Interleukin-17A mediates acquired immunity to pneumococcal colonization

Although anticapsular antibodies confer serotype-specific immunity to pneumococci, children increase their ability to clear colonization before these antibodies appear, suggesting involvement of other mechanisms. We previously reported that intranasal immunization of mice with pneumococci confers CD4+ T cell-dependent, antibody- and serotype-independent protection against colonization. Here we show that this immunity, rather than preventing initiation of carriage, accelerates clearance over several days, accompanied by neutrophilic infiltration of the nasopharyngeal mucosa. Adoptive transfer of immune CD4+ T cells was sufficient to confer immunity to na?ve RAG1(-/-) mice. A critical role of interleukin (IL)-17A was demonstrated: mice lacking interferon-gamma or IL-4 were protected, but not mice lacking IL-17A receptor or mice with neutrophil depletion. In vitro expression of IL-17A in response to pneumococci was assayed: lymphoid tissue from vaccinated mice expressed significantly more IL-17A than controls, and IL-17A expression from peripheral blood samples from immunized mice predicted protection in vivo. IL-17A was elicited by pneumococcal stimulation of tonsillar cells of children or adult blood but not cord blood. IL-17A increased pneumococcal killing by human neutrophils both in the absence and in the presence of antibodies and complement. We conclude that IL-17A mediates pneumococcal immunity in mice and probably in humans; its elicitation in vitro could help in the development of candidate pneumococcal vaccines.     

Winter diets of wolfCanis lupus and lynxLynx lynx in Estonia and Latvia

Winter diets of wolfCanis lupus Linnaeus, 1758 and lynxLynx lynx Linnaeus, 1758 in Latvia and Estonia were investigated in 1997–2000 based on stomach contents of hunted animals and scats. Ungulates appeared to be the staple food for both predators. Lynx diet to a high extent consisted of cervids (Estonia 52% frequency of prey, Latvia 88%), roe deer dominating. Mountain hareLepus timidus made up from 9% (Latvia) to 31% (Estonia) of the lynx diet, and red foxVulpes vulpes 7% in Estonian sample. Wolf diet was more diverse; besides cervids (44% in Latvia, 63% in Estonia) it included wild boar Sus scrofa (32% in Latvia, 17% in Estonia), carrion, small rodents, and other food items. Proportion of empty stomachs was high both in wolves (37%) and lynxes (35%) in Latvia. Range of stomach content weights varied from zero to more than 4 kg in wolves and almost 1.5 kg in lynx. Pianka’s indices of food niche overlapped significantly between species and countries (0.85–0.99).     

Coat Polymorphism in Eurasian Lynx: Adaptation to Environment or Phylogeographic Legacy?

Journal of Mammalian Evolution - We studied the relationship between the variability and contemporary distribution of pelage phenotypes in one of most widely distributed felid species and an array...