Ortho- and paramyxoviruses from migrating feral ducks: characterization of a new group of influenza A viruses.

Ortho- and parainfluenza viruses isolated from the cloacas of migrating feral ducks shot on the Mississippi flyway included three strains of influenza. A virus (Hav6 Nav1, Hav6 Nl, Hav7 Neq2) as well as Newcastle disease virus. One influenza virus, A/duck/Memphis/546/74, possessed Hav3 haemagglutinin, but the neuraminidase was not inhibited by any of the known influenza reference antisera. The neuraminidase on this virus was related to the neuraminidases on A/duck/GDR/72 (H2 N?), A/turkey/Ontario/7732/66 (Hav 5 N?), A/duck/Ukraine/1/60 (Hav3 N?) and A/turkey/Wisconsin/68. We therefore propose that the neuraminidase on this group of influenza viruses be designated Nav6. The A/duck/Memphis/546/74 influenza virus caused an ocular discharge in 1 of 5 ducks and was shed in faeces for 10 days; it was stable in faecal samples for up to 3 days at 20 degrees C. These results suggest that ecological studies on influenza in avian species should include attempts to isolate virus from faeces. Faecal-oral transmission is an attractive explanation for the spread of influenza virus from feral birds to other animals.     

Characterisation of influenza A viruses isolated from turkeys in England during March-May 1979

During the early spring of 1979 turkeys on at least twelve sites in England became infected with influenza A viruses. On five of these sites no virus was isolated but birds were shown to have antibodies to Havl (four sites) and Hav2 antigenic subtypes of influenza A viruses. The eight viruses isolated were typed: A/turkey/England/192-328/79 (Havl Nav2/3), A/turkey/England/192-329/79 (Hav1 N2), A/turkey/England/199/79 (Hav1 Neq1), A/turkey/ England/214/79 (Hav1 Neq1), A/turkey/England/250/79 (Hsw1 N1), A/turkey/England/262/79 (Hav1 Nav2/3), A/turkey/England/272/79 (Havl Neq1), A/turkey/England/384/79 (Hav2 Nav4). Pathogenicity index tests in 6-week-old chickens agreed with the clinical signs seen in turkeys in the field. Three of the isolates: 199, 214 and 272 were of extremely high virulence, 384 showed intermediate virulence, while the other isolates were of low virulence.     

Isolation and serological characterization of influenza A viruses from birds that were dead on arrival at Tokyo airport

Summary Twenty-two strains of influenza A virus were isolated from caged birds which had been imported into Japan from India and Thailand and had died during transportation to Tokyo.Serological tests divided these strains into two groups. Viruses in the first group contained Hav7 hemagglutinin and were related antigenically to A/duck/ Ukraine/1/63 [Hav7 Neq2]; viruses in the second group contained Hav4 hemagglutinin and were related to A/duck/Czech/56 (Hav4 Nav1]. All strains contained Neq2 neuraminidase that was closely related to that of A/equine/Miami/1/63 [Heq2 Neq2] and A/duck/Ukraine/1/63 [Hav7 Neq2]. It was concluded that the strains in the first group were Hav7 Neq2 and those in the second group were Hav4 Neq2; both groups of viruses showed antigenic drift from the prototype strains.With 2 Figures     

The "in vivo" production of "new" influenza viruses. 3. Isolation of recombinant influenza viruses under simulated conditions of natural transmission

Recombination between influenza A viruses from man and pigs and from chickens and turkeys was demonstrated under experimental conditions of natural transmission. The viruses were allowed to spread naturally from infected to contact animals, and recombinant viruses present in the contact animals were studied. In all experiments recombinant viruses were detected in the contact animals. The percentage of contact animals with recombinant viruses varied; it was as high as 50% in one experiment, and in another, the recombinants were the predominant type of virus present.Recombinants isolated from turkeys infected with fowl plague virus and turkey/Wisconsin/66 influenza virus or from turkeys infected with turkey/Ontario/7732/66 and turkey/Wisconsin/66 influenza virus always possessed the hemagglutinin subunit of the virulent parent. Thus, recombinant viruses possessing T/Ont_(H)-T/Wis_(N) or FPV_(H)-T/Wis_(N) were isolated and were highly virulent and genetically stable. The reciprocal recombinants were never isolated. In experiments with Hong Kong influenza virus and swine influenza virus in pigs, both kinds of recombinants were isolated [HK_(H)-SW_(N); SW_(H)-HK_(N)] and both of the recombinant viruses were genetically stable and caused mild infections in pigs.These studies provide experimental evidence that recombination can occur between influenza viruses from man and lower animals under simulated conditions of natural transmission in vivo and may offer an explanation for the origin of new strains of pandemic influenza viruses.     

Comparison of the 35S-methionine oligopeptide maps of influenza A virus NP proteins

Tryptic mapping of radioactive methionine-labeled NP proteins of 15 species of human influenzae A viruses and 11 animal viruses was performed. On the basis of similarities and differences of peptide maps, NP proteins were divided into 4 groups designated A, B, C, and D. Group A included viruses A/WS/33 and A/PR/8/34; Group B viruses H1N1 (apart from those isolated after 1977 and WSN virus), H2N2, H3N2, and 8 species of animal influenza viruses, Group C 4 species of H1N1 viruses isolated in 1977-1979 (A/USSR/90/77, A/USSR/086/79, A/USSR/093/79, A/Brazil/79); Group D three species of animal influenza viruses (A/swine/Iowa/30, A/horse/Praha/56, A/duck/England/56).     

Characteristics of the ribonucleoprotein of influenza virus A

Ribonucleoproteins (RNP) of influenza viruses A/Singapore/1/57, A/Victoria/35/72 and those isolated in the course of passaging in persistent infection systems (influenza virus--diploid human lung cells) were subjected to desimentation analysis. In viruses of different antigenic structure the 3 RNP fragments had the same sedimentation coefficients (63, 53, and 42 S, respectively). The ratios of RNP fragment concentrations had an individual character and were in relation with the antigenic differences between the strains studied.     

Evolution of the NS genes of the influenza a viruses. I. The genetic relatedness of the NS genes of animal influenza viruses

We compared the nucleotide sequences of the NS genes of 13 animal influenza viruses belonging to human, swine, avian, and equine viruses for the study of the genetic relatedness of the NS genes in animal influenza viruses. The NS genes of three virus strains A/chicken/Brescia/02, A/equine/Prague/56, and A/equine/Miami/63 were newly sequenced. The base sequence homologies between the NS genes of avian, human, swine, and the A/equine/Miami/63 viruses were 87.8% or higher. On the other hand, the base sequence of the NS gene of the A/equine/Prague/56 virus differed widely from those of other viruses analyzed in the present study. We constructed a model of the genetic tree of the NS genes of avian and equine influenza viruses by a modified Farris method (1). For comparison of the NS genes between human and avian viruses, we estimated the speed of the nucleotide substitutions of the avian influenza NS genes. It was roughly constant, even though the substitutions did not occur sequentially. The nucleotide substitution rate of the NS genes of avian influenza viruses was one-third to one-fourth that of human influenza viruses. We deduced the time of separation between the NS genes of human and avian influenza viruses during evolution.     

Evaluation of the Single Radial Hemolysis Test for Measuring Hemagglutinin- and Neuraminidase-Specific Antibodies to H3N2 Influenza Strains and Antibodies to Influenza B

Antibodies to the H3 hemagglutinin of influenza A virus could be specifically measured by single radial hemolysis (SRH) when test antigens were recombinant viruses containing the relevant H3 hemagglutinin antigen and irrelevant Neq1 neuraminidase of A/equine/Prague/1/56 virus. Antibodies to influenza B virus could also be measured by the SRH technique. Antibody rises to influenza A or B virus measured by SRH agreed with results of hemagglutination inhibition (HI) tests for about 80% of the sera tested, including sera from volunteers receiving killed influenza vaccine and sera from patients naturally infected with influenza. Correlation between antibody titers measured by SRH and HI was also good. Antibodies to the N2 neuraminidase of influenza A virus could be specifically measured by SRH when test antigens were recombinant viruses containing the relevant N2 neuraminidase antigen and irrelevant Heq1 hemagglutinin of A/equine/Prague/1/56 virus. The SRH test for neuraminidase antibodies was more strain specific than was the SRH test for hemagglutinin antibodies. Probably for this reason, agreement between neuraminidase antibody determinations in human sera by the SRH test and by the neuraminidase inhibition test was poorer than agreement between the SRH test for hemagglutinin antibodies and the HI test.     

Circulation of classical swine influenza virus in Europe between the wars?

The complete genomes of two swine influenza viruses from England were sequenced. Phylogenetic analysis revealed classical swine H1N1 viruses, one of which, A/swine/London, is closely related to virus strains of the early 1930s. Both strains are also antigenically related to A/swine/Iowa/15/1930, the strain originally isolated by Richard Shope. The source of A/swine/London is unknown, but its relationship to early classical swine influenza viruses suggests that the emergence of these viruses in Europe has to be antedated by 15-20 years.     

Determination of the antigenic composition of the hemagglutinins of influenza viruses H1N1

A comparative immunological analysis of the antigenic composition of hemagglutinins (HA) of influenza A viruses isolated from man and animals was done by the method of specific adsorption of immunoglobulin fractions recovered from sera of rabbits and rats immunized with influenza H1N1 viruses isolated in 1930-1948. A single determinant which remains antigenically stable from 1930 up to the present time was found in HA of human influenza H1N1 viruses (1933-1957, 1977-1981), swine virus A/Swine/Iowa/30, and whale virus A/whale/Pacific Ocean/8/76. Animal influenza viruses A/swine/Iowa/30 and A/whale/Pacific Ocean/8/76 have in their HA one more determinant contributing to the similarity of the swine virus with human A/PR8/34 virus, and the whale virus with human A/W.Smith/33 virus.     

Area under the curve calculations as a tool to compare the efficacy of equine influenza vaccines--a retrospective analysis of three independent field trials

Using the area under the curve (AUC) concept as is commonly used in pharmaceutical bioequivalence studies, the bioequivalence of three equine influenza vaccines was demonstrated. A retrospective analysis was performed using this technique on data generated in three trials in which each of the three vaccines had been used. In total, data from 63 pony and horse foals were used. The AUC of the single radial hemolysis (SRH) titres against Influenza A/equi-1/Prague/56 (Pr/56), A/equi-2/Newmarket-1/93, and A/equi-2/Suffolk/89 (Suf/89) were calculated for each horse. It was concluded that calculation of the AUC from four time-points permitted a suitable estimate for vaccine potency. Using pooled data, it appeared that the AUC permitted better evaluation of vaccine potency than simply considering the highest post vaccinal titre (Titremax). In two studies, a minimal value for the AUC was associated with protection against Influenza (H3N8) challenge 50-153 days later.     

Antiviral action of swine leukocyte interferon in mouse experiments

Swine leukocytes had previously been found to produce interferon which has an antiviral effect not only in swine cells but also in human cells. Preliminary experiments in tissue cultures showed the culture of primarily trypsinized mouse embryo fibroblasts to be as sensitive to swine interferon as human diploid cells. The experiment studying the antiviral effect of swine leukocyte interferon in the animals demonstrated it to protect mice against the pathogenic A/Aishi/68 (H3N2) strain; with a reduction of virus doses to 10 the protective effect of swine interferon increased 2-fold as compared with the experiments using 100-1000 virus doses. Inhibition of virus reproduction in lung tissues of experimental mice inoculated with A/Moscow/23/78 (H1N1), A/Wisconsin/19/67 (Hsw1N1) and A/Aishi/68 (H3N2) strains as compared with the controls. The experimental results suggest that the swine interferon produces the antiviral effect both in tissue culture and experimental animals.     

Genetic relatedness of the nucleoprotein (NP) of recent swine, turkey, and human influenza A virus (H1N1) isolates.

The sequences of nucleoprotein (NP) genes of recent human and turkey isolates of influenza A viruses, which serologically could be correlated to contemporary swine viruses, were determined. These sequences were closely related to the NPs of these swine viruses and they formed a separate branch on the phylogenetic tree. While the early swine virus from 1931 resembled the avian strains in consensus amino acids of the NP and in its ability to rescue NP ts mutants of fowl plague virus in chicken embryo cells, the later strains on that branch were different: at 15 positions they have their own amino acids and they rescued the NP ts mutants only poorly. Of the NPs of the human New Jersey/76 isolates analysed, one clustered with the recent H1N1 swine viruses of the U.S.A., the other one with contemporary human strains. Since the NP is one of the main determinants of species specificity it is concluded that, although the H1N1 swine isolates from the U.S.A. form their own branch in the phylogenetic tree, they can be transmitted to humans and turkeys, but they do not spread further in these populations and so far have not contributed to human pandemics. It is not very likely that they will do so in future, since its branch in the phylogenetic tree develops further away from the human and avian branch.     

Studies on the origin of pandemic influenza: III. Evidence implicating duck and equine influenza viruses as possible progenitors of the Hong Kong strain of human influenza

Two strains of influenza virus isolated from horses and ducks in 1963, A/equine/Miami/1/63 (Heq2 Neq2) and A/duck/Ukraine/1/63 (Hav7 Neq2) were found to possess hemagglutinin subunits which cross-reacted in hemagglutination-inhibition and immunodiffusion tests with those of the Hong Kong strain of human influenza A/Hong Kong/1/68 (H3 N2).Peptide maps of the heavy polypeptide chains from the hemagglutinin subunits of these three strains showed a number of differences, but maps of the light chains were almost identical, indicating that the light polypeptide chains from the hemagglutinin subunits of these animal, avian and human viruses had practically the same amino acid sequence.One explanation of these results is that the three viruses arose, by genetic recombination, from a common ancestor.     

Genetic characterization of swine influenza viruses (H3N2) isolated from Minnesota in 2006–2007

Triple-reassortant (TR) H3N2 swine influenza viruses (SIV) are a major cause of respiratory disease in swine worldwide, causing considerable morbidity and mortality. Continuous surveillance of circulating SIV strains is imperative for effective control and prediction of new emerging strains with interspecies transmission potential. The current study characterized SIV isolates from commercial swine population in USA (2006–2007). Nine isolates were completely sequenced, and the molecular evolution of all gene segments was analyzed. Phylogenetic analysis of the nine H3N2 viruses indicated that these strains belonged to cluster-IV of the human/swine/avian TR genotype, grouping with H3N2 viruses of turkey origin, while forming a separate sub-lineage from those of human and avian origin strains. Ten amino acid changes were observed at the major antigenic sites of HA1 region compared to the cluster-III reference strain, with differences in glycosylation sites. All the nine strains were antigenically related to the cluster-IV turkey strain than the cluster-III reference strain. The results of this study suggest that contemporary TR H3N2 strains circulating in North America share the same genetic constellation, thus maintaining the gene pool without any further event of genetic reassortment unlike swine-origin pandemic strain A/California/04/2009/H1N1. These findings strongly support the need for continuous surveillance and monitoring of genetic changes in SIV, to identify evolving strains that might pose a threat to human or animal health.     

Effects of streptovirudin on influenza viruses type A and B: inhibition of the lipid-linked oligosaccharide synthesis of fowl plague virus

Antibiotics of the streptovirudin complex (SV) inhibited the growth of influenza A and B viruses such as influenza A/fowl plague virus (FPV), strain Weybridge (Hav1 Neq1), influenza A/England 42/72 (H3N2), influenza A/Port Chalmers 1/73 (H3N2), influenza B/Leningrad 235/74, influenza B/Tokyo 7/66, and influenza B/Jamagata in chick embryo cell (CEC) cultures, in permanent canine kidney cells (MDCK), and in suspended fragments of chick embryo chorioallantoic membranes (CAM). As revealed by spectrophotometric turbidity measurements, SV completely inhibited the FPV-induced cytopathic effect (CPE). A 99.99% reduction of infectious virus yield was obtained in one-step growth cycle experiments and in the plaque reduction test. The haemagglutination inhibition titres of influenza viruses in suspended CAM fragment cultures in the presence of SV drugs were also substantially reduced. The incorporation assays indicated that SV exhibited no effect on virus-induced RNA synthesis, but influenced virus maturation by inhibition of lipid-linked oligosaccharide synthesis. A partial protection from infection was found in influenza virus A/England infected mice.     

Isolation of an influenza A virus from seals

Summary Influenza A virus of serotype Hav1 Neq1 (H7N7 by the 1980 revised influenza typing system proposed by WHO experts) was repeatedly isolated from lung and brain tissues taken from harbor seals (Phoca vitulina) found suffering from pneumonia on Cape Cod Peninsula (U.S.A.) in the winter of 1979–1980. The seal isolates, although of a serotype identical to some fowl plague virus strains, were harmless to chickens and turkeys in transmission experiments. An earlier human infection by a Hav1 Neq1 influenza virus and the serologic relatedness of this avian serotype with the equine 1 serotype are cited in support of the view that influenza viruses with these antigenic characteristics seem to have a facility to pass from birds to mammals.     

不同亚型禽流感病毒红细胞凝集特性分析

目的:了解不同亚型禽流感病毒与不同动物来源红细胞的凝集特性,为流感环境样本监测工作选择更适宜的检测用红细胞。方法:选取2009-2016年我国禽流感环境监测中分离到的不同亚型的禽流感毒株,采用红细胞凝集试验,选用5种动物红细胞(鸡、火鸡、豚鼠、马和绵羊)进行检测;应用流式细胞仪检测不同动物红细胞表面唾液酸受体的表达及类...     

Laboratory characterization of a swine influenza virus isolated from a fatal case of human influenza.

A swine influenza virus-like type A (H1N1) virus, designated A/Wisconsin/3523/88, was isolated in September 1988 from a Wisconsin woman who had died with primary viral pneumonia. Antigenic analyses with hemagglutinin-specific monoclonal antibodies and postinfection ferret serum indicated that the hemagglutinin of A/Wisconsin/3523/88 was antigenically closely related to viruses currently circulating in swine. Genetic analysis of the A/Wisconsin/3523/88 virus by RNA fingerprinting and partial RNA sequence analysis of seven of the eight segments indicated that the genome of the human isolate was similar to that of enzootic swine viruses. These laboratory data supported the epidemiologic findings that this human infection occurred by transmission of an enzootic swine influenza virus and that the virus showed no major genetic changes potentially related to increased pathogenesis.     

The prevalence of influenza viruses in swine and the antigenic and genetic relatedness of influenza viruses from man and swine.

Serological and virological surveillance of swine during 1976-77 showed that Hsw1N1 influenza viruses were prevalent throughout the swine population of the U.S., particularly in the northern states. A low incidence of H3N2 virus infections was detected serologically in pigs and confirmed by the isolation of a virus antigenically similar to A/Vic/3/75 from one herd. Both the hemagglutinin and neuraminidase antigens of the human New Jersey isolate, A/NJ/8/76, were indistinguishable from those of selected Hsw1N1 influenza viruses isolated from pigs from 1970 to 1977 and from man in 1976; these antigenically similar viruses were serologically separable from earlier swine viruses. The RNAs from Hsw1N1 viruses were separated by polyacrylamide-gel electrophoresis and the RNA migration patterns among viruses from both species were noticeably different. The only viruses with identical RNA migration patterns were human and swine isolates from the same farm in Wisconsin.