James Nyagwange 1, 3, Nicola Ternette 2, Edwin Tijhaar 3, Roger Pelle’ 4, Vish Nene 5 1, 4, 5 Int... more James Nyagwange 1, 3, Nicola Ternette 2, Edwin Tijhaar 3, Roger Pelle’ 4, Vish Nene 5 1, 4, 5 International Livestock Research Institute, P. O. Box 30709, Nairobi, Kenya 2 The Jenner Institute, Nuffield Department of Medicine, University of Oxford, UK 3 Cell Biology and Immunology Group, Wageningen University, The Netherlands Introduction East Coast fever (ECF) is a lymphoproliferative disease caused by the protozoan parasite Theileria parva. It kills about one million cattle annually in Africa. The sporozoite stage of this parasite, harbored in the salivary glands of the tick Rhipicephalus appendiculatus, invades and establishes infection in the bovine lymphocytes during tick feeding. However, little is known about the parasite molecules involved in this infection process. It is therefore necessary to elucidate the protein composition of the sporozoites to identify novel targets for blocking invasion. Blocking this initial stage of invasion presents a promising vaccine strategy for...
The parasiteTheileria parvais the causative agent of East Coast fever (ECF), one of the most seri... more The parasiteTheileria parvais the causative agent of East Coast fever (ECF), one of the most serious cattle diseases in sub-Saharan Africa, and directly impacts smallholder farmers’ livelihoods. There is an efficient live-parasite vaccine, but issues with transmission of vaccine strains, need of a cold chain, and antibiotics limit its utilization. This has fostered research towards subunit vaccination. Cytotoxic T lymphocytes (CTL) are crucial in combating the infection by lysingT. parva-infected cells. Tp1 is an immunodominant CTL antigen, which induces Tp1-specific responses in 70–80% of cattle of the A18 or A18v haplotype during vaccination with the live vaccine. In this study, human adenovirus serotype 5 (HAd5) and modified vaccinia Ankara (MVA) were assessed for their ability to induce Tp1-specific immunity. Both viral vectors expressing the Tp1 antigen were inoculated in cattle by a heterologous prime-boost vaccination regimen. All 15 animals responded to Tp1 as determined by ...
The extent of sequence diversity among the genes encoding 10 antigens (Tp1–10) known to be recogn... more The extent of sequence diversity among the genes encoding 10 antigens (Tp1–10) known to be recognized by CD8+T lymphocytes from cattle immune toTheileria parvawas analysed. The sequences were derived from parasites in 23 buffalo-derived cell lines, three cattle-derived isolates and one cloned cell line obtained from a buffalo-derived stabilate. The results revealed substantial variation among the antigens through sequence diversity. The greatest nucleotide and amino acid diversity were observed in Tp1, Tp2 and Tp9. Tp5 and Tp7 showed the least amount of allelic diversity, and Tp5, Tp6 and Tp7 had the lowest levels of protein diversity. Tp6 was the most conserved protein; only a single non-synonymous substitution was found in all obtained sequences. The ratio of non-synonymous: synonymous substitutions varied from 0.84 (Tp1) to 0.04 (Tp6). Apart from Tp2 and Tp9, we observed no variation in the other defined CD8+ T cell epitopes (Tp4, 5, 7 and 8), indicating that epitope variation is...
International journal for parasitology, Jul 11, 2016
An infection and treatment protocol is used to vaccinate cattle against Theileria parva infection... more An infection and treatment protocol is used to vaccinate cattle against Theileria parva infection. Due to incomplete cross-protection between different parasite isolates, a mixture of three isolates, termed the Muguga cocktail, is used for vaccination. While vaccination of cattle in some regions provides high levels of protection, some animals are not protected against challenge with buffalo-derived T. parva. Knowledge of the genetic composition of the Muguga cocktail vaccine is required to understand how vaccination is able to protect against field challenge and to identify the potential limitations of the vaccine. The aim of the current study was to determine the extent of genetic and antigenic diversity within the parasite isolates that constitute the Muguga cocktail. High throughput multi-locus sequencing of antigen-encoding loci was performed in parallel with typing using a panel of micro- and mini-satellite loci. The former focused on genes encoding CD8(+) T cell antigens, bel...
Polymorphism of immunodominant CD8+ T cell epitopes can facilitate escape from immune recognition... more Polymorphism of immunodominant CD8+ T cell epitopes can facilitate escape from immune recognition of pathogens, leading to strain-specific immunity. In this study, we examined the TCR β-chain (TRB) diversity of the CD8+ T cell responses of cattle against two immunodominant epitopes from Theileria parva (Tp1214–224 and Tp249–59) and investigated the role of TCR recognition and MHC binding in determining differential recognition of a series of natural variants of the highly polymorphic Tp249–59 epitope by CD8+ T cell clones of defined TRB genotype. Our results show that both Tp1214–224 and Tp249–59 elicited CD8+ T cell responses using diverse TRB repertoires that showed a high level of stability following repeated pathogenic challenge over a 3-y period. Analysis of single-alanine substituted versions of the Tp249–59 peptide demonstrated that Tp249–59-specific clonotypes had a broad range of fine specificities for the epitope. Despite this diversity, all natural variants exhibited part...
ABSTRACTImmunity against the bovine intracellular protozoan parasiteTheileria parvahas been shown... more ABSTRACTImmunity against the bovine intracellular protozoan parasiteTheileria parvahas been shown to be mediated by CD8 T cells. Six antigens targeted by CD8 T cells fromT. parva-immune cattle of different major histocompatibility complex (MHC) genotypes have been identified, raising the prospect of developing a subunit vaccine. To facilitate further dissection of the specificity of protective CD8 T-cell responses and to assist in the assessment of responses to vaccination, we set out to identify the epitopes recognized in theseT. parvaantigens and their MHC restriction elements. Nine epitopes in sixT. parvaantigens, together with their respective MHC restriction elements, were successfully identified. Five of the cytotoxic-T-lymphocyte epitopes were found to be restricted by products of previously described alleles, and four were restricted by four novel restriction elements. Analyses of CD8 T-cell responses to five of the epitopes in groups of cattle carrying the defined restricti...
Proceedings of the National Academy of Sciences, 2006
East Coast fever, caused by the tick-borne intracellular apicomplexan parasiteTheileria parva, is... more East Coast fever, caused by the tick-borne intracellular apicomplexan parasiteTheileria parva, is a highly fatal lymphoproliferative disease of cattle. The pathogenic schizont-induced lymphocyte transformation is a unique cancer-like condition that is reversible with parasite removal. Schizont-infected cell-directed CD8+cytotoxic T lymphocytes (CTL) constitute the dominant protective bovine immune response after a single exposure to infection. However, the schizont antigens targeted byT. parva-specific CTL are undefined. Here we show the identification of five candidate vaccine antigens that are the targets of MHC class I-restricted CD8+CTL from immune cattle. CD8+T cell responses to these antigens were boosted inT. parva-immune cattle resolving a challenge infection and, when used to immunize naïve cattle, induced CTL responses that significantly correlated with survival from a lethal parasite challenge. These data provide a basis for developing a CTL-targeted anti-East Coast fever...
Background: African swine fever (ASF) is a lethal hemorrhagic disease affecting domestic pigs res... more Background: African swine fever (ASF) is a lethal hemorrhagic disease affecting domestic pigs resulting in up to 100 % mortality rates caused by the ASF virus (ASFV). The locally-adapted pigs in South-western Kenya have been reported to be resilient to disease and harsh climatic conditions and tolerate ASF; however, the mechanisms by which this tolerance is sustained remain largely unknown. We evaluated the gene expression patterns in spleen tissues of these locally-adapted pigs in response to varying infective doses of ASFV to elucidate the virus-host interaction dynamics. Methods: Locally adapted pigs (n=14) were experimentally infected with a high dose (1x106HAD50), medium dose (1x104HAD50), and low dose (1x102HAD50) of the highly virulent genotype IX ASFV Ken12/busia.1 (Ken-1033) isolate diluted in PBS and followed through the course of infection for 29 days. The in vivo pig host and ASFV pathogen gene expression in spleen tissues from 10 pigs (including three from each infectiv...
Swine leukocyte antigen (SLA) plays a central role in controlling the immune response by discrimi... more Swine leukocyte antigen (SLA) plays a central role in controlling the immune response by discriminating self and foreign antigens and initiating an immune response. Studies on SLA polymorphism have demonstrated associations between SLA allelic variants, immune response, and disease resistance. The SLA polymorphism is due to host-pathogen co-evolution resulting in improved adaptation to diverse environments making SLA a crucial genomic region for comparative diversity studies. Although locally-adapted African pigs have small body sizes, they possess increased resilience under harsh environmental conditions and robust immune systems with reported tolerance to some diseases, including African swine fever. However, data on the SLA diversity in these pigs are not available. We characterized the SLA of unrelated locally-adapted domestic pigs from Homa Bay, Kenya, alongside exotic pigs and warthogs. We undertook SLA comparative diversity of the functionally expressed SLA class I (SLA-1, SL...
Background African swine fever (ASF), a highly contagious hemorrhagic disease, affects domestic p... more Background African swine fever (ASF), a highly contagious hemorrhagic disease, affects domestic pigs in the Democratic Republic of Congo (DRC) where regular outbreaks are reported leading to high mortality rates approaching 100% in the affected regions. No study on the characteristics of the complete genome of strains responsible for ASF outbreaks in the South Kivu province of DRC is available, limited a better understanding of molecular evolution and spread of this virus within the country. The present study aimed at determining the complete genome sequence of ASFV strains genotype X involved in 2018–2019 ASF disease outbreaks in South Kivu province of DRC. Materials and methods Genomic DNA of a spleen sample from an ASFV genotype X-positive domestic pig in Uvira, during the 2018–2019 outbreaks in South Kivu, was sequenced using the Illumina HiSeq X platform. Obtained trimmed reads using Geneious Prime 2020.0.4 were blasted against a pig reference genome then contigs were generated...
Theileria parva is an economically important, intracellular, tick-transmitted parasite of cattle.... more Theileria parva is an economically important, intracellular, tick-transmitted parasite of cattle. A live vaccine against the parasite is effective against challenge from cattle-transmissible T. parva but not against genotypes originating from the African Cape buffalo, a major wildlife reservoir, prompting the need to characterize genome-wide variation within and between cattle- and buffalo-associated T. parva populations. Here, we describe a capture-based target enrichment approach that enables, for the first time, de novo assembly of nearly complete T. parva genomes derived from infected host cell lines. This approach has exceptionally high specificity and sensitivity and is successful for both cattle- and buffalo-derived T. parva parasites. De novo genome assemblies generated for cattle genotypes differ from the reference by ∼54K single nucleotide polymorphisms (SNPs) throughout the 8.31 Mb genome, an average of 6.5 SNPs/kb. We report the first buffalo-derived T. parva genome, whi...
Astroviruses (AstVs) are widely distributed and are associated with gastroenteritis in human and ... more Astroviruses (AstVs) are widely distributed and are associated with gastroenteritis in human and animals. The knowledge of the genetic diversity and epidemiology of AstVs in Africa is limited. This study aimed to characterize astroviruses in asymptomatic smallholder piglets in Kenya and Uganda. Twenty-four samples were randomly selected from a total of 446 piglets aged below 6 months that were initially collected for rotavirus study and sequenced for whole genome analysis. Thirteen (13/24) samples had contigs with high identity to genus Mamastrovirus. Analysis of seven strains with complete (or near complete) AstV genome revealed variable nucleotide and amino acid sequence identities with known porcine astrovirus (PoAstV) strains. The U083 and K321 strains had nucleotide sequence identities ranging from 66.4 to 75.4% with the known PoAstV2 strains; U460 strain had nucleotide sequence identities of 57.0 to 65.1% regarding the known PoAstV3; and K062, K366, K451, and K456 strains had ...
Background African swine fever (ASF) is a highly contagious and severe hemorrhagic viral disease ... more Background African swine fever (ASF) is a highly contagious and severe hemorrhagic viral disease of domestic pigs. The analysis of variable regions of African swine fever virus (ASFV) genome led to more genotypic and serotypic information about circulating isolates. The present study aimed at investigating the genetic diversity of ASFV strains in symptomatic pigs in South Kivu province of the Democratic Republic of Congo (DRC). Materials and Methods Blood samples collected from 391 ASF symptomatic domestic pigs in 6 of 8 districts in South Kivu were screened for the presence of ASFV, using a VP73 gene-specific polymerase chain reaction (PCR) with the universal primer set PPA1-PPA2. To genotype the isolates, we sequenced and compared the nucleotide sequences of PPA-positive samples at three loci: the C-terminus of B646L gene encoding the p72 protein, the E183L gene encoding the p54 protein, and the central hypervariable region (CVR) of the B602L gene encoding the J9L protein. In addi...
Despite the amount of resources deployed and technological advancements in Molecular Biology, vac... more Despite the amount of resources deployed and technological advancements in Molecular Biology, vaccinology, immunology, genetics, and biotechnology, there is still no effective vaccines against malaria. Immunity to either malaria or East Coast fever is usually seen as species- and/or strain-specific. But there is growing body of evidence suggesting the possibility of the existence of cross strain, cross species and cross genus immune responses in apicomplexans. The principle of gene conservations indicates that homologues play similar role in closely related organisms. UB05 antigen (XP_001347656.2) from Plasmodium falciparum is part of chimeric UB05-09 antigen; a potential vaccine candidate has been demonstrated to be a marker of protective immunity in malaria. The homologue of UB05 in Theileria parva is TpUB05 (XP_763711.1) which was also tested and shown to be a potential marker of protective immunity in ECF as well. In a bid to identify potent markers of protective immunity to aid...
Newcastle disease is a devastating viral disease of chicken in low- and middle-income countries w... more Newcastle disease is a devastating viral disease of chicken in low- and middle-income countries where the backyard production system is predominant. Marker-assisted selection of chickens that are resistant to Newcastle disease virus (NDV) is the promising strategy that needs to be explored. The aim of the present study was to investigate polymorphisms of the promoter region of the chicken Mx gene and association with Kuroiler, Sasso, and local Tanzanian chicken embryos’ survival variability to virulent NDV infection. Chicken embryos were initially challenged with a minimum lethal dose of virulent NDV suspension and then were followed over time to gather information on their survival variability. Using the survival data, high and less susceptible cohorts were established, and a total of 88 DNA samples from high and less susceptible groups were genotypes by sequencing. Five single-nucleotide polymorphisms (SNPs), which were previously reported, were detected. Interestingly, for the fi...
James Nyagwange 1, 3, Nicola Ternette 2, Edwin Tijhaar 3, Roger Pelle’ 4, Vish Nene 5 1, 4, 5 Int... more James Nyagwange 1, 3, Nicola Ternette 2, Edwin Tijhaar 3, Roger Pelle’ 4, Vish Nene 5 1, 4, 5 International Livestock Research Institute, P. O. Box 30709, Nairobi, Kenya 2 The Jenner Institute, Nuffield Department of Medicine, University of Oxford, UK 3 Cell Biology and Immunology Group, Wageningen University, The Netherlands Introduction East Coast fever (ECF) is a lymphoproliferative disease caused by the protozoan parasite Theileria parva. It kills about one million cattle annually in Africa. The sporozoite stage of this parasite, harbored in the salivary glands of the tick Rhipicephalus appendiculatus, invades and establishes infection in the bovine lymphocytes during tick feeding. However, little is known about the parasite molecules involved in this infection process. It is therefore necessary to elucidate the protein composition of the sporozoites to identify novel targets for blocking invasion. Blocking this initial stage of invasion presents a promising vaccine strategy for...
The parasiteTheileria parvais the causative agent of East Coast fever (ECF), one of the most seri... more The parasiteTheileria parvais the causative agent of East Coast fever (ECF), one of the most serious cattle diseases in sub-Saharan Africa, and directly impacts smallholder farmers’ livelihoods. There is an efficient live-parasite vaccine, but issues with transmission of vaccine strains, need of a cold chain, and antibiotics limit its utilization. This has fostered research towards subunit vaccination. Cytotoxic T lymphocytes (CTL) are crucial in combating the infection by lysingT. parva-infected cells. Tp1 is an immunodominant CTL antigen, which induces Tp1-specific responses in 70–80% of cattle of the A18 or A18v haplotype during vaccination with the live vaccine. In this study, human adenovirus serotype 5 (HAd5) and modified vaccinia Ankara (MVA) were assessed for their ability to induce Tp1-specific immunity. Both viral vectors expressing the Tp1 antigen were inoculated in cattle by a heterologous prime-boost vaccination regimen. All 15 animals responded to Tp1 as determined by ...
The extent of sequence diversity among the genes encoding 10 antigens (Tp1–10) known to be recogn... more The extent of sequence diversity among the genes encoding 10 antigens (Tp1–10) known to be recognized by CD8+T lymphocytes from cattle immune toTheileria parvawas analysed. The sequences were derived from parasites in 23 buffalo-derived cell lines, three cattle-derived isolates and one cloned cell line obtained from a buffalo-derived stabilate. The results revealed substantial variation among the antigens through sequence diversity. The greatest nucleotide and amino acid diversity were observed in Tp1, Tp2 and Tp9. Tp5 and Tp7 showed the least amount of allelic diversity, and Tp5, Tp6 and Tp7 had the lowest levels of protein diversity. Tp6 was the most conserved protein; only a single non-synonymous substitution was found in all obtained sequences. The ratio of non-synonymous: synonymous substitutions varied from 0.84 (Tp1) to 0.04 (Tp6). Apart from Tp2 and Tp9, we observed no variation in the other defined CD8+ T cell epitopes (Tp4, 5, 7 and 8), indicating that epitope variation is...
International journal for parasitology, Jul 11, 2016
An infection and treatment protocol is used to vaccinate cattle against Theileria parva infection... more An infection and treatment protocol is used to vaccinate cattle against Theileria parva infection. Due to incomplete cross-protection between different parasite isolates, a mixture of three isolates, termed the Muguga cocktail, is used for vaccination. While vaccination of cattle in some regions provides high levels of protection, some animals are not protected against challenge with buffalo-derived T. parva. Knowledge of the genetic composition of the Muguga cocktail vaccine is required to understand how vaccination is able to protect against field challenge and to identify the potential limitations of the vaccine. The aim of the current study was to determine the extent of genetic and antigenic diversity within the parasite isolates that constitute the Muguga cocktail. High throughput multi-locus sequencing of antigen-encoding loci was performed in parallel with typing using a panel of micro- and mini-satellite loci. The former focused on genes encoding CD8(+) T cell antigens, bel...
Polymorphism of immunodominant CD8+ T cell epitopes can facilitate escape from immune recognition... more Polymorphism of immunodominant CD8+ T cell epitopes can facilitate escape from immune recognition of pathogens, leading to strain-specific immunity. In this study, we examined the TCR β-chain (TRB) diversity of the CD8+ T cell responses of cattle against two immunodominant epitopes from Theileria parva (Tp1214–224 and Tp249–59) and investigated the role of TCR recognition and MHC binding in determining differential recognition of a series of natural variants of the highly polymorphic Tp249–59 epitope by CD8+ T cell clones of defined TRB genotype. Our results show that both Tp1214–224 and Tp249–59 elicited CD8+ T cell responses using diverse TRB repertoires that showed a high level of stability following repeated pathogenic challenge over a 3-y period. Analysis of single-alanine substituted versions of the Tp249–59 peptide demonstrated that Tp249–59-specific clonotypes had a broad range of fine specificities for the epitope. Despite this diversity, all natural variants exhibited part...
ABSTRACTImmunity against the bovine intracellular protozoan parasiteTheileria parvahas been shown... more ABSTRACTImmunity against the bovine intracellular protozoan parasiteTheileria parvahas been shown to be mediated by CD8 T cells. Six antigens targeted by CD8 T cells fromT. parva-immune cattle of different major histocompatibility complex (MHC) genotypes have been identified, raising the prospect of developing a subunit vaccine. To facilitate further dissection of the specificity of protective CD8 T-cell responses and to assist in the assessment of responses to vaccination, we set out to identify the epitopes recognized in theseT. parvaantigens and their MHC restriction elements. Nine epitopes in sixT. parvaantigens, together with their respective MHC restriction elements, were successfully identified. Five of the cytotoxic-T-lymphocyte epitopes were found to be restricted by products of previously described alleles, and four were restricted by four novel restriction elements. Analyses of CD8 T-cell responses to five of the epitopes in groups of cattle carrying the defined restricti...
Proceedings of the National Academy of Sciences, 2006
East Coast fever, caused by the tick-borne intracellular apicomplexan parasiteTheileria parva, is... more East Coast fever, caused by the tick-borne intracellular apicomplexan parasiteTheileria parva, is a highly fatal lymphoproliferative disease of cattle. The pathogenic schizont-induced lymphocyte transformation is a unique cancer-like condition that is reversible with parasite removal. Schizont-infected cell-directed CD8+cytotoxic T lymphocytes (CTL) constitute the dominant protective bovine immune response after a single exposure to infection. However, the schizont antigens targeted byT. parva-specific CTL are undefined. Here we show the identification of five candidate vaccine antigens that are the targets of MHC class I-restricted CD8+CTL from immune cattle. CD8+T cell responses to these antigens were boosted inT. parva-immune cattle resolving a challenge infection and, when used to immunize naïve cattle, induced CTL responses that significantly correlated with survival from a lethal parasite challenge. These data provide a basis for developing a CTL-targeted anti-East Coast fever...
Background: African swine fever (ASF) is a lethal hemorrhagic disease affecting domestic pigs res... more Background: African swine fever (ASF) is a lethal hemorrhagic disease affecting domestic pigs resulting in up to 100 % mortality rates caused by the ASF virus (ASFV). The locally-adapted pigs in South-western Kenya have been reported to be resilient to disease and harsh climatic conditions and tolerate ASF; however, the mechanisms by which this tolerance is sustained remain largely unknown. We evaluated the gene expression patterns in spleen tissues of these locally-adapted pigs in response to varying infective doses of ASFV to elucidate the virus-host interaction dynamics. Methods: Locally adapted pigs (n=14) were experimentally infected with a high dose (1x106HAD50), medium dose (1x104HAD50), and low dose (1x102HAD50) of the highly virulent genotype IX ASFV Ken12/busia.1 (Ken-1033) isolate diluted in PBS and followed through the course of infection for 29 days. The in vivo pig host and ASFV pathogen gene expression in spleen tissues from 10 pigs (including three from each infectiv...
Swine leukocyte antigen (SLA) plays a central role in controlling the immune response by discrimi... more Swine leukocyte antigen (SLA) plays a central role in controlling the immune response by discriminating self and foreign antigens and initiating an immune response. Studies on SLA polymorphism have demonstrated associations between SLA allelic variants, immune response, and disease resistance. The SLA polymorphism is due to host-pathogen co-evolution resulting in improved adaptation to diverse environments making SLA a crucial genomic region for comparative diversity studies. Although locally-adapted African pigs have small body sizes, they possess increased resilience under harsh environmental conditions and robust immune systems with reported tolerance to some diseases, including African swine fever. However, data on the SLA diversity in these pigs are not available. We characterized the SLA of unrelated locally-adapted domestic pigs from Homa Bay, Kenya, alongside exotic pigs and warthogs. We undertook SLA comparative diversity of the functionally expressed SLA class I (SLA-1, SL...
Background African swine fever (ASF), a highly contagious hemorrhagic disease, affects domestic p... more Background African swine fever (ASF), a highly contagious hemorrhagic disease, affects domestic pigs in the Democratic Republic of Congo (DRC) where regular outbreaks are reported leading to high mortality rates approaching 100% in the affected regions. No study on the characteristics of the complete genome of strains responsible for ASF outbreaks in the South Kivu province of DRC is available, limited a better understanding of molecular evolution and spread of this virus within the country. The present study aimed at determining the complete genome sequence of ASFV strains genotype X involved in 2018–2019 ASF disease outbreaks in South Kivu province of DRC. Materials and methods Genomic DNA of a spleen sample from an ASFV genotype X-positive domestic pig in Uvira, during the 2018–2019 outbreaks in South Kivu, was sequenced using the Illumina HiSeq X platform. Obtained trimmed reads using Geneious Prime 2020.0.4 were blasted against a pig reference genome then contigs were generated...
Theileria parva is an economically important, intracellular, tick-transmitted parasite of cattle.... more Theileria parva is an economically important, intracellular, tick-transmitted parasite of cattle. A live vaccine against the parasite is effective against challenge from cattle-transmissible T. parva but not against genotypes originating from the African Cape buffalo, a major wildlife reservoir, prompting the need to characterize genome-wide variation within and between cattle- and buffalo-associated T. parva populations. Here, we describe a capture-based target enrichment approach that enables, for the first time, de novo assembly of nearly complete T. parva genomes derived from infected host cell lines. This approach has exceptionally high specificity and sensitivity and is successful for both cattle- and buffalo-derived T. parva parasites. De novo genome assemblies generated for cattle genotypes differ from the reference by ∼54K single nucleotide polymorphisms (SNPs) throughout the 8.31 Mb genome, an average of 6.5 SNPs/kb. We report the first buffalo-derived T. parva genome, whi...
Astroviruses (AstVs) are widely distributed and are associated with gastroenteritis in human and ... more Astroviruses (AstVs) are widely distributed and are associated with gastroenteritis in human and animals. The knowledge of the genetic diversity and epidemiology of AstVs in Africa is limited. This study aimed to characterize astroviruses in asymptomatic smallholder piglets in Kenya and Uganda. Twenty-four samples were randomly selected from a total of 446 piglets aged below 6 months that were initially collected for rotavirus study and sequenced for whole genome analysis. Thirteen (13/24) samples had contigs with high identity to genus Mamastrovirus. Analysis of seven strains with complete (or near complete) AstV genome revealed variable nucleotide and amino acid sequence identities with known porcine astrovirus (PoAstV) strains. The U083 and K321 strains had nucleotide sequence identities ranging from 66.4 to 75.4% with the known PoAstV2 strains; U460 strain had nucleotide sequence identities of 57.0 to 65.1% regarding the known PoAstV3; and K062, K366, K451, and K456 strains had ...
Background African swine fever (ASF) is a highly contagious and severe hemorrhagic viral disease ... more Background African swine fever (ASF) is a highly contagious and severe hemorrhagic viral disease of domestic pigs. The analysis of variable regions of African swine fever virus (ASFV) genome led to more genotypic and serotypic information about circulating isolates. The present study aimed at investigating the genetic diversity of ASFV strains in symptomatic pigs in South Kivu province of the Democratic Republic of Congo (DRC). Materials and Methods Blood samples collected from 391 ASF symptomatic domestic pigs in 6 of 8 districts in South Kivu were screened for the presence of ASFV, using a VP73 gene-specific polymerase chain reaction (PCR) with the universal primer set PPA1-PPA2. To genotype the isolates, we sequenced and compared the nucleotide sequences of PPA-positive samples at three loci: the C-terminus of B646L gene encoding the p72 protein, the E183L gene encoding the p54 protein, and the central hypervariable region (CVR) of the B602L gene encoding the J9L protein. In addi...
Despite the amount of resources deployed and technological advancements in Molecular Biology, vac... more Despite the amount of resources deployed and technological advancements in Molecular Biology, vaccinology, immunology, genetics, and biotechnology, there is still no effective vaccines against malaria. Immunity to either malaria or East Coast fever is usually seen as species- and/or strain-specific. But there is growing body of evidence suggesting the possibility of the existence of cross strain, cross species and cross genus immune responses in apicomplexans. The principle of gene conservations indicates that homologues play similar role in closely related organisms. UB05 antigen (XP_001347656.2) from Plasmodium falciparum is part of chimeric UB05-09 antigen; a potential vaccine candidate has been demonstrated to be a marker of protective immunity in malaria. The homologue of UB05 in Theileria parva is TpUB05 (XP_763711.1) which was also tested and shown to be a potential marker of protective immunity in ECF as well. In a bid to identify potent markers of protective immunity to aid...
Newcastle disease is a devastating viral disease of chicken in low- and middle-income countries w... more Newcastle disease is a devastating viral disease of chicken in low- and middle-income countries where the backyard production system is predominant. Marker-assisted selection of chickens that are resistant to Newcastle disease virus (NDV) is the promising strategy that needs to be explored. The aim of the present study was to investigate polymorphisms of the promoter region of the chicken Mx gene and association with Kuroiler, Sasso, and local Tanzanian chicken embryos’ survival variability to virulent NDV infection. Chicken embryos were initially challenged with a minimum lethal dose of virulent NDV suspension and then were followed over time to gather information on their survival variability. Using the survival data, high and less susceptible cohorts were established, and a total of 88 DNA samples from high and less susceptible groups were genotypes by sequencing. Five single-nucleotide polymorphisms (SNPs), which were previously reported, were detected. Interestingly, for the fi...
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