The potential for avian influenza H5N1 outbreaks has increased in recent years. Thus, it is paramount to develop novel strategies to alleviate death rates. Here we show that avian influenza A H5N1-infected patients exhibit markedly increased serum levels of angiotensin II. High serum levels of angiotensin II appear to be linked to the severity and lethality of infection, at least in some patients. In experimental mouse models, infection with highly pathogenic avian influenza A H5N1 virus results in downregulation of angiotensin-converting enzyme 2 (ACE2) expression in the lung and increased serum angiotensin II levels. Genetic inactivation of ACE2 causes severe lung injury in H5N1-challenged mice, confirming a role of ACE2 in H5N1-induced lung pathologies. Administration of recombinant human ACE2 ameliorates avian influenza H5N1 virus-induced lung injury in mice. Our data link H5N1 virus-induced acute lung failure to ACE2 and provide a potential treatment strategy to address future flu pandemics.

In this study, the prevalence of Enterocytozoon bieneusi in China was investigated. Twelve genotypes of E. bieneusi were identified, of which 10 were novel genotypes. Further, 41.6% of the genotypes were found in both humans and animals. This is the first report of E. bieneusi in China.Microsporidia are a diverse group of obligate intracellular pathogens consisting of approximately 1,300 formally described species in 160 genera that infect a wide range of invertebrate and vertebrate hosts, including humans (8,16). Enterocytozoon bieneusi, the most frequently diagnosed microsporidial species in humans, was first reported in an AIDS patient in 1985 (4). Over the last 2 decades, E. bieneusi has been detected in humans, other mammals, and birds in more than 30 countries (1,6,10,12). However, the prevalence of this parasite in China has been unclear.Currently, sequencing of the internal transcribed spacer (ITS) region of the rRNA gene is regarded as the standard method for species identification and genotyping of E. bieneusi isolates (17). More than 90 genotypes or variants of E. bieneusi that infect humans and animals have been identified (16). Recent molecular epidemiological studies indicated that some genotypes are host specific (17). Further, 8 genotypes (WL15, D, Peru6, EbpC, Peru10, Peru16, WL11, and Type IV) have been found in both humans and animals, indicating the potential for zoonotic transmission and the importance for surveillance of the epidemiology of E. bieneusi (17).We investigated the prevalence of E. bieneusi infection in humans and animals in China. A total of 220 fecal samples were collected. Among them, 40 fecal samples were from diarrheal children in the First Hospital of Jilin University in Changchun City, northeast China, 61 were from pigs in a livestock production facility, 26 were from dogs in a pet market, and 93 were from cows. Both human and animal samples were collected in the same area around Changchun City; however, the human samples were not from the same farm as the animal samples. The collection of human and animal stool samples was approved by the Ethics Committee of the Institute of Zoonosis, Jilin University. DNA was extracted from each fecal sample with a modified protocol as described previously (7).A nested PCR with primers based on the specific ITS sequences of E. bieneusi was applied for pathogen identification as previously reported (2, 5). E. bieneusi ITS sequences were determined, and a multiple alignment was performed using the ClustalX program. To assess the extent of genetic diversity and evolutionary relationships among the previously known genotypes of Enterocytozoon spp. and the novel genotypes, a neighbor-joining tree based on the evolutionary distances calculated by the Kimura two-parameter model (15) was constructed using the MEGA 4.0 program (19).E. bieneusi-specific sequences were amplified from 56 of the 220 fecal samples (9 from humans, 2 from dogs, 35 from cows, and 10 from pigs) ( Table 1). The 56 sequences were classified into 12 genotypes, which include...

The genome sequences of 175 Ebola virus from five districts in Sierra Leone, collected during September–November 2014, show that the rate of virus evolution seems to be similar to that observed during previous outbreaks and that the genetic diversity of the virus has increased substantially, with the emergence of several novel lineages. Supplementary information The online version of this article (doi:10.1038/nature14490) contains supplementary material, which is available to authorized users.

Infection with laboratory-attenuated rabies virus (RABV) enhances blood-brain barrier (BBB) permeability, which has been demonstrated to be an important factor for host survival, since it allows immune effectors to enter the central nervous system (CNS) and clear RABV. To probe the mechanism by which RABV infection enhances BBB permeability, the expression of tight junction (TJ) proteins in the CNS was investigated following intracranial inoculation with laboratory-attenuated or wild-type (wt) RABV. BBB permeability was significantly enhanced in mice infected with laboratory-attenuated, but not wt, RABV. The expression levels of TJ proteins (claudin-5, occludin, and zonula occludens-1) were decreased in mice infected with laboratoryattenuated, but not wt, RABV, suggesting that enhancement of BBB permeability is associated with the reduction of TJ protein expression in RABV infection. RABV neither infects the brain microvascular endothelial cells (BMECs) nor modulates the expression of TJ proteins in BMECs. However, brain extracts prepared from mice infected with laboratory-attenuated, but not wt, RABV reduced TJ protein expression in BMECs. It was found that brain extracts from mice infected with laboratory-attenuated RABV contained significantly higher levels of inflammatory chemokines/cytokines than those from mice infected with wt RABV. Pathway analysis indicates that gamma interferon (IFN-␥) is located in the center of the cytokine network in the RABV-infected mouse brain, and neutralization of IFN-␥ reduced both the disruption of BBB permeability in vivo and the downregulation of TJ protein expression in vitro. These findings indicate that the enhancement of BBB permeability and the reduction of TJ protein expression are due not to RABV infection per se but to virus-induced inflammatory chemokines/cytokines. IMPORTANCEPrevious studies have shown that infection with only laboratory-attenuated, not wild-type, rabies virus (RABV) enhances bloodbrain barrier (BBB) permeability, allowing immune effectors to enter the central nervous system (CNS) and clear RABV from the CNS. This study investigated the mechanism by which RABV infection enhances BBB permeability. It was found that RABV infection enhances BBB permeability by downregulation of tight junction (TJ) protein expression in the brain microvasculature. It was further found that it is not RABV infection per se but the chemokines/cytokines induced by RABV infection that downregulate the expression of TJ proteins and enhance BBB permeability. Blocking some of these cytokines, such as IFN-␥, ameliorated both the disruption of BBB permeability and the downregulation of TJ protein expression. These studies may provide a foundation for developing therapeutics for clinical rabies, such as medication that could be used to enhance BBB permeability.

The threat of a new influenza pandemic has existed since 1997, when the highly pathogenic H5N1 strain of avian influenza A virus infected humans in Hong Kong and spread across Asia, where it continued to infect poultry and people. The human mortality rate of H5N1 infection is about 60%, whereas that of seasonal H1N1 infection is less than 0.1%. The high mortality rate associated with H5N1 infection is predominantly a result of respiratory failure caused by acute lung injury; however, how viral infection contributes to this disease pathology is unclear. Here, we used electron microscopy to show the accumulation of autophagosomes in H5N1-infected lungs from a human cadaver and mice, as well as in infected A549 human epithelial lung cells. We also showed that H5N1, but not seasonal H1N1, induced autophagic cell death in alveolar epithelial cells through a pathway involving the kinase Akt, the tumor suppressor protein TSC2, and the mammalian target of rapamycin. Additionally, we suggest that the hemagglutinin protein of H5N1 may be responsible for stimulating autophagy. When applied prophylactically, reagents that blocked virus-induced autophagic signaling substantially increased the survival rate of mice and substantially ameliorated the acute lung injury and mortality caused by H5N1 infection. We conclude that the autophagic cell death of alveolar epithelial cells likely plays a crucial role in the high mortality rate of H5N1 infection, and we suggest that autophagy-blocking agents might be useful as prophylactics and therapeutics against infection of humans by the H5N1 virus.