Cláudia Balzan

Moraxella bovoculi em casos de ceratoconjuntivite infecciosa bovina no Rio Grande do Sul

Infectious keratoconjunctivitis (IK), although rarely fatal, results in significant economic losses for cattle and sheep farmers. The main causative agents of this disorder are Moraxella bovis and Moraxella ovis. In 2007, a new species also responsible for IK was described. This newly described pathogen, called Moraxella bovoculi, was never reported in Brazil. Therefore, the aim of this study was confirmed the M. bovoculi among the samples analyzed. For this, 54 isolates of Moraxella spp. from clinical samples derived from 34 cattle and 18 sheep, sent to the laboratory of bacteriology from 1991 to 2011 was characterized. Differentiation among the species was based on genotypic characteristics, using partial amplification of 16S-23S intergenic region and cleavage products of amplification with enzyme RsaI. Results showed that 25 isolates (46%) were characterized as M. bovis, 17 (32%) as M. ovis, and 12 (22%) as M. bovoculi. This means that M. bovoculi is present among cattle herds in Rio Grande do Sul and, therefore, in Brazil.

Distinct Campylobacter fetus lineages adapted as livestock pathogens and human pathobionts in the intestinal microbiota.

Campylobacter fetus is a venereal pathogen of cattle and sheep, and an opportunistic human pathogen. It is often assumed that C. fetus infection occurs in humans as a zoonosis through food chain transmission. Here we show that mammalian C. fetus consists of distinct evolutionary lineages, primarily associated with either human or bovine hosts. We use whole-genome phylogenetics on 182 strains from 17 countries to provide evidence that C. fetus may have originated in humans around 10,500 years ago and may have “jumped” into cattle during the livestock domestication period. We detect C. fetus genomes in 8% of healthy human fecal metagenomes, where the human-associated lineages are the dominant type (78%). Thus, our work suggests that C. fetus is an unappreciated human intestinal pathobiont likely spread by human to human transmission. This genome-based evolutionary framework will facilitate C. fetus epidemiology research and the development of improved molecular diagnostics and prevention schemes for this neglected pathogen.Human infections with Campylobacter fetus are often assumed to be derived from livestock. Here, Iraola et al. provide evidence that healthy humans may act as carriers and dispersers, and C. fetus may have originated in humans as an intestinal pathobiont and then adapted as a livestock pathogen.

Antigenic characterization of Moraxella bovis, Moraxella bovoculi and Moraxella ovis strains with potential use in vaccines

Moraxella bovis is historically known as the primary agent of infectious bovine keratoconjunctivitis (IBK). However, Moraxella bovoculi and Moraxella ovis are also reported to be involved in the pathogenesis of IBK, therefore, these three species should be included in the development of a new vaccine with a broad-spectrum protection against the disease natural challenge. In this study we investigated the antigenic properties of clinical isolates and reference strains of M. bovis, M. bovoculi and M. ovis using a novel in vitro approach for vaccine evaluation based on two techniques, flow cytometry and western blotting (WB). Here, we demonstrated that rabbit antisera produced against reference M. bovis strain and commercial bacterin showed low number of IgG with capacity to recognize a panel of heterologous strains composed by M. bovoculi and M. ovis. On the other hand, the antisera generated against two clinical isolates of M. ovis (Mov2 and Mov3) presented high cross-reactivity levels against all M. ovis and M. bovis strains evaluated. Similarly, the antisera against Mbv3 (clinical isolate of M. bovoculi) had high levels of IgG associated on the surface of all M. bovoculi strains and most of the M. ovis strains analyzed. The WB analysis demonstrated that Moraxella spp. has multiple immunogenic antigens and most of them are shared between the three species. Based on the cross-reactivity analysis and considering the relative number of IgGs associated on the bacterial surface, we suggest that a multivalent vaccine including Mbv3, Mov2 and Mov3 strains may provide a strong and broad protection against all strains involved in IBK outbreaks.