Characterization of a Human Antibody Fragment Fab and Its Calcium Phosphate Nanoparticles that Inhibit Rabies Virus Infection with Vaccine

Recombinant antibody phage display technology has been used to mimic many aspects of the processes that govern the generation and selection of high-affinity natural human antibodies in the human immune system, especially for infectious disease prophylaxis. An anti-rabies virus immunized phage-display Fab library was constructed from peripheral blood lymphocytes from vaccinated volunteers. The immunized antibody library, with a diversity of 6.7×108, was used to select and produce antibodies that bound to rabies virus glycoprotein. After five rounds of immobilized fixed rabies virion panning, four unique DNA sequences were found in the higher binding clones, and only one, Fab094, showed neutralization activity. Fab094 components were analyzed by ELISA, immunoprecipitation and immunofluorescent staining. ELISA and immunofluorescence showed that Fab094 bound specifically to rabies virions. Immunoprecipitation and mass spectrometry showed that Fab094 reacted with rabies virus glycoprotein. To improve the penetration power of Fab094 antibodies, we developed Fab094 calcium phosphate nanoparticles (Fab094-CPNPs) and tested their efficacy. The rapid fluorescent focus inhibition test indicated that the neutralizing antibody titers of Fab094 and Fab094-CPNPs were reached at 200.17 IU/Kg and 246.12 IU/Kg, respectively. These findings were confirmed in vivo in a Kunming mouse challenge model. Our results demonstrate that human Fab094 and Fab094-CPNPs are efficacious candidate drugs to replace rabies immunoglobulin in post-exposure prophylaxis (PEP)

On the Origin of Tibetans and Their Genetic Basis in Adapting High-Altitude Environments

Since their arrival in the Tibetan Plateau during the Neolithic Age, Tibetans have been well-adapted to extreme environmental conditions and possess genetic variation that reflect their living environment and migratory history. To investigate the origin of Tibetans and the genetic basis of adaptation in a rigorous environment, we genotyped 30 Tibetan individuals with more than one million SNP markers. Our findings suggested that Tibetans, together with the Yi people, were descendants of Tibeto-Burmans who diverged from ancient settlers of East Asia. The valleys of the Hengduan Mountain range may be a major migration route. We also identified a set of positively-selected genes that belong to functional classes of the embryonic, female gonad, and blood vessel developments, as well as response to hypoxia. Most of these genes were highly correlated with population-specific and beneficial phenotypes, such as high infant survival rate and the absence of chronic mountain sickness

a real-time key recovery attack on the lightweight stream cipher a2u2

The stream cipher A2U2 proposed by David et al. [7] is one of lightweight cipher primitives. In this paper we present a real-time key recovery attack on A2U2 under the known-plaintext-attack model, which only needs at most 210 consecutive ciphertext bits and its corresponding plaintext with the time complexity about 224.7. Our result is much better than that of the attack proposed by M. Abdelraheem et al. in [9] whose complexity is O(2 49 x C), where C is the complexity of solving a sparse quadratic equation system on 56 unknown key bits. Furthermore we provide a new approach to solving the above sparse quadratic equation system, which reduces the complexity C to a very small constant. Finally we do an entire experiment on a PC and recover all bits of a random key in a few seconds. © Springer-Verlag 2012.The stream cipher A2U2 proposed by David et al. [7] is one of lightweight cipher primitives. In this paper we present a real-time key recovery attack on A2U2 under the known-plaintext-attack model, which only needs at most 210 consecutive ciphertext bits and its corresponding plaintext with the time complexity about 224.7. Our result is much better than that of the attack proposed by M. Abdelraheem et al. in [9] whose complexity is O(2 49 x C), where C is the complexity of solving a sparse quadratic equation system on 56 unknown key bits. Furthermore we provide a new approach to solving the above sparse quadratic equation system, which reduces the complexity C to a very small constant. Finally we do an entire experiment on a PC and recover all bits of a random key in a few seconds. © Springer-Verlag 2012

on guess and determine analysis of rabbit

Rabbit is a stream cipher proposed by M. Boesgaard et al., and has been selected into the final portfolio after three evaluation phases of the ECRYPT Stream Cipher Project (eSTREAM). So far only a few papers studied its security besides a series of white papers by the designers of Rabbit. Recently we presented a new idea to evaluate the security of a word-oriented stream cipher algorithm from a smaller data granularity instead of its original data granularity and applied it successfully to the stream cipher SOSEMANUK. In this work we apply the same idea to the Rabbit algorithm and analyze its security in resistance against the guess and determine attack from the view point of byte units. As a result, we present two new approaches of solving all x(j,t)+1's and g(j,t)'s from the next-state function and the extraction scheme of Rabbit, whose complexities are 2(166) and 2(140.68) respectively, which are dramatically lower than those proposed by Lu et al. (2(192) and 2(174) resp.) at ISC 2008. Finally based on the above new results we propose a byte-based guess and determine attack on Rabbit, which only needs a small segment of known key stream to recover the whole internal state of Rabbit with time complexity 2(242). Though the complexity of our attack is far higher than that of a brute force (2(128)), we believe that some new techniques adopted in this paper are of interest for future work on Rabbit.Natural Science Foundation of China60833008, 60902024; National 973 Program2007CB807902Rabbit is a stream cipher proposed by M. Boesgaard et al., and has been selected into the final portfolio after three evaluation phases of the ECRYPT Stream Cipher Project (eSTREAM). So far only a few papers studied its security besides a series of white papers by the designers of Rabbit. Recently we presented a new idea to evaluate the security of a word-oriented stream cipher algorithm from a smaller data granularity instead of its original data granularity and applied it successfully to the stream cipher SOSEMANUK. In this work we apply the same idea to the Rabbit algorithm and analyze its security in resistance against the guess and determine attack from the view point of byte units. As a result, we present two new approaches of solving all x(j,t)+1's and g(j,t)'s from the next-state function and the extraction scheme of Rabbit, whose complexities are 2(166) and 2(140.68) respectively, which are dramatically lower than those proposed by Lu et al. (2(192) and 2(174) resp.) at ISC 2008. Finally based on the above new results we propose a byte-based guess and determine attack on Rabbit, which only needs a small segment of known key stream to recover the whole internal state of Rabbit with time complexity 2(242). Though the complexity of our attack is far higher than that of a brute force (2(128)), we believe that some new techniques adopted in this paper are of interest for future work on Rabbit

improved key recovery attacks on reduced-round salsa20 and chacha

Salsa20 is a stream cipher designed by Bernstein in 2005 and Salsa20/12 has been selected into the final portfolio of the eSTREAM Project. ChaCha is a variant of Salsa20 with faster diffusion for similar performance. The previous best results on Salsa20 and ChaCha proposed by Aumasson et al. exploits the differential properties combined with the probabilistic neutral bits (PNB). In this paper, we extend their approach by considering a new type of distinguishers, named (column and row) chaining distinguishers. Besides, we exhibit new high probability second-order differential trails not covered by the previous methods, generalize the notion of PNB to probabilistic neutral vectors (PNV) and show that the set of PNV is no smaller than that of PNB. Based on these findings, we present improved key recovery attacks on reduced-round Salsa20 and ChaCha. Both time and data complexities of our attacks are smaller than those of the best former results. © 2013 Springer-Verlag.Salsa20 is a stream cipher designed by Bernstein in 2005 and Salsa20/12 has been selected into the final portfolio of the eSTREAM Project. ChaCha is a variant of Salsa20 with faster diffusion for similar performance. The previous best results on Salsa20 and ChaCha proposed by Aumasson et al. exploits the differential properties combined with the probabilistic neutral bits (PNB). In this paper, we extend their approach by considering a new type of distinguishers, named (column and row) chaining distinguishers. Besides, we exhibit new high probability second-order differential trails not covered by the previous methods, generalize the notion of PNB to probabilistic neutral vectors (PNV) and show that the set of PNV is no smaller than that of PNB. Based on these findings, we present improved key recovery attacks on reduced-round Salsa20 and ChaCha. Both time and data complexities of our attacks are smaller than those of the best former results. © 2013 Springer-Verlag

Cryptanalysis of Helix and Phelix revisited

Helix, designed by Ferguson et al., is a high-speed asynchronous stream cipher with a built-in MAC functionality. At FSE 2004, Muller presented two attacks on Helix. Motivated by these attacks, Phelix was proposed and selected as a Phase 2 focus cipher for both Profile 1 and Profile 2 by the eSTREAM project, but was not advanced to Phase 3 mainly due to a key recovery attack by Wu and Preneel when the prohibition against reusing a nonce is violated. In this paper, we study the security of Helix and Phelix in the more realistic chosen nonce model. We first point out a flaw in Muller's second attack, which results in the failure of his attack. Then we propose our distinguishing attack on Helix with a data complexity of 2132, faster than exhaustive search when the key length is larger than 132 bits. Furthermore, when the maximal length of output keystream is extended, the data complexity can be reduced to 2 127 and we also can construct a key recovery attack with a data complexity of 2163. Since this flaw is overlooked by the designers of Phelix, we can extend the distinguishing attack to Phelix with the same complexity, which shows that Phelix fails to strengthen Helix against internal state collision attacks. Our results provide new insights on the design of such dedicated ciphers with built-in authentication. © 2013 Springer-Verlag.Helix, designed by Ferguson et al., is a high-speed asynchronous stream cipher with a built-in MAC functionality. At FSE 2004, Muller presented two attacks on Helix. Motivated by these attacks, Phelix was proposed and selected as a Phase 2 focus cipher for both Profile 1 and Profile 2 by the eSTREAM project, but was not advanced to Phase 3 mainly due to a key recovery attack by Wu and Preneel when the prohibition against reusing a nonce is violated. In this paper, we study the security of Helix and Phelix in the more realistic chosen nonce model. We first point out a flaw in Muller's second attack, which results in the failure of his attack. Then we propose our distinguishing attack on Helix with a data complexity of 2132, faster than exhaustive search when the key length is larger than 132 bits. Furthermore, when the maximal length of output keystream is extended, the data complexity can be reduced to 2 127 and we also can construct a key recovery attack with a data complexity of 2163. Since this flaw is overlooked by the designers of Phelix, we can extend the distinguishing attack to Phelix with the same complexity, which shows that Phelix fails to strengthen Helix against internal state collision attacks. Our results provide new insights on the design of such dedicated ciphers with built-in authentication. © 2013 Springer-Verlag

The Fab Fragment of a Humanized Anti-Toll Like Receptor 4 (TLR4) Monoclonal Antibody Reduces the Lipopolysaccharide Response via TLR4 in Mouse Macrophage

Lipopolysaccharides (LPS) can induce acute inflammation, sepsis, or chronic inflammatory disorders through the Toll receptor 4 (TLR4) signaling pathway. The TLR4/MD2 (myeloid differentiation protein 2) complex plays a major role in the immune response to LPS. However, there is not a good method to suppress the immune response induced by LPS via this complex in macrophages. In this article, we aimed to evaluate the effects of humanized anti-TLR4 monoclonal antibodies on LPS-induced responses in mouse macrophages. The peritoneal macrophages of mice were incubated with anti-TLR4 monoclonal antibodies and stimulated with LPS. The expression levels of cytokines were analyzed by quantitative polymerase chain reaction and enzyme-linked immunosorbent assays. Additionally, activation of various signaling pathways was evaluated by Western blotting. The results showed that the humanized anti-TLR4 monoclonal antibody blocked the inflammatory cytokines expression at both the mRNA and protein level. We also found that the Fab fragment significantly inhibited the nuclear factor kappaB signaling pathway by reducing the phosphorylation of the inhibitor of kappaBalpha and decreasing the translocation of p65, resulting in the suppression of p38, extracellular signal-regulated kinase 1/2, c-Jun N-terminal kinase 1/2, and IFN-β regulatory factor 3 phosphorylation. Therefore, our study showed that this humanized anti-TLR4 monoclonal antibody could effectively protect against LPS-induced responses by blocking the TLR4 signaling pathway in mouse peritoneal macrophages