Search

Avian influenza virus (AIV) surveillance in Antarctica during 2013 revealed the prevalence of evolutionarily distinct influenza viruses of the H11N2 subtype in Adélie penguins. Here we present results from the continued surveillance of AIV on the Antarctic Peninsula during 2014 and 2015. In addition to the continued detection of H11 subtype viruses in a snowy sheathbill during 2014, we isolated a novel H5N5 subtype virus from a chinstrap penguin during 2015. Gene sequencing and phylogenetic analysis revealed that the H11 virus detected in 2014 had a >99.1% nucleotide similarity to the H11N2 viruses isolated in 2013, suggesting the continued prevalence of this virus in Antarctica over multiple years. However, phylogenetic analysis of the H5N5 virus showed that the genome segments were recently introduced to the continent, except for the NP gene, which was similar to that in the endemic H11N2 viruses. Our analysis indicates geographically diverse origins for the H5N5 virus genes, with the majority of its genome segments derived from North American lineage viruses but the neuraminidase gene derived from a Eurasian lineage virus. In summary, we show the persistence of AIV lineages in Antarctica over multiple years, the recent introduction of gene segments from diverse regions, and reassortment between different AIV lineages in Antarctica, which together significantly increase our understanding of AIV ecology in this fragile and pristine environment. IMPORTANCE Analysis of avian influenza viruses (AIVs) detected in Antarctica reveals both the relatively recent introduction of an H5N5 AIV, predominantly of North American-like origin, and the persistence of an evolutionarily divergent H11 AIV. These data demonstrate that the flow of viruses from North America may be more common than initially thought and that, once introduced, these AIVs have the potential to be maintained within Antarctica. The future introduction of AIVs from North America into the Antarctic Peninsula is of particular concern given that highly pathogenic H5Nx viruses have recently been circulating among wild birds in parts of Canada and the Unites States following the movement of these viruses from Eurasia via migratory birds. The introduction of a highly pathogenic influenza virus in penguin colonies within Antarctica might have devastating consequences.

Campylobacter jejuni is a recognized and common gastrointestinal pathogen in most parts of the world. Human infections are often food borne, and the bacterium is frequent among poultry and other food animals. However, much less is known about the epidemiology of C. jejuni in the environment and what mechanisms the bacterium depends on to tolerate low pH. The sensitive nature of C. jejuni stands in contrast to the fact that it is difficult to eradicate from poultry production, and even more contradictory is the fact that the bacterium is able to survive the acidic passage through the human stomach. Here we expand the knowledge on C. jejuni acid tolerance by looking at protozoa as a potential epidemiological pathway of infection. Our results showed that when C. jejuni cells were coincubated with Acanthamoeba polyphaga in acidified phosphate-buffered saline (PBS) or tap water, the bacteria could tolerate pHs far below those in their normal range, even surviving at pH 4 for 20 h and at pH 2 for 5 h. Interestingly, moderately acidic conditions (pH 4 and 5) were shown to trigger C. jejuni motility as well as to increase adhesion/internalization of bacteria into A. polyphaga . Taken together, the results suggest that protozoa may act as protective hosts against harsh conditions and might be a potential risk factor for C. jejuni infections. These findings may be important for our understanding of C. jejuni passage through the gastrointestinal tract and for hygiene practices used in poultry settings.

In this study, we present a novel method to isolate and enrich low concentrations of Campylobacter pathogens. This method, Acanthamoeba - Campylobacter coculture (ACC), is based on the intracellular survival and multiplication of Campylobacter species in the free-living protozoan Acanthamoeba polyphaga . Four of the Campylobacter species relevant to humans and livestock, Campylobacter jejuni , C. coli , C. lari , and C. hyointestinalis , were effectively enriched by the coculture method, with growth rates comparable to those observed in other Campylobacter enrichment media. Studying six strains of C. jejuni isolated from different sources, we found that all of the strains could be enriched from an inoculum of fewer than 10 bacteria. The sensitivity of the ACC method was not negatively affected by the use of Campylobacter -selective antibiotics in the culture medium, but these were effective in suppressing the growth of seven different bacterial species added at a concentration of 10 4 CFU/ml of each species as deliberate contamination. The ACC method has advantages over other enrichment methods as it is not dependent on a microaerobic milieu and does not require the use of blood or other oxygen-quenching agents. Our study found the ACC method to be a promising tool for the enrichment of Campylobacter species, particularly from water samples with low bacterial concentrations.

The gut microbiota is essential for human health, but very little is known about how the composition of this ecosystem can influence and respond to bacterial infections. Here we address this by prospectively studying the gut microbiota composition before, during, and after natural Campylobacter infection in exposed poultry abattoir workers. The gut microbiota composition was analyzed with 16S amplicon sequencing of fecal samples from poultry abattoir workers during the peak season of Campylobacter infection in Sweden. The gut microbiota compositions were compared between individuals who became culture positive for Campylobacter and those who remained negative. Individuals who became Campylobacter positive had a significantly higher abundance of Bacteroides (P = 0.007) and Escherichia (P = 0.002) species than those who remained culture negative. Furthermore, this group had a significantly higher abundance of Phascolarctobacterium (P = 0.017) and Streptococcus (P = 0.034) sequences than the Campylobacter-negative group, which had an overrepresentation of Clostridiales (P = 0.017), unclassified Lachnospiraceae (P = 0.008), and Anaerovorax (P = 0.015) sequences. Intraindividual comparisons of the fecal microbiota compositions yielded small differences over time in Campylobacter-negative participants, but significant long-term changes were found in the Campylobacter-positive group (P < 0.005). The results suggest that the abundance of specific genera in the microbiota reduces resistance to Campylobacter colonization in humans and that Campylobacter infection can have long-term effects on the composition of the human fecal microbiota., IMPORTANCE Studies using mouse models have made important contributions to our understanding of the role of the gut microbiota in resistance to bacterial enteropathogen colonization. The relative abundances of Escherichia coli and Bacteroides species have been pointed out as important determinants of susceptibility to Gram-negative pathogens in general and Campylobacter infection in particular. In this study, we assessed the role of the human gut microbiota in resistance to Campylobacter colonization by studying abattoir workers that are heavily exposed to these bacteria. Individuals with a certain composition of the gut microbiota became culture positive for Campylobacter. As their microbiotas were characterized by high abundances of Bacteroides spp. and E. coli, well in line with the findings with mouse models, these bacterial species likely play an important role in colonization resistance also in humans.