Footprint of Positive Selection in Treponema pallidum subsp. pallidum Genome Sequences Suggests Adaptive Microevolution of the Syphilis Pathogen

In the rabbit model of syphilis, infection phenotypes associated with the Nichols and Chicago strains of Treponema pallidum (T. pallidum), though similar, are not identical. Between these strains, significant differences are found in expression of, and antibody responses to some candidate virulence factors, suggesting the existence of functional genetic differences between isolates. The Chicago strain genome was therefore sequenced and compared to the Nichols genome, available since 1998. Initial comparative analysis suggested the presence of 44 single nucleotide polymorphisms (SNPs), 103 small (≤3 nucleotides) indels, and 1 large (1204 bp) insertion in the Chicago genome with respect to the Nichols genome. To confirm the above findings, Sanger sequencing was performed on most loci carrying differences using DNA from Chicago and the Nichols strain used in the original T. pallidum genome project. A majority of the previously identified differences were found to be due to errors in the published Nichols genome, while the accuracy of the Chicago genome was confirmed. However, 20 SNPs were confirmed between the two genomes, and 16 (80.0%) were found in coding regions, with all being of non-synonymous nature, strongly indicating action of positive selection. Sequencing of 16 genomic loci harboring SNPs in 12 additional T. pallidum strains, (SS14, Bal 3, Bal 7, Bal 9, Sea 81-3, Sea 81-8, Sea 86-1, Sea 87-1, Mexico A, UW231B, UW236B, and UW249C), was used to identify “Chicago-“ or “Nichols -specific” differences. All but one of the 16 SNPs were “Nichols-specific”, with Chicago having identical sequences at these positions to almost all of the additional strains examined. These mutations could reflect differential adaptation of the Nichols strain to the rabbit host or pathoadaptive mutations acquired during human infection. Our findings indicate that SNPs among T. pallidum strains emerge under positive selection and, therefore, are likely to be functional in nature

Programming the Home and Enterprise WiFi with OpenSDWN

The quickly growing demand for wireless networks and the numerous application-specific requirements stand in stark contrast to today's inflexible management and operation of WiFi networks. In this paper, we present and evaluate OpenSDWN, a novel WiFi architecture based on an SDN/NFV approach. OpenSDWN exploits datapath programmability to enable service differentiation and fine-grained transmission control, facilitating the prioritization of critical applications. OpenSDWN implements per-client virtual access points and per-client virtual middleboxes, to render network functions more flexible and support mobility and seamless migration. OpenSDWN can also be used to out-source the control over the home network to a participatory interface or to an Internet Service Provider

SecuSpot: Toward cloud-assisted secure multi-tenant WiFi hotspot infrastructures

Despite the increasing popularity ofWiFi networks and the trend toward automated offloading of cellular traffic to WiFi (e.g., HotSpot 2.0), today's WiFi networks still provide a very poor actual coverage: a WiFi equipped device can typically connect to the Internet only through a very small fraction of the "available" access points. Accordingly, there is an enormous potential for multi-tenant WiFi hotspot architectures, which however also introduce more stringent requirements in terms of scalability and security. The latter is particularly critical, as HotSpots are often deployed in untrusted environments, e.g., physically accessible Access Points deployed in the user's premises (e.g., FON) or cafes. This paper proposes a Cloud-assisted multi-tenant and secure WiFi HotSpot infrastructure, called SecuSpot. SecuSpot is based on a modular access point and features interesting deployment flexibilities. These flexibilities can be exploited, e.g., to move security critical f unctions to the Cloud, and hence prevent eavesdropping even when deployed across untrusted Access Points. At the heart of SecuSpot lies a novel programmable wireless switch, the wSwitch. The wSwitch allows to (de-)multiplex the different tenants already on the HotSpot and to decouple essential security functions (association, authentication, and cryptography)