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Review
. 2016 Aug:76:20-30.
doi: 10.1016/j.jobaz.2016.08.002. Epub 2016 Nov 20.

Current situation, genetic relationship and control measures of infectious bronchitis virus variants circulating in African regions

Khadija Khataby  1   2 , Amal Souiri  1 , Yassine Kasmi  1 , Chafiqa Loutfi  2 , My Mustapha Ennaji  1
Affiliations
Review

Current situation, genetic relationship and control measures of infectious bronchitis virus variants circulating in African regions

Khadija Khataby et al. J Basic Appl Zool. 2016 Aug.

Abstract

Infectious bronchitis virus (IBV) is a major viral pathogen of commercial poultry, affecting chickens of all ages and causing major economic losses in poultry industry worldwide. Frequent points of mutations and recombination events in the S1 gene region, result in the emergence of new IBVs variants circulating in the form of several serotypes/genotypes that can be partially or poorly neutralized by current vaccines. IBV is well studied worldwide, nevertheless in African countries epidemiological and scientific data are poor and not updated. This review aims to give a current overview of IBV situation, to establish evolutionary relationship between the African variants and to list some of the potential measures to control IBV in Africa. Three S1 gene hypervariable regions were studied and compared to the reference genotypes/serotypes that found emerging in African regions. This comparison was based on phylogenetic trees, nucleotide and amino-acid sequence analysis. It clearly appears that IBV variants reported in Africa, display a low genetic relationship between them and with the majority of the reference strains emerging in neighboring countries, except the case of variants from Libya and Egypt that show a high relatedness. Also the Massachusetts serotypes were the most prevalent co-circulating with both serotypes, Italy02 type in Morocco and Qx-like genotype in South part of the African continent. In order to control the IBV variants in African regions, an efficient vaccination strategy program should be implemented.

Keywords: HVR, hyper variable region; Hypervariable regions (HVR); IB, infectious bronchitis; IBV, infectious bronchitis virus; Infectious bronchitis virus; M, membrane; N, nucleocapsid; Phylogenetic analysis; S, spike; S1 gene; nt, nucleotide.

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Figures

Fig. 1
Fig. 1
Phylogenetic tree of all IBV variant isolated from different parts in Africa. The tree analysis is based on comparison of the partial nucleotide sequence of the S1 gene containing the highly variable regions HVR1 and HVR 2 (located between 146 and 546 nucleotide) showing the relationship between the African IBV variants and selected reference strains. The phylogenetic tree analysis was conducted by the neighbor-joining (Kimura two-parameter) method with 1000 bootstrap replicates implemented in Neighbor from the PHYLIP package (v3.66). Numbers along the branches refer to bootstrap values.
Fig. 2
Fig. 2
Phylogenetic tree of all IBV variant isolated from different parts in Africa. The tree analysis is based on comparison of the partial nucleotide sequence of the S1 gene containing the highly variable regions HVR3 (located between 760 and 987 nucleotides) showing the relationship between the African IBV variants and selected reference strains. The phylogenetic tree analysis was conducted by the neighbor-joining (Kimura two-parameter) method with 1000 bootstrap replicates implemented in Neighbor from the PHYLIP package (v3.66). Numbers along the branches refer to bootstrap values.
Fig. 3
Fig. 3
Phylograms of HVR regions demonstrating the diversity of different IBV strains. The figure on the right shows the phylogeny of HRV1 and HVR 2 region, then left is the phylogram of HVR3. In both figures the presence of two lines is observed.
Fig. 4
Fig. 4
Sequence alignment of amino acid of S1 gene showing highly conserved regions (in white) and non conserved regions (in black) in the HVR1 and 2.
See this image and copyright information in PMC

References

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