Browsing by Author "Carulei, Olivia"

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    Comparative analysis of avian poxvirus genomes, including a novel poxvirus from lesser flamingos (Phoenicopterus minor), highlights the lack of conservation of the central region
    (BioMed Central, 2017-12-06) Carulei, Olivia; Douglass, Nicola; Williamson, Anna-Lise
    Background: Avian poxviruses are important pathogens of both wild and domestic birds. To date, seven isolates from subclades A and B and one from proposed subclade E, have had their genomes completely sequenced. The genomes of these isolates have been shown to exhibit typical poxvirus genome characteristics with conserved central regions and more variable terminal regions. Infection with avian poxviruses (APVs) has been reported in three species of captive flamingo, as well as a free-living, lesser flamingo at Kamfers dam, near Kimberley, South Africa. This study was undertaken to further characterise this virus which may have long term effects on this important and vulnerable, breeding population. Results: Gene content and synteny as well as percentage identities between conserved orthologues was compared between Flamingopox virus (FGPV) and the other sequenced APV genomes. Dotplot comparisons revealed major differences in central regions that have been thought to be conserved. Further analysis revealed five regions of difference, of differing lengths, spread across the central, conserved regions of the various genomes. Although individual gene identities at the nucleotide level did not vary greatly, gene content and synteny between isolates/species at these identified regions were more divergent than expected. Conclusion: Basic comparative genomics revealed the expected similarities in genome architecture but an in depth, comparative, analysis showed all avian poxvirus genomes to differ from other poxvirus genomes in fundamental and unexpected ways. The reasons for these large genomic rearrangements in regions of the genome that were thought to be relatively conserved are yet to be elucidated. Sequencing and analysis of further avian poxvirus genomes will help characterise this complex genus of poxviruses.
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    Genetic and phenotypic analysis of novel South African Avian poxviruses
    (2018) Carulei, Olivia; Williamson, Anna-Lise; Douglass, Nicola
    Avian poxviruses are important pathogens of both wild and domestic birds and exhibit a large degree of intragenus diversity at a genomic level. These viruses are known to differ in growth characteristics (in vitro and in vivo), virulence, and cross-protection, with little known about the genomic contributions to these differences. Only six isolates from subclades A and B and one from proposed subclade E have had their genomes completely sequenced. These genomes have been shown to exhibit typical poxvirus genome characteristics with conserved central regions and more variable terminal regions, however all isolates exhibit major differences in defined central regions. This study aimed to analyze and characterize novel isolates from South Africa in terms of growth characteristics and phylogenetic relationships. It also added to the pool of genome sequences available for comparative genomic analyses to further investigate genome architecture. Poxvirus isolates from lesser flamingo (Phoenicopterus minor) and African penguin (Spheniscus demersus) were chosen for analysis from a larger pool of donated isolates by comparison of macroscopic growth characteristics on chorioallantoic membranes, membrane histology and phylogenetic analyses based on nucleotide alignment of partial P4b sequences. Flamingopox virus was shown to group in subclade A3, induce membrane thickening and mesodermal hyperplasia while Penguinpox virus grouped in subclade A2, and did not induce membrane thickening or hyperplasia. The genomes of the above isolates were sequenced and compared to other available avipoxvirus genomes. Dotplot comparisons revealed major differences in central regions that have traditionally been thought to be conserved. Further analysis revealed five regions of difference, of varying lengths, spread across the central regions of the various genomes. Although individual gene identities at the nucleotide level did not vary greatly, gene content and synteny between isolates/species at these identified regions were far more divergent than expected. The reasons for these large genomic rearrangements are yet to be elucidated and will need to be considered in future phylogenetic studies and vaccine vector design. Sequencing and analysis of further avian poxvirus genomes will help characterize this complex genus of poxviruses.
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    Genetic characterisation of six novel African swine fever viruses isolated from a pig, warthog, wild boar, and ticks
    (2021) Ndlovu, Sandy Sibusiso; Williamson, Anna-Lise; Carulei, Olivia; Heath, Livio
    African swine fever (ASF) is a disease that affects domestic pigs and wild boars, resulting in up to 100% case fatality rate, and there is currently no effective treatment or vaccine. To date, there are 67 ASFV complete genome sequences available, but most of the sequences represent only genotypes I-V and VII-X of the 24 genotypes identified based on p72 sequencing, limiting inter and intra-genotype comparative studies. ASFVs encode several multigene families (MGFs) involved in virulence and host range which are found at the genomic termini and the majority of genomic differences between isolates are due to the composition of these MGFs. The comparison of the MGFs across ASFV isolates is of utmost importance in understanding genome variability and their contribution to virulence. The p72 gene has historically been used in phylogenetic analysis of ASFV. However, it lacks the capacity for higher resolution between isolates belonging to the same genotype. This study aimed to analyse and characterise six novel ASFV isolates of African origin from a domestic pig, warthog, wild boar and ticks in terms of genomic makeup, MGF composition and phylogenetic relationships, including identification of additional phylogenetic markers, specifically for use in discrimination between closely related isolates. Genomes of six novel isolates were sequenced and annotated by identifying open reading frames (ORFs) with a methionine START codon and performing BLASTx searches of each ORF against the NCBI data base. Differences between the genomes were analysed by generating dotplots and using Base-By-Base which showed them to be mostly collinear, but regions of difference were observed at the termini and the CCR. MGF analysis using sorting and clustering in Morpheus software, based on genotype, serogroup, country, host, virulence, and year, showed that genotype and serogroup play a role in the MGF arrangement patterns. Loci corresponding to regions of difference in the CCR were used for phylogenetic comparison to the previously identified marker p72. The tree topology of all of the alternative phylogenies differed from the current p72 classification. B117L and B169L provided slightly better resolution of genotypes I and II, respectively, and viruses from East Africa that are classified as belonging to genotype IX based on p72 were separated when using EP364R. This data adds to the pool of diverse ASFV isolates available for comparative genomics studies, and to the knowledge of ASFV in Africa. The sequencing of more diverse ASFV isolates of each genotype will help characterise the MGFs arrangement patterns among isolates. The novel alternative phylogenetic markers should further be investigated using more ASFV isolates representing the 24 genotypes described to date.
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    Phylogenetic analysis of three genes of Penguinpox virus corresponding to Vaccinia virus G8R (VLTF-1), A3L (P4b) and H3L reveals that it is most closely related to Turkeypox virus, Ostrichpox virus and Pigeonpox virus
    (BioMed Central Ltd, 2009) Carulei, Olivia; Douglass, Nicola; Williamson, Anna-Lise
    Phylogenetic analysis of three genes of Penguinpox virus, a novel Avipoxvirus isolated from African penguins, reveals its relationship to other poxviruses. The genes corresponding to Vaccinia virus G8R (VLTF-1), A3L (P4b) and H3L were sequenced and phylogenetic trees (Neighbour-Joining and UPGMA) constructed from MUSCLE nucleotide and amino acid alignments of the equivalent sequences from several different poxviruses. Based on this analysis, PEPV was confirmed to belong to the genus Avipoxvirus, specifically, clade A, subclade A2 and to be most closely related to Turkeypox virus (TKPV), Ostrichpox virus (OSPV)and Pigeonpox virus (PGPV).
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    Six host-range restricted poxviruses from three genera induce distinct gene expression profiles in an in vivo mouse model
    (BioMed Central Ltd, 2015) Offerman, Kristy; Deffur, Armin; Carulei, Olivia; Wilkinson, Robert; Douglass, Nicola; Williamson, Anna Lise
    BACKGROUND: Host-range restricted poxviruses make promising vaccine vectors due to their safety profile and immunogenicity. An understanding of the host innate immune responses produced by different poxvirus vectors would aid in the assessment, selection and rational design of improved vaccines for human and veterinary applications. Novel avipoxviruses are being assessed to determine if they are different from other poxvirus vectors. Analysis of the transcriptome induced in a mouse model would aid in determining if there were significant differences between different poxvirus vectors which may reflect different adjuvant potential as well as establish if they should be further evaluated as vaccine vectors. RESULTS: We compared host transcript abundance in the spleens of BALB/c mice twenty four hours after intravenous infection (10 5 pfu/mouse) with six host-restricted poxvirus species from three genera, namely Lumpy Skin Disease virus (LSDV), Canarypox virus (CNPV), Fowlpox virus (FWPV), modified vaccinia Ankara (MVA) and two novel South African avipoxviruses, Feral Pigeonpox virus (FeP2) and Penguinpox virus (PEPV). These six viruses produced qualitatively and quantitatively distinct host responses with LSDV, followed by MVA, inducing the greatest interferon (IFN) response. FeP2 and PEPV caused very little change to host transcript abundance compared to the other 4 viruses tested. CNPV and FWPV induced the up regulation of two immunoglobulin genes (Ighg and Ighg3 (IgG3)) with CNPV inducing a third, Ighm (IgM). HIV-1-specific IgG3 antibodies have been correlated with decreased risk of HIV-1 infection in the RV144 trial, which included a CNPV-based vector (Yates et al. (Sci Transl Med, 6(228) p228, 2014). Up regulation of IgG3 by CNPV and FWPV but not the other poxviruses tested in vivo, implies that these two avipoxvirus-vector backbones may be involved in stimulation of the clinically important IgG3 antibody subclass. Differential transcript abundance associated with the different poxviruses is further discussed with particular emphasis on responses related to immune responses. CONCLUSION: Six, genetically diverse host-restricted poxviruses produce different responses in a mouse model early after infection. These differences may affect the immune response induced to vaccine antigen in vectors based on these viruses. The two novel avipoxviruses were clearly distinguishable from the other viruses.