Superior Neutralizing Antibody Response and Protection in Mice Vaccinated with Heterologous DNA Prime and Virus Like Particle Boost against HPAI H5N1 Virus

Although DNA plasmid and virus-like particle (VLP) vaccines have been individually tested against highly pathogenic avian influenza (HPAI) H5N1 viruses, the combination of both vaccines into a heterologous prime-boost strategy against HPAI H5N1 viruses has not been reported before. of homologous H5N1 challenge even when the challenge was administrated at 60 days post the boost.These results provide strong support for clinical evaluation of heterologous DNA-VLP prime-boost strategy as a public health intervention against a possible H5N1 pandemic

Diarrheagenic pathogens in adults attending a hospital in Singapore.

BACKGROUND: Singapore's diarrhoeal notification system is based on specific pathogens. Official data may thus be skewed towards notifiable diseases. Limited information is available on the profiles of aetiological agents responsible for acute gastroenteritis (AGE) cases, especially among the adult population. To understand the frequency and distribution of potential causative agents of diarrheal disease in Singapore, we screened adults' stool samples collected from a large public hospital. METHODS: The stool samples were screened for 18 diarrheagenic pathogens using a combination of commercial multiplex polymerase chain reaction (PCR), in-house singleplex PCR and immunochromatographic assays. One hundred adult faecal samples that were collected from October 2013 to January 2014 for routine diagnostic purposes and submitted for culture at Tan Tock Seng Hospital, Singapore were used. RESULTS: Pathogens were detected in 32% of the samples. The predominant organisms encountered were norovirus genogroup II (11%), Aeromonas spp. (9%) and Campylobacter spp. (5%). One sample was positive for both verocytotoxigenic E. coli (VTEC) and E. coli O157:H7. Two other samples were positive for VTEC only, and one other sample was positive for E. coli O157:H7 only. Astrovirus, C. perfringens, Shigella spp. and toxigenic C. difficile were each detected in 2% of the samples. Cryptosporidium parvum, Giardia lamblia, group A rotavirus, Salmonella spp. and Vibrio spp. were each detected in 1% of the samples. No L. monocytogenes, Y. enterocolitica, enteric adenovirus, or norovirus genogroup I were detected. CONCLUSION: Our preliminary findings suggest that pathogens causing non-notifiable diseases might have contributed considerably to the adult hospitalised AGE cases. However, as the samples were from an adult hospital, the data obtained may not be representative of the whole community. Thus, a larger study to collect clinical samples and risk exposure data from primary healthcare clinics and children hospital is planned for, to gain a more holistic perspective on the epidemiology of AGE in Singapore. A larger study may also offer valuable insights for improving the approach of microbiological surveillance of food, as well as strategizing inspection efforts along the food supply chain by public health authorities

Eurasian Tree Sparrows, Risk for H5N1 Virus Spread and Human Contamination through Buddhist Ritual: An Experimental Approach

Background: The Highly Pathogenic Avian Influenza H5N1 virus has dramatically spread throughout Southeast Asia since its first detection in 1997. Merit Release Birds, such as the Eurasian Tree Sparrow, are believed to increase one's positive karma when kissed and released during Buddhist rituals. Since these birds are often in close contact with both poultry and humans, we investigated their potential role in the spread of H5N1 virus. Methodology/Principal Findings: Seven series of experiments were conducted in order to investigate the possible interactions between inoculated and exposed birds, including sparrow/sparrow, sparrow/chicken, duck/sparrow. Daily and post-mortem samples collected were tested for H5N1 virus by real-time RT-PCR and egg inoculation. When directly inoculated, Eurasian Tree Sparrows were highly susceptible to the H5N1 virus, with a fatality rate approaching 100% within 5 days post-inoculation. Although transmission of fatal infection between sparrows did not occur, seroconversion of the exposed birds was observed. Up to 100% chickens exposed to inoculated sparrows died of H5N1 infection, depending on the caging conditions of the birds, while a fatality rate of 50% was observed on sparrows exposed to infected ducks. Large quantities of H5N1 virus were detected in the sparrows, particularly in their feathers, from which infectious particles were recovered. Conclusions/Significance: Our study indicates that under experimental conditions, Eurasian Tree Sparrows are susceptible to H5N1 infection, either by direct inoculation or by contact with infected poultry. Their ability to transmit H5N1 infection to other birds is also demonstrated, suggesting that the sparrows may play a role in the dissemination of the virus. Finally, the presence of significant quantities of H5N1 virus on sparrows' feathers, including infectious particles, would suggest that Merit Release Birds represent a risk for human contamination in countries where avian influenza virus is circulating and where this religious ritual is practiced. © 2011 Gutiérrez et al.published_or_final_versio

A(H5N1) Virus Evolution in South East Asia

Highly Pathogenic Avian Influenza (HPAI) H5N1 virus is an ongoing public health and socio-economic challenge, particularly in South East Asia. H5N1 is now endemic in poultry in many countries, and represents a major pandemic threat. Here, we describe the evolution of H5N1 virus in South East Asia, the reassortment events leading to high genetic diversity in the region, and factors responsible for virus spread. The virus has evolved with genetic variations affecting virulence, drug-resistance, and adaptation to new host species. The constant surveillance of these changes is of primary importance in the global efforts of the scientific community

Biased mutational pattern and quasispecies hypothesis in H5N1 virus.

International audienceLike other RNA viruses, influenza viruses are subject to high mutation rates. Carrying segmented RNA genomes, their genetic variability is even higher. We aimed at analyzing the mutational events occurring during the infection of chickens by the Highly Pathogenic Avian Influenza (HPAI) H5N1 virus. We therefore studied the different sequences of two surface proteins, hemagglutinin (HA) and neuraminidase (NA), as well as two internal proteins, PB2 and NS. Three organs (lung, spleen, brain) were obtained from a chicken, experimentally infected with a lethal dose of HPAI H5N1 virus. Cloning these PCR fragments enabled us to investigate the mutations undergone by the virus after several replicative cycles. The first outcome is the presence of a strong mutational bias, resembling host-driven ADAR1 adenosine deamination, which is responsible for 81% of all mutations. Whereas the frequency of RNA dependent RNA polymerase-related mutations is compatible with the survival of the virus, the ADAR1-like activity usually strongly increases the mutation frequency into a level of "error catastrophe" in theory incompatible with virus survival. Nevertheless, the virus was successfully infective. HPAI H5N1 virus displayed traits in agreement with the quasispecies theory. The role of this quasispecies structure in successful infection and the superposition with the ADAR1-like response is discussed