In human evolution, social group living and Pavlovian fear conditioning have evolved as adaptive mechanisms promoting survival and reproductive success. The evolutionarily conserved hypothalamic peptide oxytocin is a key modulator of human sociality, but its effects on fear conditioning are still elusive. In the present randomized controlled study involving 97 healthy male subjects, we therefore employed functional magnetic resonance imaging and simultaneous skin conductance response (SCR) measures to characterize the modulatory influence of intranasal oxytocin (24 IU) on Pavlovian fear conditioning. We found that the peptide strengthened conditioning on both the behavioral and neural levels. Specifically, subjects exhibited faster task-related responses and enhanced SCRs to fear-associated stimuli in the late phase of conditioning, which was paralleled by heightened activity in cingulate cortex subregions in the absence of changes in amygdala function. This speaks against amygdalocentric views of oxytocin having pure anxiolytic-like effects. Instead, it suggests that the peptide enables extremely rapid and flexible adaptation to fear signals in social contexts, which may confer clear evolutionary advantages but could also elevate vulnerability for the pathological sequelae of interpersonal trauma.

Chronic infection with the hepatitis B virus (HBV) affects an estimated 257 million people worldwide and can lead to liver diseases such as cirrhosis and liver cancer. Viral replication is generally considered not to be cytopathic, and although some HBV proteins may have direct carcinogenic effects, the majority of HBV infection-related disease is related to chronic inflammation resulting from disrupted antiviral responses and aberrant innate immune reactions. Like all cells, healthy and HBV-infected cells communicate with each other, as well as with other cell types, such as innate and adaptive immune cells. They do so by both interacting directly and by secreting factors into their environment. Such factors may be small molecules, such as metabolites, single viral proteins or host proteins, but can also be more complex, such as virions, protein complexes, and extracellular vesicles. The latter are small, membrane-enclosed vesicles that are exchanged between cells, and have recently gained a lot of attention for their potential to mediate complex communication and their potential for therapeutic repurposing. Here, we review how HBV infection affects the communication between HBV-infected cells and cells in their environment. We discuss the impact of these interactions on viral persistence in chronic infection, as well as their relation to HBV infection-related pathology.