Genomic signatures of human versus avian influenza A viruses

Position-specific entropy profiles created from scanning 306 human and 95 avian influenza A viral genomes showed that 228 of 4591 amino acid residues yielded significant differences between these 2 viruses. We subsequently used 15,785 protein sequences from the National Center for Biotechnology Information (NCBI) to assess the robustness of these signatures and obtained 52 "species-associated" positions. Specific mutations on those points may enable an avian influenza virus to become a human virus. Many of these signatures are found in NP, PA, and PB2 genes (viral ribonucleoproteins [RNPs]) and are mostly located in the functional domains related to RNP-RNP interactions that are important for viral replication. Upon inspecting 21 human-isolated avian influenza viral genomes from NCBI, we found 19 that exhibited > or =1 species-associated residue changes; 7 of them contained > or =2 substitutions. Histograms based on pairwise sequence comparison showed that NP disjointed most between human and avian influenza viruses, followed by PA and PB2.     

Control of avian influenza in poultry

Avian influenza, listed by the World Organization for Animal Health (OIE), has become a disease of great importance for animal and human health. Several aspects of the disease lack scientific information, which has hampered the management of some recent crises. Millions of animals have died, and concern is growing over the loss of human lives and management of the pandemic potential. On the basis of data generated in recent outbreaks and in light of new OIE regulations and maintenance of animal welfare, we review the available control methods for avian influenza infections in poultry, from stamping out to prevention through emergency and prophylactic vaccination.     

Prior infection of chickens with H1N1 avian influenza virus elicits heterologous protection against highly pathogenic H5N2

Current vaccines for influenza are primarily killed whole virus vaccines that elicit antibody responses to the homologous virus but lack protection against heterologous viruses. Using chickens as a model we have explored the possibility of using a live low pathogenic avian influenza (LPAI) A/goose/AB/223/2005 H1N1 virus as a vaccine to generate protective immunity against heterologous highly pathogenic avian influenza (HPAI) A/chicken/Pensylvania/1370/1983 H5N2 virus challenge. Virus replicated in chickens infected with LPAI H1N1 but did not cause clinical disease. In addition, these chickens developed neutralizing antibodies to LPAI H1N1 virus, but not HPAI H5N2, 21 days post infection (DPI). Furthermore, peripheral blood mononuclear cells from H1N1-infected chickens at 20 DPI had antigen specific proliferation and IFN-γ secretion following antigen stimulation to H5N2 indicating a heterologous HPAI H5N2 specific cell mediated immunity (CMI) following LPAI H1N1 infection. Following challenge with HPAI H5N2 virus, all control chickens developed clinical disease, while chickens previously infected with H1N1 did not develop clinical disease and shed significantly less virus by oral and cloacal routes. These results indicated that previous infection with LPAI virus can generate heterologous CMI capable of protecting against HPAI H5N2.     

Suboptimal protection against H5N1 highly pathogenic avian influenza viruses from Vietnam in ducks vaccinated with commercial poultry vaccines

Domestic ducks are the second most abundant poultry species in many Asian countries including Vietnam, and play a critical role in the epizootiology of H5N1 highly pathogenic avian influenza (HPAI) [FAO]. In this study, we examined the protective efficacy in ducks of two commercial H5N1 vaccines widely used in Vietnam; Re-1 containing A/goose/Guangdong/1/1996 hemagglutinin (HA) clade 0 antigens, and Re-5 containing A/duck/Anhui/1/2006 HA clade 2.3.4 antigens. Ducks received two doses of either vaccine at 7 and at 14 or 21 days of age followed by challenge at 30 days of age with viruses belonging to the HA clades 1.1, 2.3.4.3, 2.3.2.1.A and 2.3.2.1.B isolated between 2008 and 2011 in Vietnam. Ducks vaccinated with the Re-1 vaccine were protected after infection with the two H5N1 HPAI viruses isolated in 2008 (HA clades 1.1 and 2.3.4.3) showing no mortality and limited virus shedding. The Re-1 and Re-5 vaccines conferred 90–100% protection against mortality after challenge with the 2010 H5N1 HPAI viruses (HA clade 2.3.2.1.A); but vaccinated ducks shed virus for more than 7 days after challenge. Similarly, the Re-1 and Re-5 vaccines only showed partial protection against the 2011 H5N1 HPAI viruses (HA clade 2.3.2.1.A and 2.3.2.1.B), with a high proportion of vaccinated ducks shedding virus for more than 10 days. Furthermore, 50% mortality was observed in ducks vaccinated with Re-1 and challenged with the 2.3.2.1.B virus. The HA proteins of the 2011 challenge viruses had the greatest number of amino acid differences from the two vaccines as compared to the viruses from 2008 and 2009, which correlates with the lesser protection observed with these viruses. These studies demonstrate the suboptimal protection conferred by the Re-1 and Re-5 commercial vaccines in ducks against H5N1 HPAI clade 2.3.2.1 viruses, and underscore the importance of monitoring vaccine efficacy in the control of H5N1 HPAI in ducks.     

Vaccine protection of chickens against antigenically diverse H5 highly pathogenic avian influenza isolates with a live HVT vector vaccine expressing the influenza hemagglutinin gene derived from a clade 2.2 avian influenza virus

Vaccination is an important tool in the protection of poultry against avian influenza (AI). For field use, the overwhelming majority of AI vaccines produced are inactivated whole virus formulated into an oil emulsion. However, recombinant vectored vaccines are gaining use for their ability to induce protection against heterologous isolates and ability to overcome maternal antibody interference. In these studies, we compared protection of chickens provided by a turkey herpesvirus (HVT) vector vaccine expressing the hemagglutinin (HA) gene from a clade 2.2 H5N1 strain (A/swan/Hungary/4999/2006) against homologous H5N1 as well as heterologous H5N1 and H5N2 highly pathogenic (HP) AI challenge. The results demonstrated all vaccinated birds were protected from clinical signs of disease and mortality following homologous challenge. In addition, oral and cloacal swabs taken from challenged birds demonstrated that vaccinated birds had lower incidence and titers of viral shedding compared to sham-vaccinated birds. Following heterologous H5N1 or H5N2 HPAI challenge, 80–95% of birds receiving the HVT vector AI vaccine at day of age survived challenge with fewer birds shedding virus after challenge than sham vaccinated birds. In vitro cytotoxicity analysis demonstrated that splenic T lymphocytes from HVT-vector-AI vaccinated chickens recognized MHC-matched target cells infected with H5, as well as H6, H7, or H9 AI virus. Taken together, these studies provide support for the use of HVT vector vaccines expressing HA to protect poultry against multiple lineages of HPAI, and that both humoral and cellular immunity induced by live vaccines likely contributes to protection.     

安徽省人感染高致病性禽流感健康传播项目效果评价

目的:评价在家禽养殖和加工/销售人员开展"预防人感染高致病性禽流感健康传播项目"的效果。方法:抽取安徽省两个项目县部分家禽养殖和加工/销售人员,采取小组访谈和问卷调查的方法评价项目干预前后知信行变化。结果:干预前后家禽养殖和加工/销售人员在禽流感预防的核心信息的知晓率由干预前的30.0%~57.5%提高到55.9%~88.2%,对国家预防和控制禽流感相关政策持赞同态度的由干预前的67.5%~82.5%上升到85.3~97.1%,认为自己作用非常重要,由干预前的67.5%上升为94.1%,与干预前日常接触禽类后很少防护相比,干预后被调查人员均注意手和衣物的清洗消毒。结论:人感染高致病性禽流感健康传播项目对提高禽类养殖和加工/销售者相关知识、信念和行为效果明显,传播干预策略有效,应建立一种持续、长效的健康传播机制。     

Protection and virus shedding of falcons vaccinated against highly pathogenic avian influenza A virus (H5N1)

Because fatal infections with highly pathogenic avian influenza A (HPAI) virus subtype H5N1 have been reported in birds of prey, we sought to determine detailed information about the birds' susceptibility and protection after vaccination. Ten falcons vaccinated with an inactivated influenza virus (H5N2) vaccine seroconverted. We then challenged 5 vaccinated and 5 nonvaccinated falcons with HPAI (H5N1). All vaccinated birds survived; all unvaccinated birds died within 5 days. For the nonvaccinated birds, histopathologic examination showed tissue degeneration and necrosis, immunohistochemical techniques showed influenza virus antigen in affected tissues, and these birds shed high levels of infectious virus from the oropharynx and cloaca. Vaccinated birds showed no influenza virus antigen in tissues and shed virus at lower titers from the oropharynx only. Vaccination could protect these valuable birds and, through reduced virus shedding, reduce risk for transmission to other avian species and humans.     

人禽流感疫区居民对防控措施效果满意度调查

目的了解江西省遂川县人禽流感发生1年后疫区居民对防控措施的评价。方法采用以户为单位的系统抽样方法,在疫区抽取396名14岁~居民进行问卷调查。结果89.2%的疫区居民对政府在人禽流感发生后所采取的防控措施感到满意;56.3%的居民认为将来不会再发生人禽流感疫情,且非疫点居民信心度低于疫点居民(P<0.001);77.2%的居民认为当前防控措施有效。结论对政府在1年前的疫情处理,疫区居民基本上满意;对当前政府防控同类事件的措施和能力也有较好的评价,但对将来不会再发生人禽流感事件的信心显得不足,尤其是非疫点居民。     

Immunologic evaluation of 10 different adjuvants for use in vaccines for chickens against highly pathogenic avian influenza virus

Avian influenza viruses (AIV) are a threat to poultry production worldwide. Vaccination is utilized as a component of control programs for both high pathogenicity (HP) and low pathogenicity (LP) AIV. Over 95% of all AIV vaccine used in poultry are inactivated, adjuvanted products. To identify the best formulations for chickens, vaccines were prepared with beta-propiolactone (BPL) inactivated A/British Columbia/314514-1/2004 H7N3 LP AIV using ten commercially available or experimental adjuvants. Each vaccine formulation was evaluated for immunogenicity in chickens. Challenge studies with an antigenically homologous strain of HPAIV were conducted to compare protection against mortality and measure reductions in virus levels in oral swabs. The four best adjuvants from the studies with BPL inactivated antigen were selected and tested identically, but with vaccines prepared from formalin inactivated virus. Mineral and vegetable oil based adjuvants generally induced the highest antibody titers with 100% seroconversion by 3 weeks post vaccination. Chitosan induced positive antibody titers in 100% of the chickens, but the titers were significantly lower than those of most of the oil based adjuvants. Antibody levels from calcium phosphate and alginate adjuvanted groups were similar to those of non-adjuvanted virus. All groups that received adjuvanted vaccines induced similar levels of protection against mortality (0–20%) except the groups vaccinated with calcium phosphate adjuvanted vaccines, where mortality was similar (70%) to groups that received non-adjuvanted inactivated virus or no vaccine (60–100% mortality). Virus shedding in oral swabs was variable among the treatment groups. Formalin inactivated vaccine induced similar antibody titers and protection against challenge compared to BPL inactivated vaccine groups. These studies support the use of oil adjuvanted vaccines for use in the poultry industry for control for AIV.     

Movements of birds and avian influenza from Asia into Alaska

Asian-origin avian influenza (AI) viruses are spread in part by migratory birds. In Alaska, diverse avian hosts from Asia and the Americas overlap in a region of intercontinental avifaunal mixing. This region is hypothesized to be a zone of Asia-to-America virus transfer because birds there can mingle in waters contaminated by wild-bird-origin AI viruses. Our 7 years of AI virus surveillance among waterfowl and shorebirds in this region (1998-2004; 8,254 samples) showed remarkably low infection rates (0.06%). Our findings suggest an Arctic effect on viral ecology, caused perhaps by low ecosystem productivity and low host densities relative to available water. Combined with a synthesis of avian diversity and abundance, intercontinental host movements, and genetic analyses, our results suggest that the risk and probably the frequency of intercontinental virus transfer in this region are relatively low.     

Protective immunity against avian influenza induced by a fowlpox virus recombinant

Fowlpox virus, the prototypic virus of the genus Avipoxvirus has a natural host range limited to avian species. As such, fowlpox virus provides a suitable candidate for the development of a species-specific recombinant viral vector. This paper reports the development of a fowlpox virus recombinant expressing the haemagglutinin molecule from a highly virulent avian influenza virus. On immunization of chickens and turkeys with the recombinant, protection is afforded against a lethal challenge with either the homologous or a heterologous influenza virus strain.     

Mallards and highly pathogenic avian influenza ancestral viruses, northern Europe

Outbreaks of highly pathogenic avian influenza (HPAI), which originate in poultry upon transmission of low pathogenic viruses from wild birds, have occurred relatively frequently in the last decade. During our ongoing surveillance studies in wild birds, we isolated several influenza A viruses of hemagglutinin subtype H5 and H7 that contain various neuraminidase subtypes. For each of the recorded H5 and H7 HPAI outbreaks in Europe since 1997, our collection contained closely related virus isolates recovered from wild birds, as determined by sequencing and phylogenetic analyses of the hemagglutinin gene and antigenic characterization of the hemagglutinin glycoprotein. The minor genetic and antigenic diversity between the viruses recovered from wild birds and those causing HPAI outbreaks indicates that influenza A virus surveillance studies in wild birds can help generate prototypic vaccine candidates and design and evaluate diagnostic tests, before outbreaks occur in animals and humans.     

甘肃省预防人感染高致病性禽流感健康教育效果评价

目的评价“预防人感染高致病性禽流感健康传播项目”的实施效果,对在农村地区开展预防人感染高致病性禽流感的健康传播措施进行探讨。方法设计人禽流感知信行调查问卷,采用两次重复横断面调查方法进行。分别于项目实施前、后对目标人群进行两次调查,比较项目实施前后目标人群对预防人感染高致病性禽流感核心知识的知晓、态度及高危行为的改变情况。结果学生禽流感知识正确回答率干预前与干预后明显提高。“不接触禽类”干预前为43．6％,干预后为88．3％。“远离禽类粪便”干预前为54．2％,干预后为97．7％。社区高危人群禽流感知识干预后知识来源途径广泛,各途径获得知识的人数均较干预前显著提高,尤其是来源于小册子,妇女主任及其他村干部、小学生者达100％。结论知识正确掌握率,不论学生、社区高危人群,干预后均较干预前有大幅度的提高,说明传播策略非常有效。     

Reduction of high pathogenicity avian influenza virus in eggs from chickens once or twice vaccinated with an oil-emulsified inactivated H5 avian influenza vaccine

The negative impact of high pathogenicity avian influenza virus (HPAIV) infection on egg production and deposition of virus in eggs, as well as any protective effect of vaccination, is unknown. Individually housed non-vaccinated, sham-vaccinated and inactivated H5N9 vaccinated Once or Twice adult White leghorn hens were challenged intranasally/intratracheally 3-weeks post-vaccination with H5N2 HPAIV. The non-/sham-vaccinated layers experienced 100% mortality (0% survivability) within 3-4 days post-challenge (DPC), and major changes to reproductive parameters including precipitous drops in egg production (79-0% in <5 days), production of soft and thin-shelled eggs, and deposition of virus in albumin and yolk, and on the egg shell surface of 53% of eggs. By comparison, the three H5-vaccinated groups had 83%, 100% and 100% survivability after challenge; the two H5-vaccinated Once hens that died had low pre-challenge HI titers (GMT=16). H5-vaccinated Once or Twice groups maintained egg production after challenge (63%), but there was a mild and significant reduction in egg production as compared to pre-challenge egg production (79%). H5-vaccinated groups had reduced number of virus contaminated eggs (28%), and in most groups, reduced quantity of virus in contaminated eggs compared to non-/sham-vaccinated groups. No HPAIV-positive eggs were laid on or after 5 DPC. In conclusion, HPAIV infection had major negative impact on egg production and other reproductive parameters. H5-vaccination Once or Twice prevented declines in egg production after HPAIV challenge, reduced number of virus-infected eggs, and typically reduced the titer of virus in internal contents and on eggshell surface.     

2013-2017年惠州市重症社区获得性肺炎病例甲型流感/禽流感监测结果分析

目的 通过对重症社区获得性肺炎(severe community-acquired pneumonia, SCAP)病例进行甲型流感/禽流感病原学检测,及时发现流感和人间禽流感疫情,为流感和禽流感疫情预测预警提供科学依据。方法 以惠州市最大三甲综合医院为哨点医院采集病例标本,采用实时荧光定量PCR方法,开展SCAP病例的甲型流感和禽流感病原体监测。结果 2013年1月-2017年12月,共完成652例SCAP病例样品的采集和检测,SCAP病例主要为5岁以下和60岁以上人群,病例时间分布高峰期为1-3和12月份,与甲流阳性率一致;652例SCAP病例中,有123份甲型流感病例,主要亚型为甲型H1N1,共85份(69.11%);5岁以下和60岁以上年龄组甲流阳性率最高,各年龄组阳性率差异有统计学意义(χ²=24.379,P=0.002);共检出9例禽流感病例,年龄主要分布在50～60岁,女性人数多于男性,发病时间大部分集中在2月份;首例H7N9病例病毒序列与国内同期病毒有高度同源。结论 2013-2017年惠州市SCAP流行有明显的季节性,5岁以下儿童和60岁以上的老年人是SCAP病例的主要人群,甲型流感阳性率也最高,在流感流行季节对以上人群进行流感疫苗接种,可有效预防由于流感导致的SCAP;开展SCAP病例的甲型流感和禽流感病原体监测项目,可以及时发现高致病性人禽流感病例,对禽流感的早期预警和疫情管理有很好的指导意义。     

吉林省活禽市场外环境禽流感污染情况调查

目的了解吉林省活禽市场外环境禽流感病毒分布状况。方法于2014年3月1日-10日采集吉林省活禽市场外环境,共抽取370个采样点,每个点抽取50家活禽摊位采集外环境鸡笼涂抹、鸡粪和污水标本,采用实时荧光定量 PCR 法检测禽流感病毒FluA H5、H9和H7核酸。结果370个采样点中58个（15.68%）检出阳性标本,各地区标本核酸阳性率有明显差异（P<0.05）;共采集活禽市场外环境标本1 110份,分别为污水359份,粪便381份,笼具擦拭物370份,其中阳性94份,H9阳性60份,H5阳性30份,H5/H9混合阳性4份,未检测出H7阳性,不同类型标本的阳性检出率无统计学差异。结论吉林省活禽市场环境存在禽流感病毒的污染,主要型别为H9和H5亚型,未发现H7亚型。     

家禽零售及饲养人群禽流感病毒抗体检测分析

目的 了解广东省广州市不同类型禽类从业人群禽流感病毒H5、H9的感染状况。方法 采集肉菜市场家禽零售人员、大型家禽饲养企业工人、农村个体家禽散养人员的全血标本,用微量血凝抑制试验检测H5、H9抗体。结果 共调查369名禽类从业人员,其中家禽零售人员H9抗体阳性率(16.46%,13/79)高于家禽散养人员(3.40%,5/147)和企业饲养工人(4.90%,7/143),差异均有统计学意义(P<0.02);家禽散养人员与企业饲养工人H9抗体阳性率差异无统计学意义。所有禽类从业人员H5抗体均为阴性。结论 肉菜市场家禽零售人员感染禽流感病毒的风险高于大型家禽饲养企业工人和农村个体家禽散养人员。     

Transmission of avian influenza virus (H3N2) to dogs

In South Korea, where avian influenza virus subtypes H3N2, H5N1, H6N1, and H9N2 circulate or have been detected, 3 genetically similar canine influenza virus (H3N2) strains of avian origin (A/canine/Korea/01/2007, A/canine/Korea/02/2007, and A/canine/Korea/03/2007) were isolated from dogs exhibiting severe respiratory disease. To determine whether the novel canine influenza virus of avian origin was transmitted among dogs, we experimentally infected beagles with this influenza virus (H3N2) isolate. The beagles shed virus through nasal excretion, seroconverted, and became ill with severe necrotizing tracheobronchitis and bronchioalveolitis with accompanying clinical signs (e.g., high fever). Consistent with histologic observation of lung lesions, large amounts of avian influenza virus binding receptor (SAalpha 2,3-gal) were identified in canine tracheal, bronchial, and bronchiolar epithelial cells, which suggests potential for direct transmission of avian influenza virus (H3N2) from poultry to dogs. Our data provide evidence that dogs may play a role in interspecies transmission and spread of influenza virus.