Contagious bovine pleuropneumonia (CBPP) is a severe disease caused by Mycoplasma mycoides subsp. mycoides (Mmm). Knowledge on CBPP pathogenesis is fragmented and hampered by the limited availability of laboratory animal and in vitro models of investigation. The purpose of the present study is to assess respiratory explants as useful tools to study the early stages of CBPP. Explants were obtained from trachea, bronchi and lungs of slaughtered cattle, tested negative for Mycoplasma spp. and for the major bacterial and viral respiratory pathogens. The interaction of Mmm with explant cells was studied by immunohistochemistry (IHC), double-labelling indirect immunofluorescence (DLIIF) and laser scanning confocal microscopy (LSCM). Mmm capability to survive and proliferate within the explants was evaluated by standard microbiological procedures. Finally, the putative cellular internalization of Mmm was further investigated by the gentamicin invasion assay. IHC and DLIIF indicated that Mmm can colonize explants, showing a marked tropism for lower airways. Specifically, Mmm was detected on/inside the bronchiolar and alveolar epithelial cells, the alveolar macrophages and the endothelial cells. The interaction between Mmm and explant cells was abolished by the pre-incubation of the pathogen with bovine anti-Mmm immune sera. Mmm was able to survive and proliferate in all tracheal, bronchial and lung explants, during the entire time course of the experiments. LSCM and gentamicin invasion assay both confirmed that Mmm can enter non-phagocytic host cells. Taken together, our data supports bovine respiratory explants as a promising tool to investigate CBPP, alternative to cattle experimental infection.

African horse sickness (AHS) is a non-contagious, insect-borne disease of equids caused by a RNA virus (AHSV), which belongs to the genus Orbivirus, family Reoviridae. The disease is endemic in sub-Saharan and western Africa, where prevention strictly depends upon vaccination. The present paper aims at evaluating the serological response and the occurrence of AHS in horses bred under field condition and regularly immunized using the commercially available live attenuated vaccine (LAV) produced by Onderstepoort Biological Products.The study was carried out in a farm located in the district of Windhoek (Namibia), where the disease is endemic. A total of 72 cross-breed horses, out of the 150 housed on the farm, were subdivided in six age groups, from 2 to 7years-old. Each group consisted of 12 heads which were born during the same breeding season and had undergone from four to nine vaccination courses. AHSV specific immune response was evaluated by serum-virus neutralization test. Data about the clinical occurrence of the AHS from 2006 to 2011 were made available. The immune response, in terms of number of seropositive horses and serum neutralizing titers, was quite variable among horses and against different serotypes. Neutralizing antibodies against all serotypes were recorded in all the horses only after eight vaccination courses at 6years of age onwards. Immune response to AHSV-5 and 9, which are not included in the LAV formulation, were also established. A severe AHS epidemic occurred in Namibia in 2011. On the farm under study, a total of 32 animals were clinically affected, 12 died, 11 of them were 2year-old or younger.Our data confirm that vaccination with LAV is a useful tool to reduce the severity of the disease in endemic areas. However, clinical and sometimes fatal AHS can still affect young vaccinated horses, thus highlighting the necessity to better understand the immune response to AHSV and to dispose of more effective vaccines