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H9N2 avian influenza is a low-pathogenic avian influenza circulating in poultry and wild birds worldwide and frequently contributes to chicken salpingitis that is caused by avian pathogenic Escherichia coli (APEC), leading to huge economic losses and risks for food safety. Currently, how the H9N2 virus contributes to APEC infection and facilitates salpingitis remains elusive. In this study, in vitro chicken oviduct epithelial cell (COEC) model and in vivo studies were performed to investigate the role of H9N2 viruses on secondary APEC infection, and we identified that H9N2 virus enhances APEC infection both in vitro and in vivo . To understand the mechanisms behind this phenomenon, adhesive molecules on the cell surface facilitating APEC adhesion were checked, and we found that H9N2 virus could upregulate the expression of fibronectin, which promotes APEC adhesion onto COECs. We further investigated how fibronectin expression is regulated by H9N2 virus infection and revealed that transforming growth factor beta (TGF-β) signaling pathway is activated by the NS1 protein of the virus, thus regulating the expression of adhesive molecules. These new findings revealed the role of H9N2 virus in salpingitis co-infected with APEC and discovered the molecular mechanisms by which the H9N2 virus facilitates APEC infection, offering new insights to the etiology of salpingitis with viral-bacterial co-infections.IMPORTANCEH9N2 avian influenza virus (AIV) widely infects poultry and is sporadically reported in human infections. The infection in birds frequently causes secondary bacterial infections, resulting in severe symptoms like pneumonia and salpingitis. Currently, the mechanism that influenza A virus contributes to secondary bacterial infection remains elusive. Here we discovered that H9N2 virus infection promotes APEC infection and further explored the underlying molecular mechanisms. We found that fibronectin protein on the cell surface is vital for APEC adhesion and also showed that H9N2 viral protein NS1 increased the expression of fibronectin by activating the TGF-β signaling pathway. Our findings offer new information on how AIV infection promotes APEC secondary infection, providing potential targets for mitigating severe APEC infections induced by H9N2 avian influenza, and also give new insights on the mechanisms on how viruses promote secondary bacterial infections in animal and human diseases., Competing Interests: The authors declare no conflict of interest.

The avian pathogen Mycoplasma gallisepticum , the etiological agent of chronic respiratory disease in chickens, exhibits enhanced pathogenesis in the presence of a copathogen such as low-pathogenic avian influenza virus (LPAIV). To further investigate the intricacies of this copathogenesis, chickens were monoinfected or coinfected with either virulent M. gallisepticum strain R low or LPAIV H3N8 (A/duck/Ukraine/1963), with assessment of tracheal histopathology, pathogen load, and transcriptomic host responses to infection by RNA sequencing. Chickens coinfected with M. gallisepticum R low followed by LPAIV H3N8 exhibited significantly more severe tracheal lesions and mucosal thickening than chickens infected with LPAIV H3N8 alone and greater viral loads than chickens infected first with H3N8 and subsequently with M. gallisepticum R low Recovery of live M. gallisepticum was significantly higher in chickens infected first with LPAIV H3N8 and then with M. gallisepticum R low , compared to chickens given a mock infection followed by M. gallisepticum R low The transcriptional responses to monoinfection and coinfection with M. gallisepticum and LPAIV highlighted the involvement of differential expression of genes such as Toll-like receptor 15, Toll-like receptor 21, and matrix metallopeptidase 1. Pathway and gene ontology analyses of these differentially expressed genes suggest that coinfection with virulent M. gallisepticum and LPAIV induces decreases in the expression of genes related to ciliary activity in vivo and alters multiple immune-related signaling cascades. These data aid in the understanding of the relationship between M. gallisepticum and LPAIV during copathogenesis in the natural host and may contribute to further understanding of copathogen infections of humans and other animals., (Copyright © 2019 American Society for Microbiology.)

Since 2007, most areas of China have seen outbreaks of poultry airsacculitis, which causes hugely economic losses to the poultry industry. However, there are no effective measures to combat the problem. In this study, 105 rations were collected to isolate Aspergillus spp. from the diseased farms. In subsequent experiments, SPF chickens were inoculated with Ornithobacterium rhinotracheale (ORT), Chlamydia psittaci (C. psittaci) and Aspergillus fumigatus (A. fumigatus), and mortality rate, body weight gain and lesion score were evaluated. Of these ration samples, 63 (60.0%) were A. fumigates, 21 (20.0%) were Aspergillus niger (A. niger) and 11 (10.5%) were Aspergillus candidus (A. candidus). Furthermore, SPF birds infected with C. psittaci, ORT, H9N2 virus and A. fumigatus conidia exhibited a mortality rate of 40%, while simultaneous co-infection with C. psittaci, ORT and A. fumigatus resulted in a mortality rate of 20%. The avian airsacculitis was manifested in the C. psittaci + ORT/A. fumigatus, C. psittaci + H9N2 + ORT/A. fumigatus and C. psittaci + H9N2/A. fumigatus groups while others had transient respiratory diseases without mortality. Our survey indicates that feed-borne A. fumigatus is prevalent in poultry rations. The combination of C. psittaci, ORT, H9N2 and A. fumigatus conidia contributes to the replication of avian airsacculitis by aggravating the severe damage to the air sacs and lungs of chickens.

In Egypt, currently two geographically restricted genotypes of the infectious bronchitis coronavirus (IBV) are circulating with detrimental effects for poultry industry. A sensitive real-time RT-PCR assay targeting the IBV nucleocapsid gene (N) was developed to screen clinical samples for presence of IBV. Conventional RT-PCRs amplifying hypervariable regions (HVRs 1-2 and 3) of the IBV S1 gene were developed and amplificates used for nucleotide sequence-based typing of IBV field strains in Egyptian chickens directly from clinical samples., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Emerging pathogenic viruses such as Ebola and Middle Eastern Respiratory Syndrome coronavirus (MERS-CoV) can cause acute infections through the evasion of the host's antiviral immune responses and by inducing the upregulation of inflammatory cytokines. This immune dysregulation, termed a cytokine storm or hypercytokinemia, is potentially fatal and is a significant underlying factor in increased mortality of infected patients. The prevalence of global outbreaks in recent years has offered opportunities to study the progression of various viral infections and have provided an improved understanding of hypercytokinemia associated with these diseases. However, despite this increased knowledge and the study of the infections caused by a range of emerging viruses, the therapeutic options still remain limited. This review aims to explore alternative experimental strategies for treating hypercytokinemia induced by the Ebola, avian influenza and Dengue viruses; outlining their modes of action, summarizing their preclinical assessments and potential clinical applications.

Background: Indonesia has the highest human mortality from highly pathogenic avian influenza (HPAI) A (H5N1) virus infection in the world., Methods: A survey of households (N=2520) measured treatment sources and beliefs among symptomatic household members. A survey of physicians (N=554) in various types of health care facilities measured knowledge, assessment and testing behaviors, and perceived clinical capacity., Results: Households reported confidence in health care system capacity but infrequently sought treatment for potential HPAI H5N1 signs/symptoms. More clinicians were confident in their knowledge of diagnosis and treatment than in the adequacy of related equipment and resources at their facilities. Physicians expressed awareness of the HPAI H5N1 suspect case definition, yet expressed only moderate knowledge in questioning symptomatic patients about exposures. Self-reported likelihood of testing for HPAI H5N1 virus was high after learning of certain exposures. Knowledge of antiviral treatment was moderate, but it was higher among clinicians in puskesmas. Physicians in private outpatient clinics, the most heavily used facilities, reported the lowest confidence in their diagnostic and treatment capabilities., Conclusions: Educational campaigns can encourage recall of possible poultry exposure when patients are experiencing signs/symptoms and can raise awareness of the effectiveness of antivirals to drive people to seek health care. Clinicians may benefit from training regarding exposure assessment and referral procedures, particularly in private clinics. (Disaster Med Public Health Preparedness. 2016;10:838-847).

Avian influenza virus subtype H9N2 (H9N2) and Chlamydia psittaci (C. psittaci) are frequently isolated in chickens with respiratory disease. However, their roles in co-infection remain unclear. We tested the hypothesis that C. psittaci enhances H9N2 infection through suppression of host immunity. Thus, 10-day-old SPF chickens were inoculated intra-tracheally with a high or low virulence C. psittaci strain, and were simultaneously vaccinated against Newcastle disease virus (NDV). Significant decreases in body weight, NDV antibodies and immune organ indices occurred in birds with the virulent C. psittaci infection, while the ratio of CD4+/CD8+ T cells increased significantly compared to that of the lower virulence strain. A second group of birds were inoculated with C. psittaci and H9N2 simultaneously (C. psittaci+H9N2), C. psittaci 3 days prior to H9N2 (C. psittaci/H9N2), or 3 days after H9N2 (H9N2/C. psittaci), C. psittaci or H9N2 alone. Survival rates were 65%, 80% and 90% in the C. psittaci/H9N2, C. psittaci+H9N2 and H9N2/C. psittaci groups, respectively and respiratory clinical signs, lower expression of pro-inflammatory cytokines and higher pathogen loads were found in both C. psittaci/H9N2 and C. psittaci+H9N2 groups. Hence, virulent C. psittaci infection suppresses immune response by inhibiting humoral responses and altering Th1/Th2 balance, increasing mortality in H9N2 infected birds.

Background: The epidemiology of avian hematozoa at high latitudes is still not well understood, particularly in sub-Arctic and Arctic habitats, where information is limited regarding seasonality and range of transmission, co-infection dynamics with parasitic and viral agents, and possible fitness consequences of infection. Such information is important as climate warming may lead to northward expansion of hematozoa with unknown consequences to northern-breeding avian taxa, particularly populations that may be previously unexposed to blood parasites., Methods: We used molecular methods to screen blood samples and cloacal/oropharyngeal swabs collected from 1347 ducks of five species during May-August 2010, in interior Alaska, for the presence of hematozoa, Influenza A Virus (IAV), and IAV antibodies. Using models to account for imperfect detection of parasites, we estimated seasonal variation in prevalence of three parasite genera (Haemoproteus, Plasmodium, Leucocytozoon) and investigated how co-infection with parasites and viruses were related to the probability of infection., Results: We detected parasites from each hematozoan genus in adult and juvenile ducks of all species sampled. Seasonal patterns in detection and prevalence varied by parasite genus and species, age, and sex of duck hosts. The probabilities of infection for Haemoproteus and Leucocytozoon parasites were strongly positively correlated, but hematozoa infection was not correlated with IAV infection or serostatus. The probability of Haemoproteus infection was negatively related to body condition in juvenile ducks; relationships between Leucocytozoon infection and body condition varied among host species., Conclusions: We present prevalence estimates for Haemoproteus, Leucocytozoon, and Plasmodium infections in waterfowl at the interface of the sub-Arctic and Arctic and provide evidence for local transmission of all three parasite genera. Variation in prevalence and molecular detection of hematozoa parasites in wild ducks is influenced by seasonal timing and a number of host traits. A positive correlation in co-infection of Leucocytozoon and Haemoproteus suggests that infection probability by parasites in one or both genera is enhanced by infection with the other, or that encounter rates of hosts and genus-specific vectors are correlated. Using size-adjusted mass as an index of host condition, we did not find evidence for strong deleterious consequences of hematozoa infection in wild ducks.

Background: A 2006 avian influenza (AI) outbreak resulted in mass removal of chickens in Lower Egypt, which decreased the household supply of poultry. Poultry, a key animal-source food, contains nutrients critical for child growth. This paper examines determinants of stunting between 2006 and 2008 in children 6 to 59 months of age within the context of the AI outbreak., Methods: The 2005 and 2008 nationally representative Egypt Demographic and Health Surveys (EDHS) were used to analyse anthropometric data from 7,794 children in 2005 and 6,091 children in 2008. Children, 6-59 months of age, with length for age Z-score < -2 S.D. were categorized as stunted. Predictors of stunting were examined by bivariate and multivariable analyses, focusing on Lower Egypt, where a rise in stunting occurred, and Upper Egypt, where stunting declined., Results: Between 2005 and 2008, Upper Egypt experienced a significant decline in stunting (28.8 to 21.8%, P < 0.001). Lower Egypt experienced a significant rise in stunting (16.6 to 31.5%, P < 0.001), coinciding with the 2006 AI outbreak. In Lower Egypt (2008), households owning poultry were 41.7% less likely to have a stunted child [aOR 0.58; 95% CI (0.42, 0.81) P = 0.002], and 12-47 month old children were 2.12-2.34 times [95% CI (1.39 - 3.63) P ≤ 0.001] more likely to be stunted than 6-11 month old children. Older children were likely affected by AI, as these children were either in-utero or toddlers in 2006. In Upper Egypt, stunting peaked at 12-23 months [aOR 2.62, 95% CI (1.73-3.96), P < 0.001], with lowered risk (22-32%) of stunting in 24-47 month old children [aOR1.65, 95% 1.07-2.53, P = 0.022, 24-35 month old] and [aOR 1.57, 95% CI 1.01-2.43, P = 0.043 36-47 months old]. A two-fold increase in child consumption of sugary foods between 2005 and 2008 was found in Lower Egypt (24.5% versus 52.7%; P < .001)., Conclusions: Decreased dietary diversity, reduced poultry consumption, substitution of nutritious foods with sugary foods paralleled a reduction in household raising of birds, following the AI outbreak in Lower Egypt and not Upper Egypt. Increased feeding of sugary foods due to fear of illness or greater penetration of these foods may be related to stunting. Advice on infant and young child feeding is needed to improve dietary intake and reduce sugary food consumption.

Saliva proteins may protect older people from influenza, however, it is often noted that hospitalizations and deaths after an influenza infection mainly occur in the elderly population living with chronic diseases, such as diabetes and cancer. Our objective was to investigate the expression level of the terminal α2-3- and α2-6-linked sialic acids in human saliva from type 2 diabetes mellitus (T2DM), liver disease and gastric cancer (GC) patients and assess the binding activity of these linked sialic acids against influenza A viruses (IAV). We observed that the expression level of the terminal α2-3-linked sialic acids of elderly individuals with T2DM and liver disease were down-regulated significantly, and the terminal α2-6 linked sialic acids were up-regulated slightly or had no significant alteration. However, in the saliva of patients with GC, neither sialic acid was significantly altered. These findings may reveal that elderly individuals with chronic diseases, such as diabetes and liver disease, might be more susceptible to the avian influenza virus due to the decreased expression of terminal α2-3-linked sialic acids in their saliva.

Raptors may contract highly pathogenic avian influenza virus H5N1 by hunting or scavenging infected prey. However, natural H5N1 infection in raptors is rarely reported. Therefore, we tested raptors found dead during an H5N1 outbreak in wild waterbirds in Mecklenburg-Western Pomerania, Germany, in 2006 for H5N1-associated disease. We tested 624 raptors of nine species-common buzzard (385), Eurasian sparrowhawk (111), common kestrel (38), undetermined species of buzzard (36), white-tailed sea eagle (19), undetermined species of raptor (12), northern goshawk (10), peregrine falcon (6), red kite (3), rough-legged buzzard (3), and western marsh-harrier (1)-for H5N1 infection in tracheal or combined tracheal/cloacal swabs of all birds, and on major tissues of all white-tailed sea eagles. H5N1 infection was detected in two species: common buzzard (12 positive, 3.1%) and peregrine falcon (2 positive, 33.3%). In all necropsied birds (both peregrine falcons and the six freshest common buzzards), H5N1 was found most consistently and at the highest concentration in the brain, and the main H5N1-associated lesion was marked non-suppurative encephalitis. Other H5N1-associated lesions occurred in air sac, lung, oviduct, heart, pancreas, coelomic ganglion, and adrenal gland. Our results show that the main cause of death in H5N1-positive raptors was encephalitis. Our results imply that H5N1 outbreaks in wild waterbirds are more likely to lead to exposure to and mortality from H5N1 in raptors that hunt or scavenge medium-sized birds, such as common buzzards and peregrine falcons, than in raptors that hunt small birds and do not scavenge, such as Eurasian sparrowhawks and common kestrels.

Clinical signs such as respiratory signs, egg drop, and mortality have been reported in field cases of low pathogenic avian influenza by H9N2 avian influenza virus (AIV) but have rarely been reproduced by the virus alone. Thus, virus reisolation rates and titers in tissues were measured for vaccine efficacy testing. In the present study, we established a clinical sign-based vaccine efficacy test by reproduction of highly frequent conjunctivitis (77.8%-90%) via binocular instillation of an H9N2 virus (01310) strain, 1 x 10(6) EID50/10 microl for each eye). Specific-pathogen-free chickens were assigned to vaccine and control groups, and the vaccine group was inoculated intramuscularly with a commercial H9N2 inactivated oil emulsion vaccine. The chickens were challenged by 01310 via binocular instillation at 2 and 4 wk postvaccination (WPV). The positive rates of conjunctivitis and virus reisolation were significantly different between the vaccine and control groups (conjunctivitis at 2 WPV, 0% vs. 77.8%, and at 4 WPV, 0% vs. 80%). Vaccine antibody was detected in tears as well as in serum samples of the vaccine group before challenge. The conjunctivitis model may be useful for efficacy testing of AI vaccine due to a clinical symptom-based read of results, but further efficacy testings with different types, doses of AI vaccines, and challenge viruses will be required to complete the evaluation of our model.

Influenza viruses from domestic aquatic birds can be transmitted to chickens, resulting in continued prevalence of the disease. H3 viruses are one of the most frequently identified subtypes in domestic ducks. Results from our previous serologic study suggested that H3 virus infections potentially exist in chickens with a wide geographical distribution in China. To better understand their pathogenic potential, two H3N8 influenza viruses isolated from domestic ducks were selected for experimental infections in chickens. We found that viral shedding lasted for at least 14 days postinfection for both viruses; however, one virus caused mortality in the chickens when coinfected with Escherichia coli. Sequencing of the viral HA gene isolated from the inoculated chickens revealed two amino acid mutations within the gene. These findings demonstrate the pathogenicity of the H3N8 domestic duck influenza viruses to chickens, highlighting the need for routine epidemiologic investigations of H3 subtype influenza viruses in chicken populations.

Background: Since 2008, a progressive pneumonia has become prevalent in broilers and laying hens. This disease occurrs the first day after hatching and lasts more than 30 days, resulting in approximately 70% morbidity and 30% mortality in broilers. The objective of this study was to isolate and identify the pathogens that are responsible for the progressive pneumonia and establish an animal model for drug screening., Results: 193 serum samples were collected from 8 intensive farms from 5 provinces in China and analysed in the current research. Our clinical survey showed that 65.2% to 100% of breeding broilers, breeding layers, broilers and laying hens were seropositive for ORT antibodies. From 8 intensive farms, six ORT isolates were identified by PCR and biochemical assays, and two H9N2 viruses were isolated. Newcastle Disease Virus (NDV) and Infectious BronchitisVirus (IBV) were excluded. Typical pneumonia and airsacculitis were observed both in broilers inoculated intraperitoneally with an ORT isolate alone and in those co-infected with ORT and H9N2 virus isolates. Specifically, the survival rate was 30%, 20%, 70%, 50% and 90% in birds inoculated with ORT+H9N2 virus, ORT followed by H9N2 virus, H9N2 virus followed by ORT, and ORT or H9N2 virus alone, respectively., Conclusions: The results of this study suggest that ORT infections of domestic poultry have been occurring frequently in China. ORT infection can induce higher economic losses and mortality if H9N2 AIV is also present. Although the isolation of ORT and H9N2 virus has been reported previously, there have been no reported co-infections of poultry with these two pathogens. This is the first report of co-infection of broilers with ORT and H9N2 virus, and this co-infection is probably associated with the outbreak of broiler airsacculitis in China, which has caused extensive economic losses.

During the outbreak of highly pathogenic avian influenza (HPAI) H5N1 in Sweden in 2006, disease and mortality were observed in a number of wild bird species. Encephalitis was one of the most consistent and severe findings in birds submitted for postmortem examination. However, the distribution and severity of the inflammation varied among individuals. This study characterized the encephalitis and the phenotype of the cellular infiltrate in brains of 40 birds of various species naturally infected with HPAI H5N1. Brain sections stained with hematoxylin and eosin and immunostained for influenza A viral antigen were evaluated in parallel to brain sections immunostained with antibodies against T lymphocytes (CD3+), B lymphocytes (CD79a+), macrophages (Lectin RCA-1+), and astrocytes expressing glial fibrillary acidic protein. The virus showed marked neurotropism, and the neuropathology included multifocal to diffuse areas of gliosis and inflammation in the gray matter, neuronal degeneration, neuronophagia, vacuolation of the neuropil, focal necrosis, perivascular cuffing, and meningitis. Broad ranges in severity, neuroanatomical distribution, and type of cellular infiltrate were observed among the different bird species. Since neurotropism is a key feature of HPAI H5N1 infection in birds and other species and because the clinical presentation can vary, the characterization of the inflammation in the brain is important in understanding the pathogenesis of the disease and also has important diagnostic implications for sample selection.

Chickens were infected under experimental conditions with Mycoplasma gallisepticum and low pathogenic avian influenza (LPAI) strain A/mallard/Hungary/19616/07 (H3N8). Two groups of chickens were aerosol challenged with M. gallisepticum strain 1226. Seven days later, one of these groups and one mycoplasma-free group was challenged with LPAI H3N8 virus; one group without challenge remained as negative control. Eight days later, the birds were euthanized and examined for gross pathologic and histologic lesions. The body weight was measured, and the presence of antimycoplasma and antiviral antibodies was tested before the mycoplasma challenge, before the virus challenge, and at the end of the study to confirm both infections. Chickens in the mycoplasma-infected group developed antibodies against M. gallisepticum but not against the influenza virus. Chickens of the group infected with the influenza virus became serologically positive only against the virus, while the birds in the coinfected group developed antibodies against both agents. The LPAI H3N8 virus strain did not cause decrease in body weight and clinical signs, and macroscopic pathological lesions were not present in the chickens. The M. gallisepticum infection caused respiratory signs, airsacculitis, and peritonitis characteristic of mycoplasma infection. However, the clinical signs and pathologic lesions and the reduction in weight gain were much more significant in the group challenged with both M. gallisepticum and LPAI H3N8 virus than in the group challenged with M. gallisepticum alone.

Introduction: The first H5N1 outbreak in Burkina Faso was reported to the World Organization for Animal Health on 3 April 2006. This study aimed to determine the prevalence of avian influenza virus, infectious bronchitis virus, and Newcastle disease virus among domestic and wild birds in highly pathogenic avian influenza (HPAI) H5N1 outbreaks areas., Methodology: We collected paired tracheal and cloacal swabs from 283 birds including 278 domestic and five wild birds (three vultures, one sparrowhawk and one Western Grey Plantain-eater) in the Central Region (Ouagadougou) and the Western Region (Bobo-Dioulasso and Sokoroni) of Burkina Faso. Total RNA extracted from samples were subjected to reverse transcription  and resulting cDNA amplified by PCR using specific primers for detection of Avian Influenza Virus (AIV mainly highly pathogenic H5N1), Infectious Bronchitis Virus (IBV), and Newcastle Disease Virus (NDV) for the first time in Burkina Faso., Results and Conclusions: Our results show that 13.8% (39/283) samples were reactive for NDV, and the prevalence of IBV was 3.9% (11/283). None of the 283 birds were co-infected by AIV, IBV and/or NDV in our study areas. The prevalence of influenza A virus was 3.2% (95% CI: 0-6.6) with a 1.7% (95% CI: 0-3.2) prevalence of H5N1 being detected. Positive cases of H5N1 virus were found in two out of three vultures in Ouagadougou, and in three out of 203 local chickens in the Western Region. These results confirm the presence of influenza A H5N1 virus, IBV and NDV in domestic and wild birds in Burkina Faso.

Avian influenza viruses (AIVs) are important zoonotic pathogens whose natural reservoir is waterfowl. In addition to AIV, waterfowl are often coinfected with other viruses, such as the paramyxoviruses, of which Newcastle disease virus (NDV) is of particular importance because of the highly virulent nature of certain strains of this virus for domestic poultry. In routine surveillance of waterfowl for AIV, a number of cloacal samples were encountered that were positive for AIV by real-time reverse transcription polymerase chain reaction (RT-PCR), but did not yield AIV by inoculation in embryonated chicken eggs. On further testing, these samples were also positive for NDV by conventional RT-PCR. It was hypothesized that if both NDV and AIV are present in a sample, the former may overgrow AIV yielding false-negative AIV results. Such samples were treated with chicken anti-NDV polyclonal antiserum and then inoculated in embryonated chicken eggs. Several samples were found to be positive for different subtypes of AIV, indicating that, in the presence of mixed infection with NDV and AIV, it is imperative to remove the influence of NDV, so a true picture of AIV prevalence emerges. An additional benefit is that information on the circulation of NDV in these birds sheds light on their epidemiologic and ecologic significance.

In the last century, humankind has faced 3 major pandemics of influenza virus infections. The first one occurred in 1918 and caused a significant amount of deaths. It was also capable of crossing over species barrier and affecting mammals, and most worrisome, humans. Since then several outbreaks have been reported in the Southeast of Asia. Many patients with the flu-like illness have a severe course and the patient develops pneumonia and in some cases multiorgan failure involving liver, kidneys, brain and lungs. Since the virus lacks regulatory control of genetic division it undergoes constant mutations leading to new subtypes and, sometimes, new strains. The only drugs that have shown some protection are oseltamivir and zanamivir. It is crucial to develop effective and non-expensive vaccines to prevent the virus spread and infection not only in humans but in birds too.

Avian influenza virus of H9N2 subtype is pathotyped as a non-highly pathogenic virus. However, frequent incidences of avian influenza of high mortality that are caused by H9N2 viruses have been observed in broiler chicken farms in Iran and some other Asian countries. Coinfections or environmental factors may be involved in such cases. Infectious microorganisms have been implicating in taking part in the cases of coinfection. We studied the effect of experimental coinfection of H9N2 avian influenza virus with infectious bronchitis live vaccine, which is used extensively in chicken farms in Iran. Clinical signs, gross lesions, viral shedding and mortality rate of the experimentally infected birds were examined. Coinfection of infectious bronchitis live vaccine and H9N2 avian influenza virus led to an extension of the shedding period of H9N2 virus, increasing the severity of clinical signs and mortality rates, causing macroscopic lesions in the embryos.

H5N1 avian influenza has been widely spreading in fowls in the Eastern Hemisphere and caused hundreds of severe human cases. Here, the information of the 224 human cases of H5N1 avian influenza reported by the World Health Organization before June 2006 were surveyed and analyzed. The results suggested that human infections escalated in the past 3 years, and control of animal H5N1 influenza, avoidance of high-risk behaviors, and proper disposal of diseased or dead fowls are vital for the prevention of the human infections. Age distribution of the human cases demonstrated that older people are more immune to the infection, possibly because of the cross protectivity induced by their previous infections with human influenza A viruses. This survey also suggested that live vaccines against human influenza may be of utility in the prevention of the avian influenza virus infections in humans, and new preventive measures should be considered for the control of animal H5N1 influenza epidemics, which are likely more serious than indicated by official reports.

Recent incidences of direct passage of highly pathogenic avian influenza A virus strains of the H5N1 and H7N7 subtypes from birds to man have become a major public concern. Although presence of virus in the human brain has not yet been reported in deceased patients, these avian influenza subtypes have the propensity to invade the brain along cranial nerves to target brainstem and diencephalic nuclei following intranasal instillation in mice and ferrets. The associations between influenza and psychiatric disturbances in past epidemics are here commented upon, and the potentials of influenza to cause nervous system dysfunction in experimental infections with a mouse-neuroadapted WSN/33 strain of the virus are reviewed. This virus strain is closely related to the Spanish flu virus, which is characterized as a uniquely high-virulence strain of the H1N1 subtype. The Spanish flu virus has recently been reconstructed in the laboratory and it passed once, most likely, directly from birds to humans to cause the severe 1918-1919 pandemic.

Severe hemorrhage at multiple organs is frequently observed in chickens infected with highly pathogenic avian influenza (HPAI) A viruses. In this study we examined whether HPAI virus infection leads to coagulation disorder in chickens. Pathological examinations showed that the fibrin thrombi were formed in arterioles at the lung, associated with the viral antigens in endothelial cells of chickens infected intravenously with HPAI virus. Hematological analyses of peripheral blood collected from the chickens revealed that coagulopathy was initiated at early stage of infection when viral antigens were detected only in the endothelial cells and monocytes/macrophages. Furthermore, gene expression of the tissue factor, the main initiator of blood coagulation, was upregulated in the spleen, lung, and brain of HPAI virus-infected chickens. These results suggest that dysfunction of endothelial cells and monocytes/macrophages upon HPAI virus infection may induce hemostasis abnormalities represented by the excessive blood coagulation and consumptive coagulopathy in chickens.

Avian influenza virus (AIV) of waterfowl origin, A/Mallard/Ohio/184/86 (H5N1), was used to evaluate the effect of AIV infection on the functional capabilities of the immune system in mallard ducks. The three main arms of the immune system--humoral, cell-mediated, and cellular--were evaluated. The integrity of the humoral immune system after AIV infection was evaluated by measuring total immunoglobulin and IgG antibody production to sheep erythrocytes and Brucella abortus antigen using hemagglutination and microagglutination assays, respectively. Cell-mediated immunity was evaluated using mitogen/antigen stimulation assays, and by measuring the cutaneous basophilic hypersensitivity response to intradermal phytohemagglutinin-P inoculation. The cellular component of the immune response was evaluated using whole-blood chemiluminescence and bacterial clearance assays. Results showed that infection with this AIV isolate suppressed T-cell function and enhanced macrophage phagocytic activity.

The effect of avian influenza virus (AIV) infection on the ability of turkeys to eliminate Pasteurella multocida from the respiratory tract was evaluated. Four-week-old turkeys were experimentally infected with an apathogenic AIV subtype (H5N2) by the oculonasal route and subsequently superinfected with P multocida (Urbach strain) by the intranasal route three days after infection with AIV. Quantitative clearance of P multocida from the trachea and lung was determined using a pour plate technique on samples collected at intervals after infection. Samples from turkeys which had been infected with AIV were found to yield more P multocida than those from turkeys which had not been infected with AIV. The numbers of P multocida increased in infected birds to a greater extent than in birds which had not been infected with the virus. The present study suggests that AIV infection may contribute to the increased numbers and a decreased clearance of P multocida in turkeys.