will be possibility to find common conserved promising epitopes for multiple strains. Also we recommend in vitro and in vivo evaluation of the most promising peptides.

References

Citation: Ahmed OH, Abdelhalim A, Obi S, Abd_elrahman KA, Hamdi A, et al. (2017) Immunoinformatic Approach for Epitope-Based Peptide Vaccine against Lagos Rabies Virus Glycoprotein G. Immunome Res 13: 137. Doi: 10.4172/1745-7580.1000137

Copyright: © 2017 Ahmed OH, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Select your language of interest to view the total content in your interested language

Post Your Comment Citation
Share This Article
Relevant Topics
Article Usage
  • Total views: 960
  • [From(publication date): 0-2017 - Sep 26, 2018]
  • Breakdown by view type
  • HTML page views: 898
  • PDF downloads: 62

Post your comment

captcha   Reload  Can't read the image? click here to refresh
Leave Your Message 24x7