Definitive Hosts of Versteria Tapeworms (Cestoda : Taeniidae) Causing Fatal Infection in North America

We previously reported fatal infection of a captive Bornean orangutan with metacestodes of a novel taeniid tapeworm, Versteria sp. New data implicate mustelids as definitive hosts of these tapeworms in North America. At least 2 parasite genetic lineages circulate in North America, representing separate introductions from Eurasia.Peer reviewe

Differential Serotonergic Innervation of the Amygdala in Bonobos and Chimpanzees

Humans’ closest living relatives are bonobos (Pan paniscus) and chimpanzees (Pan troglodytes), yet these great ape species differ considerably from each other in terms of social behavior. While bonobos are more tolerant of conspecifics in competitive contexts and often use sexual behavior to mediate social interactions, chimpanzees more frequently employ aggression during conflicts and actively patrol territories between communities. Regulation of emotional responses is facilitated by the amygdala, which also modulates social decision-making, memory, and attention. Amygdala responsiveness is further regulated by the neurotransmitter serotonin. We hypothesized that the amygdala of bonobos and chimpanzees would differ in its neuroanatomical organization and serotonergic innervation. We measured volumes of regions and the length density of serotonin transporter-containing axons in the whole amygdala and its lateral, basal, accessory basal, and central nuclei. Results showed that accessory basal nucleus volume was larger in chimpanzees than bonobos. Of particular note, the amygdala of bonobos had more than twice the density of serotonergic axons than chimpanzees, with the most pronounced differences in the basal and central nuclei. These findings suggest that variation in serotonergic innervation of the amygdala may contribute to mediating the remarkable differences in social behavior exhibited by bonobos and chimpanzees

Virulence Criteria for Brucella abortus Strains as Determined by Interferon Regulatory Factor 1-Deficient Mice

Interferon regulatory factor 1-deficient (IRF-1(−/−)) mice infected with virulent Brucella abortus 2308 at 5 × 10(5) CFU developed acute hepatitis similar to many natural hosts but, unlike natural hosts, IRF-1(−/−) mice were unable to resolve infection and died. In contrast, IRF-1(−/−) mice survived when infected at 5 × 10(5) CFU with several attenuated Brucella strains (S19, RB51, cbp, and cyd). The survival of infected IRF-1(−/−) mice is likely a function of the level of virulence of each Brucella strain and the extent of retained immunity. Further, these findings suggest that adaptive immunity may be important to the survival of IRF-1(−/−) mice since attenuated Brucella strains can protect IRF-1(−/−) mice against lethal challenge with virulent Brucella. Using the IRF-1(−/−) mouse model, the following set of criteria were identified to define Brucella virulence: (i) the day of death for 50% of mice infected with 5 × 10(5)CFU of Brucella, (ii) the extent of liver toxicity, and (iii) the minimum immunizing dose of Brucella to protect against challenge with virulent S2308. Thus, IRF-1(−/−) mice are important to determining the level of Brucella virulence, to evaluating Brucella mutants for attenuation, and to investigating adaptive immunity in brucellosis