Friends and Foes: The Dynamics of Dual Social Structures

This paper investigates the evolutionary dynamics of a dual social structure encompassing collaboration and conflict among corporate actors. We apply and advance structural balance theory to examine the formation of balanced and unbalanced dyadic and triadic structures, and to explore how these dynamics aggregate to shape the emergence of a global network. Our findings are threefold. First, we find that existing collaborative or conflictual relationships between two companies engender future relationships of the same type, but crowd out relationships of the different type. This results in (a) an increased likelihood of the formation of balanced (uniplex) relationships that combine multiple ties of either collaboration or conflict, and (b) a reduced likelihood of the formation of unbalanced (multiplex) relationships that combine collaboration and conflict between the same two firms. Second, we find that network formation is driven not by a pull toward balanced triads, but rather by a pull away from unbalanced triads. Third, we find that the observed micro-level dynamics of dyads and triads affect the structural segregation of the global network into two separate collaborative and conflictual segments of firms. Our empirical analyses used data on strategic partnerships and patent infringement and antitrust lawsuits in biotechnology and pharmaceuticals from 1996 to 2006

The nucleocapsid protein of rift valley fever virus is a potent human CD8+ T cell antigen and elicits memory responses

There is no licensed human vaccine currently available for Rift Valley Fever Virus (RVFV), a Category A high priority pathogen and a serious zoonotic threat. While neutralizing antibodies targeting the viral glycoproteins are protective, they appear late in the course of infection, and may not be induced in time to prevent a natural or bioterrorism-induced outbreak. Here we examined the immunogenicity of RVFV nucleocapsid (N) protein as a CD8(+) T cell antigen with the potential for inducing rapid protection after vaccination. HLA-A*0201 (A2)-restricted epitopic determinants were identified with N-specific CD8(+) T cells from eight healthy donors that were primed with dendritic cells transduced to express N, and subsequently expanded in vitro by weekly re-stimulations with monocytes pulsed with 59 15mer overlapping peptides (OLPs) across N. Two immunodominant epitopes, VT9 (VLSEWLPVT, N(121-129)) and IL9 (ILDAHSLYL, N165-173), were defined. VT9- and IL9-specific CD8(+) T cells identified by tetramer staining were cytotoxic and polyfunctional, characteristics deemed important for viral control in vivo. These peptides induced specific CD8(+) T cell responses in A2-transgenic mice, and more importantly, potent N-specific CD8(+) T cell reactivities, including VT9- and IL9-specific ones, were mounted by mice after a booster vaccination with the live attenuated RVF MP-12. Our data suggest that the RVFV N protein is a potent human T cell immunogen capable of eliciting broad, immunodominant CD8(+) T cell responses that are potentially protective. Understanding the immune responses to the nucleocapsid is central to the design of an effective RVFV vaccine irrespective of whether this viral protein is effective as a stand-alone immunogen or only in combination with other RVFV antigens