Browsing by Author "Neira, Victor"

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    Antigenic characterization of novel H1 influenza A viruses in swine
    (2020) Tapia, Rodrigo; Torremorell, Montserrat; Culhane, Marie; Medina, Rafael A.; Neira, Victor
    Novel H1N2 influenza A viruses (IAVs) in swine have been identified in Chile co-circulating with pandemic H1N1 2009-like (A(H1N1)pdm09-like) viruses. The objective of this study was to characterize antigenically the swine H1 IAVs circulating in Chile. Genetic analysis based on the HA1 domain and antigenic analysis by hemagglutination inhibition assay were carried out. Three antigenic clusters were identified, named Chilean H1 A (ChH1A), Chilean H1 B (ChH1B), and A(H1N1)pdm09-like. The antigenic sites of ChH1A and ChH1B strains were 10-60% distant from those of commercial vaccine strains at the amino acid sequence level. Antigenic variants were identified within the clusters ChH1A and A(H1N1)pdm09-like. Substitutions in the main antigenic sites (E153G in Sa, Q193H in Sb, D168N in Ca1, P137S in Ca2, and F71L in Cb) were detected in variants from the ChH1A cluster, whereas only a single substitution in antigenic site Sa (G155E) was detected in variants from A(H1N1)pdm09-like cluster, which confirms the importance to carrying out antigenic analyses in addition to genetic analyses to evaluate control measures such as vaccination. These results highlight the need to update vaccines for swine in Chile and the importance of continued surveillance to determine the onward transmission of antigenic variants in Chilean pig populations.
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    Avian orthoavulavirus 1 (Newcastle Disease virus) antibodies in five penguin species, Antarctic peninsula and Southern Patagonia
    (2021) Ariyama, Naomi; Tapia, Rodrigo; Godoy, Claudia; Aguero, Belen; Valdes, Valentina; Berrios, Felipe; Garcia Borboroglu, Pablo; Putz, Klemens; Alegria, Raul; Barriga, Gonzalo P.; Medina, Rafael; Neira, Victor
    Avian orthoavulavirus 1 (AOaV-1) causes Newcastle disease, one of the most important and contagious infections in poultry, where migratory birds can play a key role as a reservoir. Seven hundred and seven serum samples were collected from five penguin species (King, Magellanic, Gentoo, Chinstrap and Adelie penguins) in the Antarctic and Sub-Antarctic zones. Using a competitive ELISA to detect antibodies against AOaV-1, we identified positive individuals in all penguin species. The Magellanic penguin showed the highest seropositivity rate (30.3%), suggesting it could be a natural reservoir of this virus. At the Antarctic zones, Chinstrap penguin showed the highest occurrence (7.5%). Interesting, positive sera was only obtained in Sub-Antarctic and Northern zones at the Antarctic peninsula, no seroreactivity was observed in Southern locations. Further studies are needed to establish the role of these penguin species in the epidemiology of the AOaV-1 and determine the effects of this virus in these populations.
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    Circulation patterns of human seasonal Influenza A viruses in Chile before H1N1pdm09 pandemic
    (2021) Mena, Juan; Tapia, Rodrigo; Verdugo, Claudio; Avendano, Luis; Parra-Castro, Paulina; Medina, Rafael A.; Barriga, Gonzalo; Neira, Victor
    Understanding the diversity and circulation dynamics of seasonal influenza viruses is key to public health decision-making. The limited genetic information of pre-pandemic seasonal IAVs in Chile has made it difficult to accurately reconstruct the phylogenetic relationships of these viruses within the country. The objective of this study was to determine the genetic diversity of pre-pandemic human seasonal IAVs in Chile. We sequenced the complete genome of 42 historic IAV obtained between 1996 and 2007. The phylogeny was determined using HA sequences and complemented using other segments. Time-scale phylogenetic analyses revealed that the diversity of pre-pandemic human seasonal IAVs in Chile was influenced by continuous introductions of new A/H1N1 and A/H3N2 lineages and constant viral exchange between Chile and other countries every year. These results provide important knowledge about genetic diversity and evolutionary patterns of pre-pandemic human seasonal IAVs in Chile, which can help design optimal surveillance systems and prevention strategies. However, future studies with current sequences should be conducted.
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    Cross-protection of commercial vaccines against Chilean swine influenza A virus using the guinea pig model as a surrogate
    (2023) Tapia, Rodrigo; Mena, Juan; Garcia, Victoria; Culhane, Marie; Medina, Rafael A.; Neira, Victor
    Influenza A virus poses a significant threat to public health and the swine industry. Vaccination is the primary measure for controlling the disease, but the effectiveness of vaccines can vary depending on the antigenic match between vaccine strains and circulating strains. In Chile, H1N1pdm09 and other lineages H1N2 and H3N2 have been detected in pigs, which are genetically distinct from the strains included in commercial vaccines. This study aimed to evaluate the cross-protection by commercial vaccines against strains circulating in Chile using the guinea pig model. For this study, four circulating strains [A/swine/Chile/H1A-7/2014(H1N2), A/swine/Chile/H1B-2/2014(H1N2), A/swine/Chile/H1P-12/2015(H1N1), and A/swine/Chile/H3-2/2015(H3N2)] were selected. Guinea pigs were divided into vaccinated and control groups. The vaccinated animals received either a multivalent antigenically heterologous or monovalent homologous vaccine, while the control animals remained unvaccinated. Following vaccination, all animals were intranasally challenged, and nasal wash samples were collected at different time points post-infection. The results showed that the homologous monovalent vaccine-induced hemagglutinin-specific antibodies against the Chilean pandemic H1N1pdm09 strain. However, the commercial heterologous multivalent vaccine failed to induce hemagglutinin-specific antibody titers against the H1N2 and H3N2 challenge strains. Furthermore, the homologous monovalent vaccine significantly reduced the duration of viral shedding and viral titers specifically against the Chilean pandemic H1N1pdm09 strain and heterologous multivalent vaccine only partial. These findings highlight the importance of regularly updating vaccine strains to match the circulating field strains for effective control of swine influenza. Further research is needed to develop vaccines that confer broader protection against diverse strains of swine influenza A virus.
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    Emergence and rapid dissemination of highly pathogenic avian influenza virus H5N1 clade 2.3.4.4b in wild birds, Chile.
    (SPRINGER INTERNATIONAL PUBLISHING AG, 2023) Ariyama, Naomi; Pardo-Roa, Catalina; Munoz, Gabriela; Aguayo, Carolina; Avila, Claudia; Mathieu, Christian; Brito, Barbara; Medina, Rafael; Johow, Magdalena; Neira, Victor
    In December 2022, HPAI H5N1 clade 2.3.4.4b emerged in Chile. We detected the virus in 93 wild bird samples and sequenced the whole genome of nine Chilean strains from pelicans and gulls. Phylogenetic analysis suggests at least two different HPAI viral clusters in South America.
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    Mass mortality event in South American sea lions (Otaria flavescens) correlated to highly pathogenic avian influenza (HPAI) H5N1 outbreak in Chile
    (2023) Ulloa, Mauricio; Fernandez, Antonio; Ariyama, Naomi; Colom-Rivero, Ana; Rivera, Carlos; Nunez, Paula; Sanhueza, Paola; Johow, Magdalena; Araya, Hugo; Torres, Juan Carlos; Gomez, Paola; Munoz, Gabriela; Aguero, Belen; Alegria, Raul; Medina, Rafael; Neira, Victor; Sierra, Eva
    In Chile, since January 2023, a sudden and pronounced increase in strandings and mortality has been observed among South American (SA) sea lions (Otaria flavescens), prompting significant concern. Simultaneously, an outbreak of highly pathogenic avian influenza H5N1 (HPAIV H5N1) in avian species has emerged since December 2022. To investigate the cause of this unexpected mortality, we conducted a comprehensive epidemiological and pathologic study. One hundred sixty-nine SA sea lions were sampled to ascertain their HPAIV H5N1 status, and long-term stranding trends from 2009 to 2023 were analyzed. In addition, two animals were necropsied. Remarkably, a significant surge in SA sea lion strandings was observed initiating in January 2023 and peaking in June 2023, with a count of 4,545 stranded and deceased animals. Notably, this surge in mortality correlates geographically with HPAIV outbreaks affecting wild birds. Among 168 sampled SA sea lions, 34 (20%) tested positive for Influenza A virus, and 21 confirmed for HPAIV H5N1 2.3.4.4b clade in tracheal/rectal swab pools. Clinical and pathological evaluations of the two necropsied stranded sea lions revealed prevalent neurological and respiratory signs, including disorientation, tremors, ataxia, and paralysis, as well as acute dyspnea, tachypnea, profuse nasal secretion, and abdominal breathing. The lesions identified in necropsied animals aligned with observed clinical signs. Detection of the virus via immunohistochemistry (IHC) and real-time PCR in the brain and lungs affirmed the findings. The findings provide evidence between the mass mortality occurrences in SA sea lions and HPAIV, strongly indicating a causal relationship. Further studies are needed to better understand the pathogenesis and transmission.
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    Novel influenza A viruses in pigs with zoonotic potential, Chile
    (2024) Tapia, Rodrigo; Brito, Barbara; Saavedra, Marco; Mena, Juan; Garcia-Salum, Tamara; Rathnasinghe, Raveen; Barriga, Gonzalo; Tapia, Karla; Garcia, Victoria; Bucarey, Sergio; Jang, Yunho; Wentworth, David; Torremorell, Montserrat; Neira, Victor; Medina, Rafael A.
    Novel H1N2 and H3N2 swine influenza A viruses (IAVs) have recently been identified in Chile. The objective of this study was to evaluate their zoonotic potential. We perform phylogenetic analyses to determine the genetic origin and evolution of these viruses, and a serological analysis to determine the level of cross-protective antibodies in the human population. Eight genotypes were identified, all with pandemic H1N1 2009-like internal genes. H1N1 and H1N2 were the subtypes more commonly detected. Swine H1N2 and H3N2 IAVs had hemagglutinin and neuraminidase lineages genetically divergent from IAVs reported worldwide, including human vaccine strains. These genes originated from human seasonal viruses were introduced into the swine population since the mid-1980s. Serological data indicate that the general population is susceptible to the H3N2 virus and that elderly and young children also lack protective antibodies against the H1N2 strains, suggesting that these viruses could be potential zoonotic threats. Continuous IAV surveillance and monitoring of the swine and human populations is strongly recommended.IMPORTANCEIn the global context, where swine serve as crucial intermediate hosts for influenza A viruses (IAVs), this study addresses the pressing concern of the zoonotic potential of novel reassortant strains. Conducted on a large scale in Chile, it presents a comprehensive account of swine influenza A virus diversity, covering 93.8% of the country's industrialized swine farms. The findings reveal eight distinct swine IAV genotypes, all carrying a complete internal gene cassette of pandemic H1N1 2009 origin, emphasizing potential increased replication and transmission fitness. Genetic divergence of H1N2 and H3N2 IAVs from globally reported strains raises alarms, with evidence suggesting introductions from human seasonal viruses since the mid-1980s. A detailed serological analysis underscores the zoonotic threat, indicating susceptibility in the general population to swine H3N2 and a lack of protective antibodies in vulnerable demographics. These data highlight the importance of continuous surveillance, providing crucial insights for global health organizations.
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    Replication kinetics of novel swine influenza A viruses: an approach to vaccine production
    (2024) Tapia, Rodrigo; Medina, Rafael; Neira, Victor
    Novel swine Influenza A viruses (IAVs) have been described in South America. The objective of this study was to evaluate the replication kinetics of novel swine IAVs as a first step in vaccine production. Different swine IAV lineages (H1N1, H1N2, and H3N2), infection doses (MOI: 1, 0.1, 0.01, 0.001, 0.0001, and 0.00001), harvest times (every 12 h), and substrates (MDCK and Vero cells) were used. For all IAV strains, MDCK cells were the most efficient substrate, generating titers of >= 128 HAU/50 mu L with an MOI of 0.00001 at 60 h post-infection. These data may be useful in vaccine- producing laboratories.
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    Ubiquitous influenza A virus in Chilean swine before the H1N1pdm09 introduction
    (2021) Mena, Juan; Ariyama, Naomi; Navarro, Camila; Quezada, Manuel; Brevis, Cristina; Rojas, Daniela; Medina, Rafael A.; Brito, Barbara; Ruiz, Alvaro; Neira, Victor
    Influenza A virus (IAV) was a neglected swine pathogen in South America before the 2009 H1N1 pandemic (A(H1N1)pdm2009). The A(H1N1)pdm2009 strain has widely spread among the Chilean swine population and co-circulates with endemic H1N2 and H3N2 viruses. The presence of IAV as a swine pathogen in Chilean swine before the 2009 pandemic is unknown. To understand the IAV in swine prior to 2009, aY retrospective study of samples from pigs affected with respiratory diseases was conducted. Ninety formalin-fixed and paraffin-embedded lung tissues belonging to 21 intensive pig production companies located in five different administrative regions of Chile, collected between 2005 and 2008, were evaluated. The tissues were tested by immunohistochemistry (IHC), identifying that 9 out of 21 farms (42.8%) and 31 out of 90 (34.4%) samples were IAV positive. Only three out of the 31 IHC-positive samples were positive upon RNA extraction and rtRT-PCR analysis. Partial nucleotide sequences were obtained from one sample and characterized as an H3N2 subtype closely related to a human seasonal H3N2 IAVs that circulated globally in the mid-90s. These results indicate that IAV was circulating in swine before 2009 and highlight the value of conducting retrospective studies through genomic strategies to analyse historical samples.