Browsing by Author "Tonny Kabuuka"

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African Swine Fever Diagnosis in Africa: Challenges and Opportunities
(Pathogens, 2024-04-02) Mary-Louise Penrith; Juanita van Emmenes; Jean N. Hakizimana; Livio Heath; Tonny Kabuuka; Gerald Misinzo; Theophilus Odoom; Abel Wade; Habibata L. Zerbo; Pam D. Luka
The global spread of African swine fever (ASF) in recent decades has led to the need for technological advances in sampling and diagnostic techniques. The impetus for these has been the need to enable sampling by lay persons and to obtain at least a preliminary diagnosis in the eld for early control measures to be put in place before final laboratory confirmation. In rural Africa, rapid diagnosis is hampered by challenges that include lack of infrastructure as well as human and financial resources. Lack of animal health personnel, access to affordable means to transport eld samples to a laboratory, and lack of laboratories with the capacity to make the diagnosis result in severe under-reporting of ASF, especially in endemic areas. This review summarizes the challenges identified in gap analyses relevant to low- and middle-income countries, with a focus on Africa, and explore the opportunities provided by recent research to improve eld diagnosis and quality of diagnostic samples used. Sampling techniques include invasive sampling techniques requiring trained personnel and non-invasive sampling requiring minimal training, sampling of decomposed carcass material, and preservation of samples in situations where cold chain maintenance cannot be guaranteed. Availability and efficacy of point-of-care (POC) tests for ASF has improved considerably in recent years and their application, as well as advantages and limitations, are discussed. The adequacy of existing laboratory diagnostic capacity is evaluated and opportunities for networking amongst reference and other laboratories offering diagnostic services are discussed. Maintaining laboratory diagnostic efficiency in the absence of samples during periods of quiescence is another issue that requires attention, and the role of improved laboratory networking is emphasized. Early diagnosis of ASF is key to managing the disease spread. Therefore, the establishment of the Africa Chapter of the Global African Swine Fever Research Alliance (GARA) increases opportunities for collaboration and networking among the veterinary diagnostic laboratories in the region.
Identification of a New Domestic Pig Cell Line for Growth of African Swine Fever Viruses for Vaccine Production in Uganda
(National Agricultural Research Organisation, 2024-05-17) Samuel Mulondo; Richard Ezinga; Daisy Iwutung; Richard M Kabaka; Moses Tefula Dhikusooka; Swidiq Mugerwa; Tonny Kabuuka
In this study, a basis for the feasibility of a successful ASF vaccine design program using live attenuated vaccines was sought. One of the challenges to African swine fever (ASF) vaccine development is having a cell line that will provide commercial utility for vaccine production. We set out to address this problem by innovatively identifying possible cell lines from local domestic pigs in the country. Eight tissue types from ASF-negative animals were identified for incorporation into cell line development. These were degraded, incubated, and monitored for cell growth. One cell line, the SIR2-P, grew consistently and confluently and was tested for the ability to grow and isolate field ASF viruses. We report the isolation of ASF viruses in our laboratory for the first time. The P9C virus from Namayingo district exhibited the largest plaque sizes compared to the SQ517B virus from Mukono. The innovative identification of the SIR2-P cell line is proof of concept that newer species- specific cell lines can be developed in the Infectious Animal Disease Laboratory (IADL), and utilized to study other animal viruses like Porcine Reproductive and Respiratory Syndrome (PRRS) virus, Foot and mouth disease (FMD) virus, and Swine Influenza. Such cells can be used in vaccine production for other endemic diseases in Uganda. The SIR2-P cell line is currently at passage 65.
Retrospective Multi-Locus Sequence Analysis of African Swine Fever Viruses by “PACT” Confirms Co-Circulation of Multiple Outbreak Strains in Uganda
(Animals, 2023-12-24) Tonny Kabuuka; Henry Mulindwa; Armanda D. S. Bastos; Juanita van Heerden; Livio Heath; Folorunso O. Fasina
African swine fever (ASF) is a haemorrhagic fever of swine that severely constrains pig production, globally. In Uganda, at least 388 outbreaks of ASF were documented from 2001 to 2012. We undertook a retrospective serological and molecular survey of ASF virus (ASFV) using banked samples collected from seven districts (Pallisa, Lira, Abim, Nebbi, Kabarole, Kibaale, and Mukono) of Uganda. Six assays (ELISA for antibody detection, diagnostic p72 gene PCR and genomic ampli cation, and sequencing of four gene regions (p72 [P], p54 [A], CVR of the 9RL-ORF [C], and TK [T]), hereinafter referred to as P-A-C-T (PACT)) were evaluated. Antibodies to ASFV were detected in the Abim district (6/25; 24.0%), and the remainder of the serum samples were negative (187/193; 96.9%). For the tissue samples, ASFV detection by assay was 8.47% for P, 6.78% for A, 8.47% for C, and 16.95% for T. The diagnostic PCR (p72 gene) detected seven positive animals from four districts, whereas the TK assay detected ten positives from all seven districts. In addition to the superior detection capability of TK, two virus variants were discernible, whereas CVR recovered three variants, and p72 and p54 sequencing each identi ed a single variant belonging to genotype IX. Our results indicate that dependence on serology alone underestimates ASF positivity in any infected region, that multi-locus sequence analysis provides better estimates of outbreak strain diversity, and that the TK assay is superior to the WOAH-prescribed conventional p72 diagnostic PCR, and warrants further investigation.