Browsing by Author "Njahira, Moses"

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    Antigen gene and variable number tandem repeat (VNTR) diversity in Theileria parva parasites from Ankole cattle in south‐western Uganda: Evidence for conservation in antigen gene sequences combined with extensive polymorphism at VNTR loci
    (Transboundary and emerging diseases, 2020) Nanteza, Anne; Obara, Isaiah; Kasaija, Paul; Mwega, Elisa; Kabi, Fredrick; Salih, Diaeldin A.; Njahira, Moses; Njuguna, Joyce; Odongo, David; Bishop, Richard P.; Skilton, Rob A.; Ahmed, Jabbar; Clausen, Peter‐Henning; Lubega, George W.
    Theileria parva is a tick‐transmitted apicomplexan protozoan parasite that infects lymphocytes of cattle and African Cape buffalo (Syncerus caffer), causing a frequently fatal disease of cattle in eastern, central and southern Africa. A live vaccination procedure, known as infection and treatment method (ITM), the most frequently used version of which comprises the Muguga, Serengeti‐transformed and Kiambu 5 stocks of T. parva, delivered as a trivalent cocktail, is generally effective. However, it does not always induce 100% protection against heterologous parasite challenge. Knowledge of the genetic diversity of T. parva in target cattle populations is therefore important prior to extensive vaccine deployment. This study investigated the extent of genetic diversity within T. parva field isolates derived from Ankole (Bos taurus) cattle in south‐western Uganda using 14 variable number tandem repeat (VNTR) satellite loci and the sequences of two antigen‐encoding genes that are targets of CD8+T‐cell responses induced by ITM, designated Tp1 and Tp2. The findings revealed a T. parva prevalence of 51% confirming endemicity of the parasite in south‐western Uganda. Cattle‐derived T. parva VNTR genotypes revealed a high degree of polymorphism. However, all of the T. parva Tp1 and Tp2 alleles identified in this study have been reported previously, indicating that they are widespread geographically in East Africa and highly conserved.
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    Apparent density, trypanosome infection rates and host preference of tsetse flies in the sleeping sickness endemic focus of northwestern Uganda
    (BMC Veterinary Research, 2021) Opiro, Robert; Opoke, Robert; Angwech, Harriet; Nakafu, Esther; Oloya, Francis A.; Openy, Geoffrey; Njahira, Moses; Macharia, Mercy; Echodu, Richard; Malinga, Geoffrey M.
    African trypanosomiasis, caused by protozoa of the genus Trypanosoma and transmitted by the tsetse fly, is a serious parasitic disease of humans and animals. Reliable data on the vector distribution, feeding preference and the trypanosome species they carry is pertinent to planning sustainable control strategies. Methodology: We deployed 109 biconical traps in 10 villages in two districts of northwestern Uganda to obtain information on the apparent density, trypanosome infection status and blood meal sources of tsetse flies. A subset (272) of the collected samples was analyzed for detection of trypanosomes species and sub-species using a nested PCR protocol based on primers amplifying the Internal Transcribed Spacer (ITS) region of ribosomal DNA. 34 blood-engorged adult tsetse midguts were analyzed for blood meal sources by sequencing of the mitochondrial cytochrome c oxidase 1 (COI) and cytochrome b (cytb) genes. Results: We captured a total of 622 Glossina fuscipes fuscipes tsetse flies (269 males and 353 females) in the two districts with apparent density (AD) ranging from 0.6 to 3.7 flies/trap/day (FTD). 10.7% (29/272) of the flies were infected with one or more trypanosome species. Infection rate was not significantly associated with district of origin (Generalized linear model (GLM), χ2 = 0.018, P = 0.895, df = 1, n = 272) and sex of the fly (χ2 = 1.723, P = 0.189, df = 1, n = 272). However, trypanosome infection was highly significantly associated with the fly’s age based on wing fray category (χ2 = 22.374, P < 0.001, df = 1, n = 272), being higher among the very old than the young tsetse. Nested PCR revealed several species of trypanosomes: T. vivax (6.62%), T. congolense (2.57%), T. brucei and T. simiae each at 0.73%. Blood meal analyses revealed five principal vertebrate hosts, namely, cattle (Bos taurus), humans (Homo sapiens), Nile monitor lizard (Varanus niloticus), African mud turtle (Pelusios chapini) and the African Savanna elephant (Loxodonta africana). Conclusion: We found an infection rate of 10.8% in the tsetse sampled, with all infections attributed to trypanosome species that are causative agents for AAT. However, more verification of this finding using large-scale passive and active screening of human and tsetse samples should be done. Cattle and humans appear to be the most important tsetse hosts in the region and should be considered in the design of control interventions.
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    Genetic Diversity in Napier Grass (Pennisetum purpureum) Assessed by SSR Markers
    (Journal of Agricultural Science, 2015) Kawube, Geofrey; Alicai, Titus; Wanjala, Bramwel; Njahira, Moses; Awalla, Juma; Skilton, Robert
    Understanding of genetic diversity among Napier grass is very important for selection and improvement of Napier grass breeding population. This study determined the genetic diversity among the farmer preferred, wild (local) and selected ILRI gene-bank Napier grass clones using 23 SSR markers selected from pearl millet, maize and sorghum. The results indicated polymorphism among the SSR markers, revealing a total of 339 alleles of which 27.1% alleles were unique, occurring either only in local, farmers preferred or ILRI clones. Similarly, genetic diversity and observed heterozygosity were highest in the local than in farmers’ preferred and least in the ILRI gene-bank clones. The clones clustered in two groups with a few overlaps, although most of the farmer’s grown Napier grass clones grouped with those from ILRI genebank and clone P99, emphasizing their genetic relatedness. Therefore, the unique alleles revealed in the local clones may be associated with adaptability to local environments. These alleles could, therefore, be exploited for genetic improvement of the farmer preferred Napier grass.