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Tissue-specific and sex-dependent microbiome structure in East African cattle ticks (Amblyomma gemma and Rhipicephalus pulchellus) and their bovine hosts
Getange, Dennis; Mukaratirwa, Samson; Khogali, Rua Khogali Ibrahim; Yuko, Epaphrus; Kabii, James; Bargul, Joel L.; Villinger, Jandouwe (Elsevier, 2026-08)
Ticks and their vertebrate hosts share intimate ecological interactions that shape microbial community composition, with implications for tick fitness and pathogen transmission. However, the extent and specificity of tick–host microbial interactions remain poorly understood, particularly in East African tick species. Here, we characterised microbial communities across multiple tissue types from two economically important tick species (Amblyomma gemma and Rhipicephalus pulchellus) and their shared bovine host using 16S rRNA V1-V2 gene sequencing. We profiled haemolymph, midgut, salivary glands, and gonads from individual ticks (25 Am. gemma and 8 Rh. pulchellus), alongside 12 bovine blood samples. Microbiota were dominated by Proteobacteria, Firmicutes, Actinobacteriota, and Bacteroidota, with Coxiella, Rickettsia, and Acinetobacter as the most abundant genera. Despite substantial taxonomic overlap, Am. gemma harboured more unique bacterial genera than Rh. pulchellus, suggesting species-specific microbial associations. Alpha and beta diversity analyses indicated distinct community structures between tick species and host blood. Tissue-level analyses revealed striking sexual dimorphism in both species: males exhibited stable microbial communities across tissues, whereas females showed strong tissue-dependent variation in richness, diversity, and composition. Co-occurrence network analyses, restricted to Am. gemma due to limited Rh. pulchellus sample size, identified sex- and tissue-specific putative keystone taxa, including Georgenia in male midguts, Serratia in female salivary glands, Enhydrobacter in ovaries, and Gemmatimonas in testes, suggesting roles in community stability. These findings highlight tissue-specific and sex-dependent factors as key determinants of tick microbial community composition, with implications for pathogen maintenance and transmission in East African livestock systems. HIGHLIGHTS • Tissue-specific 16S profiles reveal distinct microbiomes across tick organs. • Female ticks show stronger tissue effects; males vary less across tissues. • Coxiella dominates ovaries; Rickettsia africae is enriched in salivary glands. • Co-occurrence networks reveal sex- and tissue-specific putative keystone taxa. • Tick microbiomes differ from host blood despite partial taxonomic overlap.
The need for a One Health approach in humanitarian aid : the role of veterinarians and animal health professionals
Scagliarini, Alessandra; Durrheim, David N.; Green, Sarah; Blumberg, Lucille Hellen (Elsevier, 2026-09)
No abstract available.
Tick bite fever in southern Africa
Frean, John; Nel, Jeremy; Blumberg, Lucille Hellen; Taljaard, Jantjie (Elsevier, 2026-06)
Tick bite fever (TBF) is a well-known zoonotic disease in southern Africa, caused by ixodid tick-transmitted rickettsial pathogens of the spotted fever group, which target endothelial cells, producing widespread vasculitis. Two epidemiologic and clinical forms of the condition can be distinguished, namely, African TBF and Mediterranean spotted fever–like infection. TBF is generally a mild illness, but delayed diagnosis and inappropriate treatment may lead to severe, potentially fatal, disease resembling bacterial sepsis, viral hemorrhagic fever, malaria, or other serious infections. Along with compatible epidemiologic history, common clinical diagnostic features at initial presentation are fever, headache, rash, myalgia and eschar; tender regional lymphadenopathy is common. Clinical diagnosis is sufficient to warrant treatment because serological response is slow to develop; although polymerase chain reaction of eschar material is an additional or alternative diagnostic option, this method may not be readily available. The treatment of choice is doxycycline, with macrolides as second-line antibiotics. Personal prevention revolves around awareness of risks and measures to limit exposure to ticks. As a zoonosis with a wide range of reservoir hosts, the disease cannot be eliminated but risk can be reduced by application of One Health principles. HIGHLIGHTS • Tick bite fever (TBF) is a common regional tick-transmitted rickettsial infection. • Two forms: Mediterranean spotted fever (MSF)–like and African tick bite fever (ATBF). • MSF and ATBF differ in pathogen and vector species, epidemiology, and severity. • Severe TBF can resemble other bacterial sepsis or viral hemorrhagic fever. • The antibiotic of first choice is doxycycline in most patients; alternatively, macrolides.
Cladosporium from caves of the Brazilian savannah (Cerrado) and the description of six new species
Felix-Oliveira, Pedro H.; Prazeres, Jose F.S.A.; Ferro, Layanne O.; Antunes, Ana C.A.; Lima, Caroline F.; Neves, Dominnyke S.S.; Fonseca, Emily O.; Miranda, Lorena S.; Momoli, Renata S.; Souza-Motta, Cristina M.; Bensch, Konstanze; Crous, Pedro W.; Bezerra, Jadson D.P. (Pensoft Publishers, 2026-06-03)
Caves are important but understudied reservoirs of fungal diversity, particularly for genera such as Cladosporium (Cladosporiales, Dothideomycetes). This study aimed to characterise the richness of Cladosporium species from six caves in the Brazilian savannah (Cerrado) using an integrative approach combining morphology and multi-locus phylogenetic analyses (ACT, ITS, RPB2, TEF1-α, and TUB). To improve species recognition in Cladosporium, selected ex-type strains were studied, for which RPB2 and TUB barcodes were also sequenced. Species were delimited using morphology and phylogenetic inferences, supplemented by the pairwise homoplasy index (PHI) test to evaluate species boundaries. Twenty-three species were identified among 94 Cladosporium isolates. The polyphasic approach resulted in the description of six new species: five in the C. cladosporioides complex (C. carsi, C. lacerdae, C. mambaiense, C. nogueirae, and C. propiciense) and one in the C. sphaerospermum complex (C. mesquitapaivae). Additionally, analyses based on morphology, genealogical concordance phylogenetic species recognition (GCPSR), and the PHI test resulted in the synonymisation of C. ribis and C. speluncae under C. bambusicola, C. brigadeirense under C. puris, and C. marinisedimentum under C. sphaerospermum. Among the previously known species identified, 11 represent new records for cave environments, with C. bambusicola being the most frequent (29.17%). These findings substantially expand the known diversity of Cladosporium in Neotropical caves, highlighting the Brazilian Cerrado as a hotspot of mycodiversity. Furthermore, ACT, RPB2, TEF1-α, and TUB are proposed as the primary phylogenetic barcodes for distinguishing closely related Cladosporium species, particularly within the C. cladosporioides complex. This study further emphasises the necessity of using a polyphasic approach to achieve accurate taxonomic resolution among Cladosporium species, trace their distribution in caves, and help to understand their ecology.
Characterisation of HIV-1 gag cytotoxic T-lymphocyte epitopes in the southern African region-a systematic review
Fortuin, Tumelo Leroy; Nkone, Paballo; Loubser, Shayne; Tiemessen, Caroline T.; Mayaphi, Simnikiwe Horatious (Wiley, 2026)
During early HIV-1 infection, robust Cytotoxic T-lymphocyte (CTL) responses are mostly targeted at immunodominant Gag p24 epitopes to reduce HIV-1 viraemia to a set-point. The aim of this study was to review the current body of knowledge on HIV-1 Gag CTL epitopes in the southern African region where subtype C is prevalent. Peer-reviewed records were obtained from three databases: PubMed Central, Web of Science Core Collection, and Scopus, using the following search terms: HIV subtype C Gag epitopes, and HIV clade C Gag epitopes. The search results were restricted to countries within the southern African region, and only data published in English and between the years 2000-2025 were considered for this review. The search from the three databases produced a total of 2103 peer-reviewed records, and 49 records were included in the review. The majority of studies (58.44%) were conducted in South Africa, followed by Botswana (15.58%), Zambia (10.39%), Malawi (7.79%), Zimbabwe (6.49%) and Angola (1.30%). There were no studies identified from other southern African countries. A total of 60 Gag CTL epitopes were identified, of which 17 (28.33%) were located within the matrix protein (p17), 33 (55.00%) within the capsid protein (p24), and 4 (6.67%) within the Gag polyprotein (p2p7p1p6). The commonly detected immunodominant epitopes were mostly located within the Gag p24 protein; and included TPQDLNTML (TL9, Gag p24 48-56) and TSTLQEQIGW (TW10, Gag p24 108-117) present at 16.00% and 13.3%, respectively. The proportion of HLA-A, B and C allotypes in this systematic review were 18%, 78%, and 4%, respectively. The more common HLA-B allotypes that restrict immunodominant Gag epitopes and facilitate better control of HIV-1 were HLA-B*57, -B*58:01, -B*42:01 and -B*81:01. This systematic review has provided important insights into the description of immunodominant Gag epitopes and HLA-I alleles that contribute to the control of HIV-1 viraemia in the southern African region. It has also exposed that some CTL epitopes identified in the southern African studies are not reported on the Los Alamos HIV database (LANL HIV database). This highlights a need to have this database updated with this information as it is used as a reference for epitopes. This review could provide insights into the design of an epitope-based HIV-1 vaccine that would also be effective in the southern African region.