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The introduction of alien species may pose an enormous threat to indigenous flora and fauna. Among introduced animals, probably the most destructive to the natural environment are mammals. This is true at least in regard to the Afrotropical Region (sub-Saharan Africa). This review attempts to summarize our knowledge on alien mammals in this region and their impact on indigenous vertebrate fauna. This review includes 56 mammal species, belonging to 20 families, introduced to sub-Saharan Africa over the last 2000 years. Most are representatives of the following orders: Artiodactyla, Carnivora, and Primates. Most species introduced to sub-Saharan Africa originated from the Oriental (n = 20) and Palearctic (n = 19) regions. Two species, Mus musculus and Rattus rattus, were introduced before 1400 (probably as early as 800 AD), while three others were introduced between 1401 and 1700. The first half of the 17th century saw the highest number (n = 10) of introduced species. Between 1651 and 1850, only two species were introduced; in the following 175 years (1851–2025), as many as 24 species were introduced. Ten of the introduced mammal species, namely Sus scrofa, Capra hircus, Rattus rattus, R. norvegicus, Mus musculus, Felis catus, Canis familiaris, Viverricula indica, Urva auropunctata, and Maccaca fuscicularis, have become invasive species. A total of 39 mammal species were relocated (mainly for hunting purposes) within sub-Saharan Africa. Most of them were representatives of the family Bovidae (76.9%). Relocations are not considered introductions. Based on published records of the impacts of alien mammals on the vertebrate fauna of sub-Saharan Africa, the following mechanisms may be distinguished: predation, competition, hybridization, transmission of diseases and parasites, and habitat destruction (grazing, herbivory, browsing). Most vertebrate species (79.4%) were affected through direct predation, predation and habitat destruction (7.1%), or predation and competition (1.4%). Alien mammals have caused habitat destruction for only 10 species (7.1%). Other effects (competition and genetic pollution) were marginal (3.5%). At least 144 vertebrate species, representing 52 families, have been affected by alien mammals in sub-Saharan Africa: 3 amphibians, 23 reptiles, 89 birds, and 29 mammals. As a result of mammal introductions, 65 species in sub-Saharan Africa have become globally extinct, 45 are considered threatened (listed in the RDB), and 31 other species are in decline, although not included in the RDB. Most extinct birds were affected by introduced rats, mice, feral cats, and dogs. In continental Africa, only seven vertebrate species have been negatively affected by alien mammals. All other affected vertebrates occur on islands. An especially high rate of extinction has been recorded in the Mascarene Islands. In comparison with alien birds in sub-Saharan Africa, the number of introduced mammal species is much lower, but their negative impact on vertebrate fauna is significantly greater. Full article

Laboratory mice are instrumental for preclinical research but there are serious concerns that the use of a clean standardized environment for specific-pathogen-free (SPF) mice results in poor bench-to-bedside translation due to their immature immune system. The aim of the present study was to test the importance of the gut microbiota in wild vs. SPF mice for evaluating host immune responses in a house-dust-mite-induced allergic airway inflammation model without the influence of pathogens. The wild mouse microbiome reduced histopathological changes and TNF-α in the lungs and serum when transplanted to microbiota-depleted mice compared to mice transplanted with the microbiome from SPF mice. Moreover, the colonic gene expression of Gata3 was significantly lower in the wild microbiome-associated mice, whereas Muc1 was more highly expressed in both the ileum and colon. Intestinal microbiome and metabolomic analyses revealed distinct profiles associated with the wild-derived microbiome. The wild-mouse microbiome thus partly reduced sensitivity to house-dust-mite-induced allergic airway inflammation compared to the SPF mouse microbiome, and preclinical studies using this model should consider using both ‘dirty’ rewilded and SPF mice for testing new therapeutic compounds due to the significant effects of their respective microbiomes and derived metabolites on host immune responses. Full article

For many decades, the betaretrovirus, mouse mammary tumour virus (MMTV), has been a causal suspect for human breast cancer. In recent years, substantial new evidence has been developed. Based on this evidence, we hypothesise that MMTV has a causal role. We have used an extended version of the classic A. Bradford Hill causal criteria to assess the evidence. 1. Identification of MMTV in human breast cancers: The MMTV 9.9 kb genome in breast cancer cells has been identified. The MMTV genome in human breast cancer is up to 98% identical to MMTV in mice. 2. Epidemiology: The prevalence of MMTV positive human breast cancer is about 35 to 40% of breast cancers in Western countries and 15 to 20% in China and Japan. 3. Strength of the association between MMTV and human breast cancer: Consistency—MMTV env gene sequences are consistently five-fold higher in human breast cancer as compared to benign and normal breast controls. 4. Temporality (timing) of the association: MMTV has been identified in benign and normal breast tissues up to 10 years before the development of MMTV positive breast cancer in the same patient. 5. Exposure: Exposure of humans to MMTV leads to development of MMTV positive human breast cancer. 6. Experimental evidence: MMTVs can infect human breast cells in culture; MMTV proteins are capable of malignantly transforming normal human breast epithelial cells; MMTV is a likely cause of biliary cirrhosis, which suggests a link between MMTV and the disease in humans. 7. Coherence—analogy: The life cycle and biology of MMTV in humans is almost the same as in experimental and feral mice. 8. MMTV Transmission: MMTV has been identified in human sputum and human milk. Cereals contaminated with mouse fecal material may transmit MMTV. These are potential means of transmission. 9. Biological plausibility: Retroviruses are the established cause of human cancers. Human T cell leukaemia virus type I (HTLV-1) causes adult T cell leukaemia, and human immunodeficiency virus infection (HIV) is associated with lymphoma and Kaposi sarcoma. 10. Oncogenic mechanisms: MMTV oncogenesis in humans probably differs from mice and may involve the enzyme APOBEC3B. Conclusion: In our view, the evidence is compelling that MMTV has a probable causal role in a subset of approximately 40% of human breast cancers. Full article

Cryptosporidium spp., common parasites of vertebrates, remain poorly studied in wildlife. This study describes the novel Cryptosporidium species adapted to nutrias (Myocastor coypus). A total of 150 faecal samples of feral nutria were collected from locations in the Czech Republic and Slovakia and examined for Cryptosporidium spp. oocysts and specific DNA at the SSU, actin, HSP70, and gp60 loci. Molecular analyses revealed the presence of C. parvum (n = 1), C. ubiquitum subtype family XIId (n = 5) and Cryptosporidium myocastoris n. sp. XXIIa (n = 2), and XXIIb (n = 3). Only nutrias positive for C. myocastoris shed microscopically detectable oocysts, which measured 4.8–5.2 × 4.7–5.0 µm, and oocysts were infectious for experimentally infected nutrias with a prepatent period of 5–6 days, although not for mice, gerbils, or chickens. The infection was localised in jejunum and ileum without observable macroscopic changes. The microvilli adjacent to attached stages responded by elongating. Clinical signs were not observed in naturally or experimentally infected nutrias. Phylogenetic analyses at SSU, actin, and HSP70 loci demonstrated that C. myocastoris n. sp. is distinct from other valid Cryptosporidium species. Full article