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1.
从天津地区不同猪场分离到6株H1N1亚型猪源流感病毒（SIV）。根据GenBank发表的H1N1亚型 SIV的核蛋白（NP）、基质蛋白（M）及非结构蛋白（NS）基因序列,分别设计3对引物,将RT-PCR产物克隆至pMD18-T载体,进行测序分析。遗传进化分析结果表明：A/swine/Tianjin/TJ2/2005（H1N1）与A/swine/Tianjin/TJ4/2006（H1N1）的NP、M及NS基因核苷酸序列在遗传进化树中均与A/swine/Guangdong/33/2006（H1N1）位于同一分支上,属于古典型H1N1猪谱系;A/swine/Tianjin/TJ3/2006（H1N1）与A/swine/Tianjin/TJ8/2006（H1N1)的NP、M及NS基因核苷酸在遗传进化树中均与A/Dunedin/2/2000（H1N1）组成一个大分支,可能起源于人谱系;A/swine/Tianjin/TJ6/2009（H1N1）与A/swine/Tianjin/TJ7/2009（H1N1）NP、M及NS基因核苷酸序列在遗传进化树中均与A/swine/Jiangsu/s15/2011（H1N1）位于同一分支上,属于类禽H1N1猪谱系。本试验对6株H1N1亚型SIV的NP、M及NS全基因序列进行分析,在一定程度上揭示了天津地区H1N1亚型SIV的基因进化与流行情况。  相似文献   

2.
Genetic reassortment between human and avian influenza viruses can create pandemic viruses. Influenza surveillance of pigs in Jilin Province, in China during 2007–2008 revealed that there were two distinguishable genotypes: a human-like H3N2 genotype and a double-reassortant genotype derived from the human H3N2 and avian H5 viruses. In this study, viral infection potential, replication kinetics, and pathogenicity were compared. The solid-phase binding assay demonstrated that both viruses prominently maintained a preference for the human-type receptor and the reassortant A/swine/Jilin/37/2008 (Sw/JL/37/08) showed relatively higher binding affinities than the non-reassortant A/swine/Jilin/19/2007 (Sw/JL/19/07). Replication kinetics showed that Sw/JL/37/08 had higher replicability in MDCK cells than Sw/JL/19/07. The mouse experiments clearly revealed that Sw/JL/37/08 had higher virulence than Sw/JL/19/07 as measured by more significant body weight loss, higher viral lung load, delayed viral clearance from lungs, and more severe pulmonary lesions. Sequence analysis indicated that the absence of glycosylation sites at residue 126 of HA and 93 of NA, as well as the characteristic NS1 C-terminal PL residues of ESEV may account for the increased replication and pathogenicity of Sw/JL/37/08. These results may imply that human may have infection risk by the reassortant swine influenza virus and emphasize the necessity for enhanced viral surveillance strategies, which monitor reassortment events in nature to reduce the public health threat posed by influenza viruses with the potential for human-to-human transmission currently circulating in pig populations.  相似文献   

3.
Swine influenza viruses H1N1 and H3N2 have been reported in the swine population worldwide. From June 2008 to June 2009, we carried out serological and virological surveillance of swine influenza in the Hubei province in central China. The serological results indicated that antibodies to H1N1 swine influenza virus in the swine population were high with a 42.5% (204/480) positive rate, whereas antibodies to H3N2 swine influenza virus were low with a 7.9% (38/480) positive rate. Virological surveillance showed that only one sample from weanling pigs was positive by RT-PCR. Phylogenetic analysis of the hemagglutinin and neuraminidase genes revealed that the A/Sw/HB/S1/2009 isolate was closely related to avian-like H1N1 viruses and seemed to be derived from the European swine H1N1 viruses. In conclusion, H1N1 influenza viruses were more dominant in the pig population than H3N2 influenza viruses in central China, and infection with avian-like H1N1 viruses persistently emerged in the swine population in the area.  相似文献   

4.
Swine influenza monitoring programs have been in place in Italy since the 1990 s and from 2009 testing for the pandemic H1N1/2009 virus (H1N1pdm) was also performed on all the swine samples positive for type A influenza. This paper reports the isolation and genomic characterization of a novel H1N2 swine influenza reassortant strain from pigs in Italy that was derived from the H1N1pdm virus. In May 2010, mild respiratory symptoms were observed in around 10% of the pigs raised on a fattening farm in Italy. Lung homogenate taken from one pig showing respiratory distress was tested for influenza type A and H1N1pdm by two real time RT-PCR assays. Virus isolation was achieved by inoculation of lung homogenate into specific pathogen free chicken embryonated eggs (SPF CEE) and applied onto Caco-2 cells and then the complete genome sequencing and phylogenetic analysis was performed from the CEE isolate. The lung homogenate proved to be positive for both influenza type A (gene M) and H1N1pdm real time RT-PCRs. Virus isolation (A/Sw/It/116114/2010) was obtained from both SPF CEE and Caco-2 cells. Phylogenetic analysis showed that all of the genes of A/Sw/It/116114/2010, with the exception of neuraminidase (NA), belonged to the H1N1pdm cluster. The NA was closely related to two H1N2 double reassortant swine influenza viruses (SIVs), previously isolated in Sweden and Italy. NA sequences for these three strains were clustering with H3N2 SIVs. The emergence of a novel reassortant H1N2 strain derived from H1N1pdm in swine in Italy raises further concerns about whether these viruses will become established in pigs. The new reassortant not only represents a pandemic (zoonotic) threat but also has unknown livestock implications for the European swine industry.  相似文献   

5.
Yu H  Zhou YJ  Li GX  Ma JH  Yan LP  Wang B  Yang FR  Huang M  Tong GZ 《Veterinary microbiology》2011,149(1-2):254-261
Pandemic strains of influenza A virus might arise by genetic reassortment between viruses from different hosts. Pigs are susceptible to both human and avian influenza viruses and have been proposed to be intermediate hosts or mixing vessels, for the generation of pandemic influenza viruses through reassortment or adaptation to the mammalian host. In this study, we summarize and report for the first time the coexistence of 10 (A-J) genotypes in pigs in China by analyzing the eight genes of 28 swine H9N2 viruses isolated in China from 1998 to 2007. Swine H9N2 viruses in genotype A and B were completely derived from Y280-like and Shanghai/F/98-like viruses, respectively, which indicated avian-to-pig interspecies transmission of H9N2 viruses did exist in China. The other eight genotype (C-J) viruses might be double-reassortant viruses, in which six genotype (E-J) viruses possessed 1-4 H5-like gene segments indicating they were reassortants of H9 and H5 viruses. In conclusion, genetic diversity of H9N2 influenza viruses from pigs in China provides further evidence that avian to pig interspecies transmission of H9N2 viruses did occur and might result in the generation of new reassortant viruses by genetic reassortment with swine H1N1, H1N2 and H3N2 influenza viruses, therefore, these swine H9N2 influenza viruses might be a potential threat to human health and continuing to carry out swine influenza virus surveillance in China is of great significance.  相似文献   

6.
Since the first detection of human H3N2 influenza virus in Taiwanese pigs in 1970, infection of pigs with wholly human viruses has been known to occur in other parts of the world. These viruses, referred to as human‐like H3N2 viruses, have been known to cause clinical and subclinical infections of swine populations. Due to the paucity and complete unavailability of information on transmission of influenza viruses from other species, especially humans, to swine in Nigeria and Ghana, respectively, this study was designed to investigate the presence and prevalence of a human strain of influenza A (H3N2) in swine populations at three locations in two cities within these two West African countries in January and February, 2014. Using stratified random technique, nasal swab specimens were collected from seventy‐five (75) pigs at two locations in Ibadan, Nigeria and from fifty (50) pigs in Kumasi, Ghana. These specimens were tested directly by a sensitive Quantitative Solid Phase Antigen‐detection Sandwich ELISA using anti‐A/Brisbane/10/2007 haemagglutinin monoclonal antibody. Influenza virus A/Brisbane/10/2007 (H3N2) was detected among pigs at the three study locations, with an aggregate prevalence of 4.0% for the two locations in Ibadan, Nigeria and also 4.0% for Kumasi, Ghana. Transmission of influenza viruses from other species to swine portends serious sinister prospects for genetic reassortment and evolvement of novel viruses. We therefore recommend that further studies should be carried out to investigate the presence of other circulating human and avian influenza viruses in swine populations in West Africa and also determine the extent of genetic reassortment of strains circulating among these pigs. This would provide an early warning system for detection of novel influenza viruses, which could have pandemic potentials.  相似文献   

7.
The efficacy of a commercial swine influenza vaccine based on A/New Jersey/8/76 (H1N1) and A/Port Chalmers/1/73 (H3N2) strains was tested against challenge with an H1N2 swine influenza virus. Influenza virus-seronegative pigs were vaccinated twice with the vaccine when they were four and eight weeks old, or with the same vaccine supplemented with an H1N2 component. Control pigs were left unvaccinated. Three weeks after the second vaccination, all the pigs were challenged intratracheally with the swine influenza strain Sw/Gent/7625/99 (H1N2). The commercial vaccine induced cross-reactive antibodies to H1N2, as detected by the virus neutralisation (VN) assay, but VN antibody titres were 18 times lower than in the pigs vaccinated with the H1N2-supplemented vaccine. The challenge produced severe respiratory signs in nine of 10 unvaccinated control pigs, which developed high H1N2 virus titres in the lungs 24 and 72 hours after the challenge. Vaccination with the commercial vaccine resulted in milder respiratory signs, but H1N2 virus replication was not prevented. Mean virus titres in the pigs vaccinated with the commercial vaccine were 1-5 log10 lower than in the controls at 24 hours but no different at 72 hours. In contrast, the H1N2-supplemented vaccine prevented respiratory disease in most pigs. There was a 4-5 log10 reduction in the mean virus titre at 24 hours in the pigs vaccinated with this vaccine, and no detectable virus replication at 72 hours. These data indicate that the commercial swine influenza vaccine did not confer adequate protection against the H1N2 subtype.  相似文献   

8.
Influenza‐like illness was noted in people and pigs in attendance at an Ohio county fair in August 2007. The morbidity rate in swine approached 100% within 1–2 days of initial clinical signs being recognized, and approximately two dozen people developed influenza‐like illness. Triple‐reassortant swine H1N1 influenza viruses were identified in both pigs and people at the fair. The identified viruses (A/Sw/OH/511445/2007, A/Ohio/01/2007, and A/Ohio/02/2007) were similar to H1N1 swine influenza viruses currently found in the U.S. swine population. This case illustrates the possibility of transmission of swine influenza in settings where there is close human/swine interaction.  相似文献   

9.
为了解猪流感病毒(SIV)的变异情况,我们2009年11月从河北某养殖场采集呈流感症状的猪鼻拭子40份,接种10日龄SPF鸡胚,分离到一株猪流感病毒,通过RT-PCR和血凝抑制试验鉴定为H1N1亚型,命名为A/swine/Hebei/15/2009(H1N1),其全基因序列测定及同源性分析发现,8个基因片段均与2000年左右H1N1人流感病毒有较高的同源性。系统遗传演化显示,该病毒分离株是由2000年人源H1N1流感病毒A/Dunedin/2/2000(H1N1)进化而来。抗原性分析显示该株与甲型H1N1流感病毒和经典H1N1病毒株抗原性差异较大。对小鼠致病性试验表明该病毒株可以直接感染小鼠并导致小鼠轻微临床症状和组织病理学变化,但不致死小鼠,表现为低致病性。  相似文献   

10.
Because pigs have respiratory epitheliums which express both α2-3 and α2-6 linked sialic acid as receptors to influenza A viruses, they are regarded as mixing vessel for the generation of pandemic influenza viruses through genetic reassortment. A H7N2 influenza virus (A/swine/KU/16/2001) was isolated from pig lungs collected from the slaughterhouse. All eight genes of the influenza virus were sequenced and phylogenetic analysis indicated that A/swine/KU/16/2001 originated in Hong Kong and genetic reassortment had occurred between the avian H7N2 and H5N3 influenza viruses. The first isolation of H7 influenza virus in pigs provides the opportunity for genetic reassortment of influenza viruses with pandemic potential and emphasizes the importance of surveillance for atypical swine influenza viruses.  相似文献   

11.
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12.
This approach maximizes sensitivity of serology-based monitoring systems by considering spatial clustering of herds classified as false positive by herd testing, allowing outbreaks to be detected in an early phase. The primary objective of this study was to determine whether swine herds infected with influenza viruses cluster in space, and if so, where they cluster. The secondary objective was to investigate the combining of a multivariate spatial scan statistic with herd test results to maximize the sensitivity of the surveillance system for swine influenza. We tested for spatial clustering of swine influenza using the Cuzick–Edwards test as a global test. The location of the most likely spatial clusters of cases for each subtype and strain in a sample of 65 sow and 72 finisher herds in 2001 (Ontario, Canada), and 76 sow herds in 2003 (Ontario, Canada) was determined by a spatial scan statistic in a purely spatial Bernoulli model based on single and multiple datasets.

A case herd was defined by true herd-disease status for sow or finisher herds tested for H1N1, and by apparent herd-disease status for sow herds tested for two H3N2 strains (A/Swine/Colorado/1/77 (Sw/Col/77) and A/Swine/Texas/4199-2/98 (Sw/Tex/98)). In sow herds, there was no statistically significant clustering of H1N1 influenza after adjustment for pig-farm density. Similarly, spatial clustering was not found in finisher herds. In contrast, clustering of H3N2 Sw/Col/77 (prevalence ratio = 12.5) and H3N2 Sw/Tex/98 (prevalence ratio = 15) was identified in an area close to a region with documented isolation of avian influenza isolates from pigs.

For the H1N1 subtype tested by ELISA, we used an approach that minimized overall misclassification at the herd level. This could be more applicable for detecting clusters of positive farms when herd prevalence is moderate to high than when herd prevalence is low. For the H3N2 strains we used an approach that maximized herd-level sensitivity by minimizing the herd cut-off. This is useful in situations where prevalence of the pathogen is low. The results of applying a multivariate spatial scan statistic approach, led us to generate the hypothesis that an unknown variant of influenza of avian origin was circulating in swine herds close to an area where avian strains had previously been isolated from swine. Maximizing herd sensitivity and linking it with the spatial information can be of use for monitoring of pathogens that exhibit the potential for rapid antigenic change, which, consequently, might then lead to diminished cross-reactivity of routinely used assays and lower test sensitivity for the newly emerged variants. Veterinary authorities might incorporate this approach into animal disease surveillance programs that either substantiate freedom from disease, or are aimed at detecting early incursion of a pathogen, such as influenza virus, or both.  相似文献   


13.
As pigs are susceptible to infection with both avian and human influenza A viruses, they have been proposed to be an intermediate host for the adaptation of avian influenza viruses to humans. In April 2006, a disease caused by highly pathogenic porcine reproductive and respiratory syndrome virus (PRRSV) occurred in several pig farms and subsequently overwhelmed almost half of China with more than 2,000,000 cases of pig infection. Here we report a case in which four swine H9N2 influenza viruses were isolated from pigs infected by highly pathogenic PRRSVs in Guangxi province in China. All the eight gene segments of the four swine H9N2 viruses are highly homologous to A/Pigeon/Nanchang/2-0461/00 (H9N2) or A/Wild Duck/Nanchang/2-0480/00 (H9N2). Phylogenetic analyses of eight genes show that the swine H9N2 influenza viruses are of avian origin and may be the descendants of A/Duck/Hong Kong/Y280/97-like viruses. Molecular analysis of the HA gene indicates that our H9N2 isolates might have high-affinity binding to the alpha2,6-NeuAcGal receptor found in human cells. In conclusion, our finding provides further evidence about the interspecies transmission of avian influenza viruses to pigs and emphasizes the importance of reinforcing swine influenza virus (SIV) surveillance, especially after the emergence of highly pathogenic PRRSVs in pigs in China.  相似文献   

14.
2007-2008年从吉林省某猪场采集疑似流感发病猪的鼻咽拭子,经病毒分离鉴定获得3株H3N2亚型流感病毒,分别命名为A/swine/Jilin/5/2007（Sw/Jilin/5/07）、A/swine/Jilin/19/2007（Sw/Jilin/19/07）、A/swine/Jilin/37/2008（Sw/Jilin/37/08）。HA进化树分析结果表明：3株H3N2亚型流感病毒属于近代人源病毒谱系;但是在NA进化树中,Sw/Jilin/37/08株与早期人源和近代人源关系密切,暗示它可能是早期人源和近代人源H3N2亚型猪流感病毒之间的过渡毒株,进一步证实猪在流感病毒种间传播过程中充当＂中间宿主＂作用。  相似文献   

15.
Influenza A is a respiratory disease common in the swine industry. Three subtypes, H1N1, H1N2 and H3N2 influenza A viruses, are currently co-circulating in swine populations in Korea. An outbreak of the highly pathogenic avian influenza H5N1 virus occurred in domestic bird farms in Korea during the winter season of 2003. Pigs can serve as hosts for avian influenza viruses, enabling passage of the virus to other mammals and recombination of mammalian and avian influenza viruses, which are more readily transmissible to humans. This study reports the current seroprevalence of swine H1 and H3 influenza in swine populations in Korea by hemagglutination inhibition (HI) assay. We also investigated whether avian H5 and H9 influenza transmission occurred in pigs from Korea using both the HI and neutralization (NT) tests. 51.2% (380/742) of serum samples tested were positive against the swine H1 virus and 43.7% (324/742) were positive against the swine H3 virus by HI assay. The incidence of seropositivity against both the swine H1 virus and the swine H3 virus was 25.3% (188/742). On the other hand, none of the samples tested showed seropositivity against either the avian H5 virus or the avian H9 virus by the HI and NT tests. Therefore, we report the high current seroprevalence and co-infectivity of swine H1 and H3 influenza viruses in swine populations and the lack of seroepidemiological evidence of avian H5 and H9 influenza transmission to Korean pigs.  相似文献   

16.
Antigenic drift of swine influenza A (H3N2) viruses away from the human A/Port Chalmers/1/73 (H3N2) strain, used in current commercial swine influenza vaccines, has been demonstrated in The Netherlands and Belgium. Therefore, replacement of this human strain by a more recent swine H3N2 isolate has to be considered. In this study, the efficacy of a current commercial swine influenza vaccine to protect pigs against a recent Dutch field strain (A/Sw/Oedenrode/96) was assessed. To evaluate the level of protection induced by the vaccine it was compared with the optimal protection induced by a previous homologous infection. Development of fever, virus excretion, and viral transmission to unchallenged group mates were determined to evaluate protection. The vaccine appeared efficacious in the experiment because it was able to prevent fever and virus transmission to the unchallenged group mates. Nevertheless, the protection conferred by the vaccine was sub-optimal because vaccinated pigs excreted influenza virus for a short period of time after challenge, whereas naturally immune pigs appeared completely protected. The immune response was monitored, to investigate why the vaccine conferred a sub-optimal protection. The haemagglutination inhibiting and virus neutralising antibody responses in sera, the nucleoprotein-specific IgM, IgG, and IgA antibody responses in sera and nasal secretions and the influenza-specific lymphoproliferation responses in the blood were studied. Vaccinated pigs developed the same or higher serum haemagglutination inhibiting, virus neutralising, and nucleoprotein-specific IgG antibody titres as infected pigs but lower nasal IgA titres and lymphoproliferation responses. The lower mucosal and cell-mediated immune responses may explain why protection after vaccination was sub-optimal.  相似文献   

17.
Precision-cut lung slices of pigs were infected with five swine influenza A viruses of different subtypes (A/sw/Potsdam/15/1981 H1N1, A/sw/Bad Griesbach/IDT5604/2006 H1N1, A/sw/Bakum/1832/2000 H1N2, A/sw/Damme/IDT5673/2006 H3N2, A/sw/Herford/IDT5932/2007 H3N2). The viruses were able to infect ciliated and mucus-producing cells. The infection of well-differentiated respiratory epithelial cells by swine influenza A viruses was analyzed with respect to the kinetics of virus release into the supernatant. The highest titres were determined for H3N2/2006 and H3N2/2007 viruses. H1N1/1981 and H1N2/2000 viruses replicated somewhat slower than the H3N2 viruses whereas a H1N1 strain from 2006 multiplied at significantly lower titres than the other strains. Regarding their ability to induce a ciliostatic effect, the two H3N2 strains were found to be most virulent. H1N1/1981 and H1N2/2000 were somewhat less virulent with respect to their effect on ciliary activity. The lowest ciliostatic effect was observed with H1N1/2006. In order to investigate whether this finding is associated with a corresponding virulence in the host, pigs were infected experimentally with H3N2/2006, H1N2/2000, H1N1/1981 and H1N1/2006 viruses. The H1N1/2006 virus was significantly less virulent than the other viruses in pigs which was in agreement with the results obtained by the in vitro-studies. These findings offer the possibility to develop an ex vivo-system that is able to assess virulence of swine influenza A viruses.  相似文献   

18.
Novel swine influenza virus subtype H3N1 in Italy   总被引：2，自引：0，他引：2  
To date, three subtypes of swine influenza viruses, H1N1, H1N2, and H3N2 have been isolated in Italy. In 2006, a novel swine influenza virus subtype (H3N1) was isolated from coughing pigs. RT-PCR performed on lung tissues, experimental infection in pigs with the novel isolate, and cloning the virus by plaque assay confirmed this unique H and N combination. The novel isolate was also antigenically and genetically characterized. Genetic and phylogenetic analysis showed that the complete HA gene of the H3N1 strain has the highest nucleotide identity to three Italian H3N2 strains, one isolated in 2001 and two in 2004, whereas the full length NA sequence is closely related to three H1N1 subtype viruses isolated in Italy in 2004. The remaining genes are also closely related to respective genes found in H1N1 and H3N2 SIVs currently circulating in Italy. This suggests that the novel SIV could be a reassortant between the H3N2 and H1N1 SIVs circulating in Italy.  相似文献   

19.
Swine influenza virus (SIV) of H1N1 and H3N2 subtypes are dominated in European pigs population. "Classical swine" H1N1 subtype was replaced by "avian-like" H1N1 subtype. It co-circulates with H3N2 reassortant possessing "avian" genes. In the present study, 41 SIV strains isolated from pigs with pneumonia, raised in 20 Polish farms, were identified and characterised. Since it was evidenced that isolates from the same geographic district and the same year of isolation are in 100% similar, 15 strains representing different district and different year of isolation were chosen to construct phylogenetic trees. Two genes, conservative matrix 1 (M1) and the most variable, haemagglutynin (HA), were sequenced and subjected into phylogenetic analysis. The results of the analysis confirmed that "avian-like" swine H1N1 strains evolved faster than classical SIV strains. HA gene of these isolates have been derived from contemporary strains of "avian-like" SIV. In contrast, the M1 gene segment may have originated from avian influenza viruses. H3N2 strain is located in swine cluster, in the main prevalent European group of H3N2 isolates called A/Port Chalmers/1/73-like Eurasian swine H3N2 lineage, which has evolved separately from the human H3N2 virus lineage around 1973.  相似文献   

20.
4株不同亚型流感病毒NP基因的原核表达   总被引：1，自引：0，他引：1  
为了进一步研究A型流感病毒核蛋白功能及在诊断中的应用,采用RT-PCR技术分别扩增H1N1、H3N2、H5N1、H9N2等4株不同亚型流感病毒的NP基因,分别将其克隆到原核表达载体pET30(a)上,在大肠埃希菌中进行诱导表达.SDS-PAGE和Western blot检测结果表明,H1N1亚型流感病毒NP蛋白得到表达,并且能分别与H1N1和H5N1亚型流感病毒的鼠高免血清发生特异性反应,具有良好的反应活性;而H3N2、H5N1、H9N2亚型流感病毒的重组NP蛋白未获得表述.本研究结果表明,不同毒株的NP蛋白在大肠埃希菌中的表达具有一定差异性,为把NP蛋白作为诊断抗原的开发、ELISA诊断方法的建立以及蛋白功能的研究奠定了基础.  相似文献   

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