Project description:The swine-origin influenza A (H1N1) virus that appeared in 2009 and was first found in human beings in Mexico, is a reassortant with at least three parents. Six of the genes are closest in sequence to those of H1N2 'triple-reassortant' influenza viruses isolated from pigs in North America around 1999-2000. Its other two genes are from different Eurasian 'avian-like' viruses of pigs; the NA gene is closest to H1N1 viruses isolated in Europe in 1991-1993, and the MP gene is closest to H3N2 viruses isolated in Asia in 1999-2000. The sequences of these genes do not directly reveal the immediate source of the virus as the closest were from isolates collected more than a decade before the human pandemic started. The three parents of the virus may have been assembled in one place by natural means, such as by migrating birds, however the consistent link with pig viruses suggests that human activity was involved. We discuss a published suggestion that unsampled pig herds, the intercontinental live pig trade, together with porous quarantine barriers, generated the reassortant. We contrast that suggestion with the possibility that laboratory errors involving the sharing of virus isolates and cultured cells, or perhaps vaccine production, may have been involved. Gene sequences from isolates that bridge the time and phylogenetic gap between the new virus and its parents will distinguish between these possibilities, and we suggest where they should be sought. It is important that the source of the new virus be found if we wish to avoid future pandemics rather than just trying to minimize the consequences after they have emerged. Influenza virus is a very significant zoonotic pathogen. Public confidence in influenza research, and the agribusinesses that are based on influenza's many hosts, has been eroded by several recent events involving the virus. Measures that might restore confidence include establishing a unified international administrative framework coordinating surveillance, research and commercial work with this virus, and maintaining a registry of all influenza isolates.

Project description:In June 2009, the World Health Organization declared the first influenza pandemic of the 21st century, due to the emergence and rapid spread of new swine origin H1N1 influenza A virus. In contrast to seasonal influenza infections, which typically cause morbidity and mortality in the elderly, this virus caused severe infection in young adults and not the elderly. This phenomenon was attributed to the presence of cross-neutralizing antibodies acquired by older individuals from previous exposure to swine origin influenza. However, this hypothesis could not be empirically tested using clinical data. To address this question, we investigated viral replication and the development of the immune response in naï12 years old) and aged (20 to 24 years old) female rhesus macaques infected with A/California/04/2009 (H1N1), one of the circulating pandemic strains in 2009. We compared viral loads as well as the kinetics and magnitude of the adaptive immune response in peripheral blood and bronchoalveolar lavage samples (BAL) collected longitudinally for 99 days post-infection. Although, adult animals exhibited earlier T cell responses in peripheral blood, aged animals generated a robust T cell response with comparable kinetics and magnitude as those observed in young animals in BAL. Moreover, aged animals generated a higher hemagglutination inhibition titer compared to young animals. We also measured the concentration of several cytokines in BAL supernatant. With the exception of IL-8, which was higher in aged animals, we found no differences in IFNa, IFNb, TNFa, IL-1r, IL-6, IL-15, IL-17, or MCP1 levels. Finally, we compared gene expression infection using microarray analysis of BAL samples taken on days 0, 4, 7, 10, and 14 pi. Our analyses revealed that the largest difference in host response between aged and young animals was detected day 4 post-infection, with significant enrichment for genes associated with inflammation, the innate immune response, and T cell activation in aged animals. The ability of aged animals to generate a robust immune response, especially antibody response, following infection with 2009 H1N1 virus could explain the lack of morbidity normally observed with seasonal influenza viruses in this vulnerable population.

Project description:UnlabelledThe emergence in humans of the A(H1N1)pdm09 influenza virus, a complex reassortant virus of swine origin, highlighted the importance of worldwide influenza virus surveillance in swine. To date, large-scale surveillance studies have been reported for southern China and North America, but such data have not yet been described for Europe. We report the first large-scale genomic characterization of 290 swine influenza viruses collected from 14 European countries between 2009 and 2013. A total of 23 distinct genotypes were identified, with the 7 most common comprising 82% of the incidence. Contrasting epidemiological dynamics were observed for two of these genotypes, H1huN2 and H3N2, with the former showing multiple long-lived geographically isolated lineages, while the latter had short-lived geographically diffuse lineages. At least 32 human-swine transmission events have resulted in A(H1N1)pdm09 becoming established at a mean frequency of 8% across European countries. Notably, swine in the United Kingdom have largely had a replacement of the endemic Eurasian avian virus-like ("avian-like") genotypes with A(H1N1)pdm09-derived genotypes. The high number of reassortant genotypes observed in European swine, combined with the identification of a genotype similar to the A(H3N2)v genotype in North America, underlines the importance of continued swine surveillance in Europe for the purposes of maintaining public health. This report further reveals that the emergences and drivers of virus evolution in swine differ at the global level.ImportanceThe influenza A(H1N1)pdm09 virus contains a reassortant genome with segments derived from separate virus lineages that evolved in different regions of the world. In particular, its neuraminidase and matrix segments were derived from the Eurasian avian virus-like ("avian-like") lineage that emerged in European swine in the 1970s. However, while large-scale genomic characterization of swine has been reported for southern China and North America, no equivalent study has yet been reported for Europe. Surveillance of swine herds across Europe between 2009 and 2013 revealed that the A(H1N1)pdm09 virus is established in European swine, increasing the number of circulating lineages in the region and increasing the possibility of the emergence of a genotype with human pandemic potential. It also has implications for veterinary health, making prevention through vaccination more challenging. The identification of a genotype similar to the A(H3N2)v genotype, causing zoonoses at North American agricultural fairs, underlines the importance of continued genomic characterization in European swine.

Project description:In June 2009, the World Health Organization declared the first influenza pandemic of the 21st century, due to the emergence and rapid spread of new swine origin H1N1 influenza A virus. In contrast to seasonal influenza infections, which typically cause morbidity and mortality in the elderly, this virus caused severe infection in young adults and not the elderly. This phenomenon was attributed to the presence of cross-neutralizing antibodies acquired by older individuals from previous exposure to swine origin influenza. However, this hypothesis could not be empirically tested using clinical data. To address this question, we investigated viral replication and the development of the immune response in naï12 years old) and aged (20 to 24 years old) female rhesus macaques infected with A/California/04/2009 (H1N1), one of the circulating pandemic strains in 2009. We compared viral loads as well as the kinetics and magnitude of the adaptive immune response in peripheral blood and bronchoalveolar lavage samples (BAL) collected longitudinally for 99 days post-infection. Although, adult animals exhibited earlier T cell responses in peripheral blood, aged animals generated a robust T cell response with comparable kinetics and magnitude as those observed in young animals in BAL. Moreover, aged animals generated a higher hemagglutination inhibition titer compared to young animals. We also measured the concentration of several cytokines in BAL supernatant. With the exception of IL-8, which was higher in aged animals, we found no differences in IFNa, IFNb, TNFa, IL-1r, IL-6, IL-15, IL-17, or MCP1 levels. Finally, we compared gene expression infection using microarray analysis of BAL samples taken on days 0, 4, 7, 10, and 14 pi. Our analyses revealed that the largest difference in host response between aged and young animals was detected day 4 post-infection, with significant enrichment for genes associated with inflammation, the innate immune response, and T cell activation in aged animals. The ability of aged animals to generate a robust immune response, especially antibody response, following infection with 2009 H1N1 virus could explain the lack of morbidity normally observed with seasonal influenza viruses in this vulnerable population. 16 female rhesus macaques (Macaca Mulatta) 10-12 (Adult) and 20-24 years (Old/Aged) of age were used in these studies. Animals were infected with A/California/04/ 2009 H1N1 using a combinatory of intra-tracheal (4ml), intranasal (0.5 ml/nostril), and conjunctival (0.5 ml/eyelid) routes for a total dose of 7x106 TCID50 dose. Microarray analysis was performed on Bronchoalveolar lavage (BAL) samples collected on days 0, 4, 7, 10 and 14. Note: One of the Day 0 array did not pass QC metrics so for this animal the average of the other Day 0 samples from that group was utilized. At the end of the study animals were released back to the colony.

Dataset Information

Molecular epidemiology of novel swine origin influenza virus (S-OIV) from Gwalior, India, 2009.

Publications

Molecular epidemiology of novel swine origin influenza virus (S-OIV) from Gwalior, India, 2009.

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