Serological evidence of hantavirus infections in Malaysia

Hantaviruses are primarily rodent-borne and transmission is by inhalation of virus-contaminated aerosols of rodent excreta, especially urine and saliva. The genus Hantavirus, family Bunyaviridae, comprises at least 14 serotypes and the symptoms of clinical illness range from mild fever to severe hemorrhagic manifestations with renal complications. Many countries in Southeast Asia are unaware of the importance of hantavirus infections and give them low priority. Malaysia, like other countries in the region, has conducted very few studies on the epidemiology of hantaviruses - and even these were conducted in the 1980s. Using a more extensive range of hantavirus antigens, we conducted a seroprevalence study of rodents and humans and found further evidence of hantavirus infections. Moreover, the data from the antibody profiles strongly suggest the presence of different hantaviruses at the study sites.

Genetic analysis of an influenza B virus isolated from a patient with encephalopathy in Japan

An influenza B virus, B/Saga/S172/99 (SAG99), was isolated from the nasopharynx of a patient with encephalopathy/encephalitis in Japan in 1999. To clarify the molecular characteristics of this virus, detailed analysis of the gene segments coding for the hemagglutinin (HA), neuraminidase (NA), nucleoprotein (NP), matrix protein (M) and non-structural protein (NS) was undertaken. All five genes of SAG99 showed high nucleotide and predicted amino acid similarities with those of recent non-encephalopathic strains isolated in the same epidemic season. Subsequent phylogenetic analysis revealed that all five gene segments of SAG99 analyzed in the present study were most similar to those of the recent Yamagata/16/88-like viruses. The hemagglutinin and neuraminidase proteins of SAG99 were each distinguished from those of recent epidemic strains by one characteristic amino acid substitution. These substitutions were not found in the previously reported encephalopathy/encephalitis-derived influenza B viruses, and we could not find any common characteristic amino acid changes in SAG99 and these viruses. Similarly, among the internal proteins studied, only the M2 protein of SAG99 was found to contain a single novel amino acid change when compared with other recent isolates. Thus, it was apparent that SAG99 contained very few amino acid differences when compared with other epidemic viruses. The association of recent B/Yamagata/16/88-like viruses with encephalitis/encephalopathy observed in the present study and previously suggest that these viruses may have a higher potential for causing neurological complications in certain individuals.

Synthesis of 6-acetamido-5-amino- and -5-guanidino-3, 4-dehydro-N-(2-ethylbutyryl)- 3-piperidinecarboxylic acids related to zanamivir and oseltamivir, inhibitors of influenza virus neuraminidases

[reaction: see text] 6-Acetamido-5-amino- and -5-guanidino-3, 4-dehydro-N-(2-ethylbutyryl)-3-piperidinecarboxylic acids (8 and 9) have been synthesized starting from natural siastatin B, a bacterial neuraminidase inhibitor isolated from Streptomyces culture in a stereospecific fashion. These compounds are related to zanamivir and oseltamivir, inhibitors of influenza virus neuraminidases.

Characterization of low virulent strains of highly pathogenic A/Hong Kong/156/97 (H5N1) virus in mice after passage in embryonated hens' eggs

Avian influenza A H5N1 viruses were isolated from humans for the first time in Hong Kong in 1997. The virulence of A/Hong Kong/156/97 (HK156) strain in mice was found to change significantly depending on the passage history of the virus. Madin-Darby canine kidney (MDCK) cell-grown parental virus and three of its clones derived from mouse brain showed high pathogenicity in mice after intranasal or intracerebral infection. In contrast, the egg-derived parental virus HK156-E3 and its cloned viruses were markedly less pathogenic in mice. It appeared that differences in pathogenicity among viruses derived from MDCK cells and eggs were due to their ability or inability to disseminate from the lungs to the brain. Sequence analysis of the entire protein coding regions of all eight RNA genome segments revealed a total of six conserved amino acid differences in the HA1 domain (residue 211) of the HA protein, as well as the PB1 (residues 456 and 712), PA (residue 631), NP (residue 127), and NS1 (residue 101) proteins that correlated with observed changes in virulence and neurovirulence of HK156 virus in mice. Thus it was evident that the passaging of HK156 in embryonated eggs led to the adaptation and selection of variants demonstrating markedly decreased pathogenicity and neurovirulence in mice that appeared to be attributable to specific amino acid changes in the HA and internal proteins.

Evolutionary characterization of the six internal genes of H5N1 human influenza A virus

The entire nucleotide sequences of all six internal genes of six human H5N1 influenza A viruses isolated in Hong Kong in 1997 were analysed in detail from a phylogenetic point of view and compared with the evolutionary patterns of the haemagglutinin and neuraminidase genes. Despite being isolated within a single year in the same geographical location, human H5N1 viruses were characterized by a variety of amino acid substitutions in the ribonucleoprotein complex [PB2, PB1, PA and nucleoprotein (NP)] as well as the matrix (M) proteins 1 and 2 and nonstructural (NS) proteins 1 and 2. The presence of previously reported amino acid sequences specific for human strains was confirmed in the PB2, PA, NP and M2 proteins. Nucleotide and amino acid sequence identities of the six internal genes of H5N1 viruses examined here were separated into at least two variant groups. In agreement with the above result, phylogenetic trees of the six internal genes of human H5N1 viruses were generally composed of two minor clades. Additionally, variable dendrogram topologies suggested that reassortment among viruses contributed further to the genetic variability of these viruses. As a result, it became clear that human H5N1 viruses are characterized by divergent gene constellations, suggesting the possible occurrence of genetic reassortment between viruses of the two evolutionary lineages.

In vitro growth profiles of respiratory syncytial virus in the presence of influenza virus

To elucidate epidemiological interference between respiratory syncytial (RSV) and influenza viruses, the influence of influenza A (HlN1) virus on the growth of RSV was examined. Although RSV grew in MDCK cells, coinfection with influenza A virus led to a reduction of progeny RSV. The degree of growth interference depended on the time of infection with influenza A virus post infection (p.i.) with RSV. In fact, infection with influenza A virus 12 hrs p.i. with RSV did not influence growth of the latter virus. On the contrary, growth suppression of influenza A virus by RSV was observed when the coinfection began at the later stages of RSV infection. Suppression of the growth of RSV by influenza A infection was further demonstrated at the level of viral protein synthesis. An indirect immunofluorescence (IF) test revealed that a large proportion of infected cells synthesized both RSV and influenza A virus antigens. Scanning electron microscopic (SEM) examination demonstrated that influenza A and RSV virions possessing surface antigens specific for each virus were selectively released from dually infected cells. In the present study, we proved for the first time that the growth of RSV is blocked by competitive infection with influenza A virus in a susceptible cell population, competitive protein synthesis and selective budding of RSV and influenza viruses from the same infected cells.

Phylogenetic analysis of the three polymerase genes (PB1, PB2 and PA) of influenza B virus

Phylogenetic patterns of the three polymerase (PB2, PB1 and PA) genes of a total of 20 influenza B viruses isolated during a 58 year period, 1940-1998, were analysed in detail in a parallel manner. All three polymerase genes consistently showed evolutionary divergence into two major distinct lineages and their amino acid profiles demonstrated conserved lineage-specific substitutions. Dendrogram topologies of the PB2 and PB1 genes were very similar and contrasted with that of the PA gene. It was of particular interest to reveal that even though the PA gene evolved into two major lineages, that of three recent Asian Victoria/1/87-like strains formed a branch cluster located in the same lineage as that of recent Yamagata/16/88-like isolates. Differences in the phylogenetic pathways of three polymerase genes were not only a reflection of genetic reassortment between co-circulating influenza B viruses, but also an indication that the polymerase genes were not co-evolving as a unit. As a result, comparison of the phylogenetic patterns of the three polymerase genes with previously determined patterns of the HA, NP, M and NS genes of 18 viruses defined the existence of eight distinct genome constellations. Also, similar phylogenetic profiles among the PA, NP and M genes, as well as between the PB2 and PB1 genes, were observed, suggesting possible functional interactions among these proteins. Completion of evolutionary analysis of the six internal genes and the HA gene of influenza B viruses revealed frequent genetic reassortment among co-circulating variable strains and suggested co-dependent evolution of genes.

Safety and efficacy of the neuraminidase inhibitor zanamivir in treating influenza virus infection in adults: results from Japan. GG167 Group

The study was carried out to evaluate the therapeutic effects of zanamivir, a highly selective, potent and specific inhibitor of influenza A and B virus neuraminidases, in adult patients with acute influenza-like illness. Patients who presented within 36 h of the onset of influenza-like symptoms were randomly assigned to receive one of three treatments, twice daily, for 5 days: 10 mg zanamivir powder for inhalation (zanamivir inhalation group), 10 mg zanamivir powder for inhalation plus 6.4 mg zanamivir nasal spray (zanamivir inhalation plus intranasal group) or placebo (placebo group). The primary end point was the time to alleviation of the three major symptoms (fever, headache and myalgia). The secondary end point was the time to alleviation of five influenza symptoms (fever, headache, myalgia, cough and sore throat). One hundred and sixteen patients with influenza-like illness were recruited to the study. No differences were observed between the two groups of patients who received zanamivir (inhalation group or inhalation plus intranasal group). Patients who received zanamivir recovered significantly faster (median 3 days to recovery) than the patients in the placebo group (median 4 days to recovery; P < 0.01). Topically administered zanamivir was well tolerated. This study confirms that in adults, topically administered zanamivir is well tolerated and is effective in reducing the time to alleviation of influenza symptoms.

Evaluation of immune responses to inactivated influenza vaccines prepared in embryonated chicken eggs and MDCK cells in a mouse model

This study was initiated with the isolation of influenza A and B viruses from clinical throat swabs in both fertile chicken eggs (egg) and MDCK cells, which were used in subsequent vaccine production in the above two hosts. On the basis of haemagglutination-inhibiting (HI) tests, immune mouse sera from mice vaccinated with MDCK cell-derived vaccines revealed antigenic similarities among H3N2 or B viruses isolated in MDCK cells or eggs. Similarly, antiserum prepared by immunization with egg-derived H3N2 vaccine showed equivalent antigenicity between homologous and heterologous (MDCK cell-derived) viruses. In contrast, antigenicity of egg-derived B vaccines was differed somewhat from that of MDCK cell-derived vaccines, suggesting the occurrence of antigenic change due to passaging in eggs. The time-course of immune responses based on HI titres indicated that MDCK cell-derived vaccines elicited extremely high antibody levels. Also, it was evident that antibody production by MDCK cell-grown H3N2 vaccine was very similar to that of vaccine prepared from egg-grown viruses. These results were comparable to those of plaque neutralization tests, although antigenic differences between egg- and MDCK cell-derived challenge viruses were confirmed in the test with antiserum to MDCK cell-derived vaccine. Consistent with HI-antibody production, the immunogenicity of MDCK cell-derived B vaccine appeared to be low by plaque neutralization test, while immune responses in mice which received egg-derived vaccines were significantly higher than that of the former. Furthermore, immune responses confirmed in mice immunized with B virus vaccines prepared in eggs revealed slight antigenic differences between two viruses derived from their respective hosts. Nevertheless, through evaluation of immune responses, MDCK cell-derived influenza vaccines may be useful when weak immunogenicity of B virus vaccine is improved.

Recombinant vaccinia viruses expressing an immunodominant epitope of HIV-1 envelope protein within an influenza hemagglutinin cassette predominantly prime epitope-specific CD8(+) CTL

We constructed recombinant vaccinia viruses (RVV) expressing a 15-residue peptide (P18IIIB; RIQRGPGRAFVTIGK) of gp160 envelope protein from a human immunodeficiency virus type-1 (HIV-1) IIIB isolate using an H1 influenza virus hemagglutinin (HA) gene cassette. Immunofluorescent tests with antisera against both H1N1 influenza virus and P18IIIB localized chimeric HA molecules comprising influenza virus HA and P18IIIB peptide intracellularly, but the P18IIIB could not be seen on the outer surfaces of infected cells though weak fluorescence was detected regarding HA molecule. Consistent with these findings, Western blotting confirmed the expression of a polypeptide of about 74-kDa protein representing chimeric HA molecule in the infected cells. These recombinants markedly primed CD8(+) cytotoxic T lymphocytes (CTL) specific for P18IIIB as well as HA protein of the influenza virus, but failed to elicit P18IIIB-specific antibody despite stimulating production of HA-specific antibody. In addition, the P18IIIB-specific CTL could strongly lyse target cells expressing the whole HIV-1 envelope gene of IIIB strain. Thus, the influenza virus chimeric HA cassette vector system used in the present study appeared to be a useful tool for constructing vaccine candidates which will predominantly prime CD8(+) CTL specific for immunodominant determinants of various infectious agents.

Two outbreaks of influenza A (H3N2) in a Japanese nursing home in the winter of 1996-1997, with differing vaccine efficacy

Sixty of 128 (46.9%) residents of a nursing home were immunized with two doses of the trivalent split influenza vaccine. They developed 7.4-11.5-fold antibody increases, with a 69-82% protection rate, presenting good immune response rates to the influenza vaccine. Two outbreaks of influenza A (H3N2) occurred. There were no significant antigenic differences among the vaccine strain and the strains isolated from both outbreaks in haemagglutination-inhibition tests, suggesting that the second might have been a reoccurrence. There were no residents who were infected in both outbreaks. The vaccine efficacy against clinical illness in the first outbreak of typical influenza-like-illness (ILI) was 51% (relative risk: 0.49), and the febrile period was reduced significantly by vaccination. In the second outbreak, however, in which all patients had atypical ILI with a high fever but not respiratory symptoms, vaccine efficacy was not apparent for unknown reason.

Comparative analysis of evolutionary mechanisms of the hemagglutinin and three internal protein genes of influenza B virus: multiple cocirculating lineages and frequent reassortment of the NP, M, and NS genes

Phylogenetic profiles of the genes coding for the hemagglutinin (HA) protein, nucleoprotein (NP), matrix (M) protein, and nonstructural (NS) proteins of influenza B viruses isolated from 1940 to 1998 were analyzed in a parallel manner in order to understand the evolutionary mechanisms of these viruses. Unlike human influenza A (H3N2) viruses, the evolutionary pathways of all four genes of recent influenza B viruses revealed similar patterns of genetic divergence into two major lineages. Although evolutionary rates of the HA, NP, M, and NS genes of influenza B viruses were estimated to be generally lower than those of human influenza A viruses, genes of influenza B viruses demonstrated complex phylogenetic patterns, indicating alternative mechanisms for generation of virus variability. Topologies of the evolutionary trees of each gene were determined to be quite distinct from one another, showing that these genes were evolving in an independent manner. Furthermore, variable topologies were apparently the result of frequent genetic exchange among cocirculating epidemic viruses. Evolutionary analysis done in the present study provided further evidence for cocirculation of multiple lineages as well as sequestering and reemergence of phylogenetic lineages of the internal genes. In addition, comparison of deduced amino acid sequences revealed a novel amino acid deletion in the HA1 domain of the HA protein of recent isolates from 1998 belonging to the B/Yamagata/16/88-like lineage. It thus became apparent that, despite lower evolutionary rates, influenza B viruses were able to generate genetic diversity among circulating viruses through a combination of evolutionary mechanisms involving cocirculating lineages and genetic reassortment by which new variants with distinct gene constellations emerged.

Phylogenetic analysis of the entire genome of influenza A (H3N2) viruses from Japan: evidence for genetic reassortment of the six internal genes

Nucleotide sequences of all eight RNA segments of 10 human H3N2 influenza viruses isolated during a 5-year period from 1993 to 1997 were determined and analyzed phylogenetically in order to define the evolutionary pathways of all genes in a parallel fashion. It was evident that the hemagglutinin and neuraminidase genes of these viruses evolved essentially in a single lineage and that amino acid changes accumulated sequentially with respect to time. In contrast, amino acid differences in the internal proteins were erratic and did not accumulate over time. Parallel analysis of the phylogenetic patterns of all genes revealed that the evolutionary pathways of the six internal genes were not linked to the surface glycoproteins. Genes coding for the basic polymerase-1, nucleoprotein, and matrix proteins of 1997 isolates were closest phylogenetically to those of earlier isolates of 1993 and 1994. Furthermore, all six internal genes of four viruses isolated in the 1995 epidemic season consistently divided into two distinct branch clusters, and two 1995 isolates contained PB2 genes apparently originating from those of viruses before 1993. It was apparent that the lack of correlation between the topologies of the phylogenetic trees of the genes coding for the surface glycoproteins and internal proteins was a reflection of genetic reassortment among human H3N2 viruses. This is the first evidence demonstrating the occurrence of genetic reassortment involving the internal genes of human H3N2 viruses. Furthermore, internal protein variability coincided with marked increases in the activity of H3N2 viruses in 1995 and 1997.

Phylogenetic analyses of the matrix and non-structural genes of equine influenza viruses

Matrix (M) and nonstructural (NS) genes of thirteen equine H3N8 and H7N7 influenza viruses were sequenced and analyzed from an evolutionary point of view. The M and NS genes of H3N8 viruses isolated between 1989 and 1993 evolved into two minor branch clusters, including isolates from Europe and the American continent, respectively. It was noteworthy to reveal that the nucleotide sequences of the M and NS genes of an earlier American strain showed highest homology to those of recent European viruses. "Frozen evolution" was observed in the M and NS genes of A/eq/LaPlata/1/88. It was also evident that the NS gene of an H7N7 virus from 1977 was very similar to that of a 1979-H3N8 virus, while the M gene was closest phylogenetically to that of the earliest H7N7 virus isolated in 1956. Furthermore, the M2 protein of A/eq/Newmarket/1/77 virus contained a carboxyl terminal deletion of three amino acids. The evolutionary rates of the M and NS genes of H3N8 equine influenza viruses were estimated to be 5.4 x 10(-4) and 5.1 x 10(-4) substitutions per site per year, respectively, which were slower than those of human viruses.

Evolutionary characteristics of influenza B virus since its first isolation in 1940: dynamic circulation of deletion and insertion mechanism

New antigenic variants of B/Yamagata/16/88-like lineage which appeared in the season of 1997 as a minor strain tended to predominate in the following season. Also, we could observe for the first time, three peaks of activity caused by H3N2 virus and two variants of B influenza virus. Antigenic and phylogenetic analyses revealed that B/Victoria/2/87-like variants appeared again in Japan in 1997 after a nine-year absence. Influenza B viruses evolved into three major lineages, including the earliest strain (I), B/Yamagata/16/88-like variants (II), which comprised of three sublineages (II-(i), II-(ii), II-(iii)), and B/Victoria/2/87-like variants (III). Evolution of influenza B virus hemagglutinin was apparently distinguishable from that of influenza A virus, showing a systematic mechanism of nucleotide deletion and insertion. This phenomenon was observed to be closely related to evolutionary pathways of I, II-(i), II-(ii), II-(iii) and III lineages. It was noteworthy to reveal that the nucleotide deletion and insertion mechanism of influenza B virus completed one cycle over a fifty-year period, and that a three nucleotide deletion was again observed in 1997 strains belonging to lineage II-(iii). It was evident that amino acid substitutions accompanying nucleotide insertions were highly conserved.

[Acute encephalitis and encephalopathy at the height of influenza in childhood]

Twenty six infants and children with acute encephalitis and encephalopathy during two influenza seasons in Hokkaido, the northernmost island of Japan, were reported. Thirteen patients died and 5 had residual neurological sequelae. Influenza virus genome was detected by PCR in 9 out of 10 cerebrospinal fluid samples from these patients. CT and MRI of the brain demonstrated symmetrical changes in the thalamus and brainstem. The prevalence of these encephalitis and encephalopathy of childhood should be surveyed by nationwide scale.

Large sequential outbreaks caused by influenza A (H3N2) and B viruses in an institution for the mentally handicapped

During the mixed epidemic caused by influenza A (H3N2) and B in the 1992-1993 season in Japan, large sequential outbreaks occurred in an institution for mentally handicapped people where none of the residents or staff members had been immunized. During the influenza A outbreak (A/ Beijing/32/92-like strain) in January, 37.0% of the residents (85/230) and 31.4% of the staff (75/239) had an influenza-like illness. During the influenza B outbreak (B/Panama/45/90- and B/Beijing/184/ 93-like strain) in late February, 59.0% of the residents and 24.3% of the staff had an influenza-like illness. As many as 25.2% of the residents had two episodes of influenza-like illness during the season, as opposed to only 5.4% of the staff members. Mixed epidemics probably have a severe impact on institutionalized high-risk people, adversely affecting them almost twice as much as influenza epidemics caused by a single virus.

Maturation of respiratory syncytial virus within HEp-2 cell cytoplasm

Electron microscopy of HEp-2 cells infected with respiratory syncytial virus (RSV) strain Long revealed the maturation of RSV on an ultrastructural level. The results showed that the virus maturated by two different pathways. In one of them, the virus assembled and matured before reaching the plasma membrane on the internal vesicle membrane within cytoplasm. The mature virus was delivered to the plasma membrane and to the extracellular space most likely by the transport vesicles and exocytosis. In the other pathway, the virus matured on the plasma membrane as described with other members of the family Paramyxoviridae. Using monoclonal antibodies (MoAbs), we localized viral nucleoprotein (NP) and envelope proteins in cytoplasm by immunoelectron microscopy (IEM).

Large outbreak of swine influenza in southern Japan caused by reassortant (H1N2) influenza viruses: its epizootic background and characterization of the causative viruses

In the winter of 1989 and the spring of 1990, there were large outbreaks of respiratory disease in two swine herds in Nagasaki Prefecture, southern Japan. Serological surveillance indicated that the majority of swine possessed antibodies to swine influenza virus H1 haemagglutinin and neuraminidase of early H3N2 influenza virus strains. Eight viruses were isolated from swine that showed typical clinical symptoms of influenza. The haemagglutinin and neuraminidase of these isolates were closely related to those of swine H1N1 and early human H3N2 viruses, respectively. At least two types of haemagglutinin antigens, distinguished by two monoclonal antibodies, were involved in the outbreaks. Evolutionary analyses indicated that the haemagglutinin gene of the H1N2 reassortants was closely related to those of a recent swine lineage (A/sw/HK/1/74 and A/sw/Ehime/1/80 viruses). However, the neuraminidase genes of the H1N2 reassortants were similar to those of swine N2 viruses which in turn are related to early human H3N2 viruses. A comparison of partial nucleotide sequences revealed that the six other genes of A/sw/Nagasaki/1/89 were derived from those of swine H1N1 virus.

Evolutionary characterization of recent human H3N2 influenza A isolates from Japan and China: novel changes in the receptor binding domain

Recent human H3N2 influenza viruses isolated in Japan and China were characterised from an evolutionary point of view. They appeared to have divided into three minor branch clusters, including 1992-1993, 1993-1994 and 1994-1995 isolates. It was of particular interest to reveal that in addition to amino acid substitutions in the antigenic sites of the HA molecule, amino acid changes occurred at position 226 of the receptor binding site from lysine or glutamine to isoleucine in all strains belonging to the 1994-1995 branch cluster. This is the first evidence of human H3N2 influenza isolates, or any other influenza HA serotypes, to contain a conserved amino acid residue other than lysine or glutamine at this key position.

In vivo induction of cytotoxic T lymphocytes specific for a single epitope introduced into an unrelated molecule

Cytotoxic T lymphocytes (CTLs) recognise antigenic peptides in the context of major histocompatibility complex (MHC) class I molecules on virus-infected cells. The formation and transportation of antigenic peptides to class I MHC in the cells are multi-step reactions known as antigen processing. In order to design a good DNA vaccine, it is important to dissect the specificity of antigen processing. Here we describe the construction of an epitope-based plasmid vector as a device to investigate antigen processing in transfected cells. The epitope-based plasmid vector was constructed by insertion of an epitope-encoding minigene into the lacZ gene. We used a CTL epitope on influenza A virus nucleoprotein (NP366-374 epitope) as a model. Upon transfection, the epitope-based plasmid vector induced the expression of NP epitope antigenically as well as immunogenically. Immunization of mice with plasmid-transfected cells was able to induce NP epitope-specific CTLs in vivo. Moreover, the plasmid vector functioned as a gene vaccine; NP epitope-specific CTLs were primed in vivo upon transfection of the vector into dermis by electroporation. The results suggest that this epitope-based DNA delivery system may provide a new strategy for in vivo induction of epitope-specific CTLs to investigate antigen processing and presentation.

Antigenic and genetic characteristics of H1N1 human influenza virus isolated from pigs in Japan

Two strains of influenza A virus were isolated from pigs in northern Japan in 1992. Serological tests showed that the haemagglutinin (HA) and neuraminidase (NA) antigens were more closely related to those of recent human H1N1 viruses than to those of swine H1N1 viruses. The HA and NA genes of isolate A/sw/Obihiro/5/92 were shown to be closely related to those of current human H1N1 viruses. Evolutionary trees constructed from nucleotide sequences showed that the HA and NA genes of A/sw/Obihiro/5/92 were apparently on a branch cluster containing human strains isolated between 1990 and 1992.

Genetic analysis of porcine H3N2 viruses originating in southern China

From immunological and phylogenetic analyses of H3 influenza viruses isolated from pigs and ducks in the People's Republic of China (China), Hong Kong, Taiwan and Japan, between 1968 and 1982, we arrived at the following conclusions. The H3 haemagglutinin and N2 neuraminidase genes from swine isolates can be segregated into four mammalian lineages, including: (i) the earliest human strains; (ii) early swine strains including Hong Kong isolates from 1976-1977; (iii) an intermediate strain between the early swine and recent human strains; and (iv) recent human strains. In this study we found an unusual swine strain (sw/Hong Kong/127/82) belonging to the third lineage which behaved like those of the early swine-like lineage in the haemagglutination inhibition test; but neuraminidase inhibition profiles with monoclonal antibodies indicated that this virus is related to late human strains. On the basis of pairwise comparisons of complete or partial nucleotide sequences the genes encoding the three polymerase proteins (PB2, PB1, PA), the nucleoprotein, the membrane protein and possibly the nonstructural proteins of sw/Hong Kong/127/82 are of the swine H1N1 lineage, whereas genes encoding the two surface glycoproteins belong to the human H3N2 lineage. In contrast, all RNA segments of one swine isolate (sw/Hong Kong/81/78) are similar to those of recent human H3N2 viruses. This study indicated that frequent interspecies infections between human and swine hosts appeared to occur during 1976-82. Although the evolutionary rates of human (0.0122/site/year), swine (0.0127/site/year) and avian (0.0193/site/year) virus genes are similar when based upon synonymous substitutions, nonsynonymous substitutions indicated that viral genes derived from human and swine viruses evolved about three times faster (0.0026-0.0027/site/year) than those of avian viruses (0.0008/site/year). Furthermore, the evolutionary mechanism by which human and swine H3 haemagglutinin genes evolve at a similar rate, based on nonsynonymous substitutions, appeared to be quite different from previous evidence which showed that human H1 haemagglutinin genes evolved three times faster than those of swine viruses. However, comparison of the number of nonsynonymous substitutions in the antigenic sites (A-E) of haemagglutinin molecules demonstrated that swine viruses evolve at a rate that is about one fifth to one tenth that of human viruses, reflecting the conservative nature of the antigenic structure in the former.

Characteristics of cytotoxic T lymphocytes directed to influenza virus haemagglutinin elicited by immunization with muramyldipeptide-influenza liposome vaccine

We examined the characterization of the antiviral T lymphocytes elicited by immunization with a novel liposome vaccine (MDP-virosome) constructed with synthetic muramyldipeptide; [6-0-(2-tetradecylhexadecanoyl)-N-acetylmuramyl-L-alanyl-D-isoglutamine] , cholesterol, influenza virus haemagglutinin and neuraminidase. The haemagglutinin glycoprotein first appeared to induce a significant subtype-specific cytotoxic activity through its arrangement on the inner and outer surfaces of the MDP-virosome. Splenocytes of BALB/c mice immunized with the virosome vaccine containing H3 haemagglutinin and N2 neuraminidase from human Hong Kong virus markedly lysed H3N2 virus-infected target cells, but not those infected with virus possessing a different subtype such as H1N1 surface antigens. Exposure of these splenic lymphocytes to virus antigen in vitro further enhanced their cytotoxic activity. The cytotoxic lymphocytes generated by the MDP-virosome vaccine expressed Thy 1 and CD4 antigens on their cell surface, and these activities were restricted by class II histocompatibility gene products. The marked reduction of pulmonary virus titres in infected mice caused by transferred immune spleen cells suggested that the MDP-virosome vaccination is able to protect against influenza virus infection through enhanced cellular immune responses.

Efficacy of inactivated vaccine in preventing antigenically drifted influenza type A and well-matched type B

OBJECTIVE

To evaluate the efficacy of currently used inactivated influenza vaccine during a severe epidemic caused by antigenically drifted influenza type A(H3N2) and well-matched type B viruses during the 1992-1993 season.

DESIGN

Prospective nonrandomized controlled trial.

SETTING

An urban general hospital pediatric asthma clinic in Japan.

PARTICIPANTS

A total of 137 children with moderate to severe asthma (mean age, 7.0 years; range, 2 to 14 years).

INTERVENTION

Eighty-five children received trivalent split-antigen vaccine containing A/Beijing/352/89 (H3N2) and B/Bangkok/163/90 (B/Panama/45/90-like strain). Fifty-two were unvaccinated.

MAIN OUTCOME MEASURES

Protection against infection was determined using hemagglutination inhibition test and virus isolation. Clinical efficacy was estimated based on febrile episodes with antibody rise or virus isolation.

RESULTS

Although marked antigenic drift in hemagglutinin was demonstrated in the epidemic virus (A/Beijing/32/92-like strain), the protection against influenza type A(H3N2) infection was 67.5% (P < .01). The protection against influenza type B infection was 43.7% (P < .01), although the epidemic influenza type B viruses were antigenically almost identical to the vaccine strain. Inactivated vaccine was not effective for protection against influenza type B infection in children younger than 7 years. High clinical effectiveness was demonstrated in children at least 7 years of age during the epidemic.

CONCLUSIONS

Our data suggest that current inactivated vaccine is highly effective for protection against influenza type A(H3N2) virus infection regardless of antigenic drift. In contrast, the protective efficacy obtained by vaccination may not be sufficient against influenza type B virus infection, and especially in young children, it does not offer protection.

Origin and evolutionary pathways of the H1 hemagglutinin gene of avian, swine and human influenza viruses: cocirculation of two distinct lineages of swine virus

The nucleotide sequences of the HA1 domain of the H1 hemagglutinin genes of A/duck/Hong Kong/36/76, A/duck/Hong Kong/196/77, A/sw/North Ireland/38, A/sw/Cambridge/39 and A/Yamagata/120/86 viruses were determined, and their evolutionary relationships were compared with those of previously sequenced hemagglutinin (H1) genes from avian, swine and human influenza viruses. A pairwise comparison of the nucleotide sequences revealed that the genes can be segregated into three groups, the avian, swine and human virus groups. With the exception of two swine strains isolated in the 1930s, a high degree of nucleotide sequence homology exists within the group. Two phylogenetic trees constructed from the substitutions at the synonymous site and the third codon position showed that the H1 hemagglutinin genes can be divided into three host-specific lineages. Examination of 21 hemagglutinin genes from the human and swine viruses revealed that two distinct lineages are present in the swine population. The swine strains, sw/North Ireland/38 and sw/Cambridge/39, are clearly on the human lineage, suggesting that they originate from a human A/WSN/33-like variant. However, the classic swine strain, sw/Iowa/15/30, and the contemporary human viruses are not direct descendants of the 1918 human pandemic strain, but did diverge from a common ancestral virus around 1905. Furthermore, previous to this the above mammalian viruses diverged from the lineage containing the avian viruses at about 1880.

[Electrophysiological evaluation of human consciousness level by "Automated Fluctuation Analysis" of human high frequency EEG]

This study is done to clarify the clinical meaning of "Automated Fluctuation Analysis" of high frequency EEG in man especially focused on the fine alteration of consciousness level of the subjects. Twenty normal volunteers were utilized for this study. They were divided into two groups, the subjects who felt sleepiness (Group S; N = 8) and the subjects who denied it (Group W; N = 12), during the EEG recording. "Automated Fluctuation Analysis" of high frequency EEG had been presented in our previous paper. In short, it is made of three steps, amplification of EEG signal, A/D conversion and Fast Fourier Transform by signal processor and extraction of Lorentzian parameters. Power spectral density (PSD) was displayed on log-log graph. Then the third step is performed by the best curve fitting program to the following equation, S (f) = S1/[1 + (f/fc1)2] + S2/ [1 + (f/fc2)2], where S(f) is power spectral density at any frequency f, S1 and S2 are plateau level of initial and second Lorentz, respectively and fc1 and fc2 are the corner or half power frequency of initial and second Lorentz, respectively. The algorithm of this program to extract these parameters were mathematically based on Brown & Dennis. As results, 1. PSD of human high frequency EEG was composed of double Lorentzians and vanished into white level within 1kHz. 2. A topographical display of S1 value revealed hyperfrontal in group W, which is in accordance with the cerebral blood flow study by Ingvar.(ABSTRACT TRUNCATED AT 250 WORDS)

Origin and evolutionary characteristics of antigenic reassortant influenza A (H1N2) viruses isolated from man in China

During the 1988/1989 influenza season, five antigenic reassortant influenza A (H1N2) viruses not previously isolated from man were isolated in Hebei province, People's Republic of China. All isolates contained haemagglutinins (HAs) and neuraminidases (NAs) which were antigenically similar to those of the recent Russian (H1N1) and Hong Kong influenza A (H3N2) viruses, respectively. The results of antigenic and nucleotide sequence analyses revealed that the genes encoding the polymerase, nucleoprotein, NA, matrix and non-structural proteins of the reassortant A/Hebei/24/89 (H1N2) virus were derived from the H3N2 parent virus, whereas its HA gene was from the H1N1 parent virus. The nucleotide sequences of the HA (encoding the HA1 subunit) and NA genes of the reassortant viruses were also determined. Phylogenetic trees constructed from these data by the neighbour-joining method revealed that the HA gene of the reassortant virus was closely related to those of recent human H1N1 viruses, whereas the NA gene was related to a recent human Hong Kong (H3N2) virus lineage.

Evolutionary pattern of the H 3 haemagglutinin of equine influenza viruses: multiple evolutionary lineages and frozen replication

The nucleotide and deduced amino acid sequences of the haemagglutinin genes coding for the HA 1 domain of H3N8 equine influenza viruses isolated over wide regions of the world were analyzed in detail to determine their evolutionary relationships. We have constructed a phylogenetic model tree by the neighbour-joining method using nucleotide sequences of 15 haemagglutinin genes, including those of five viruses determined in the present study. This gene tree revealed the existence of two major evolutionary pathways during a twenty five-year period between 1963 to 1988, and each pathway appeared to consist of two distinct lineages of haemagglutinin genes. Furthermore, our analysis of nucleotide sequences showed that two distinct lineages of equine H3N8 viruses were involved in an equine influenza outbreak during the period of December 1971-January 1972 in Japan. The number of nucleotide changes between strains was proportional to the length of time (in years) between their isolation except for three of the HA genes. However, there are three exceptional strains isolated in 1971, 1987, and 1988, respectively. The haemagglutinin gene in these strains showed a small number of nucleotide substitutions after they branched off around 1963, suggesting an example of frozen replication. Although the estimated rate (0.0094/site/year) of synonymous (silent) substitutions of the haemagglutinin gene of equine H3N8 viruses was nearly the same as that of human H 1 and H 3 haemagglutinin genes, the rate of nonsynonymous (amino-acid changing) substitutions of the former equine virus gene was estimated to be 0.00041/site/year--that is about 5 times lower than that estimated for the human H 3 haemagglutinin gene. The present study is the first demonstration that multiple evolutionary lineages of equine H3N8 influenza virus circulated since 1963.

Impact of influenza virus infection as a cause of pediatric hospitalization

From winter 1989 to spring 1990, a severe epidemic caused by influenza A (H3N2) and B viruses developed in Japan. During the epidemic (December 1989 to February 1990), 244 children were admitted to the pediatric ward of Nippon Kokan Hospital: 53 (21.7%) were hospitalized with influenza virus infection, 22 (9.0%) with rotavirus gastroenteritis, and 17 (7.0%) with respiratory syncytial virus infection. Among those with influenza, 24 had type A and 29 had type B. Most were young healthy children without underlying illnesses (mean age, 4.8 +/- 3.4 years). The impact of the influenza epidemic on pediatric hospitalization is probably much greater than generally thought when a severe epidemic occurs.

Increased expression in vivo and in vitro of foreign genes directed by A-type inclusion body hybrid promoters in recombinant vaccinia viruses

We constructed A-type inclusion body (ATI) hybrid promoters, that is, late ATI promoters followed by tandemly repeated early regions of the promoter for the 7.5-kDa protein (the 7.5-kDa promoter). The repetition of the whole early promoter sequence of the 7.5-kDa gene, including the upstream consensus sequence and initiation region, efficiently increased the early expression of the bacterial chloramphenicol acetyltransferase gene in recombinant vaccinia virus. Recombinant vaccinia virus could express influenza virus hemagglutinin via the hybrid promoter more efficiently, induced higher levels of neutralizing antibody and cytotoxic T lymphocytes, and consequently protected mice more efficiently against challenge with influenza virus than did recombinant vaccinia virus containing the widely used 7.5-kDa promoter.

The first isolation of swine H1N1 influenza viruses from pigs in Thailand

Two influenza A viruses were isolated from pigs in Thailand in January 1988 during the early febrile stage of an influenza-like illness. The isolates contained hemagglutinin and neuraminidase antigens related to those of swine H1N1 influenza virus. This result based on the virus isolation is compatible with the epizootiological evidence that, unlike the human influenza with peak activity in summer (May-July), swine influenza virus is prevalent in the winter season (November-January) in Thailand. The proportion of sera with hemagglutination-inhibiting antibody was higher to A/NJ/8/76 than to A/sw/Iowa/15/30. Likewise, hemagglutination-inhibition tests with monoclonal antibodies indicated that hemagglutinin antigen of the isolates was very similar to that of A/NJ/8/76 virus. In agreement with the serological survey and antigenic characteristic, genetic relatedness between the isolates from Thailand and A/NJ/8/76 virus was also demonstrated by the oligonucleotide mapping of RNA, suggesting that they may be of the same origin.

Homotypic and heterotypic protection against influenza virus infection in mice by recombinant vaccinia virus expressing the haemagglutinin or nucleoprotein of influenza virus

Recombinant vaccinia virus expressing the influenza virus haemagglutinin (HA) or nucleoprotein (NP) genes from A/SW/Hong Kong/1/74 (H1N1) under the control of a hybrid promoter containing the P7.5 early promoter element and promoter of the gene encoding the major protein of cowpox virus A type inclusion body was constructed to investigate protective immunity against homologous and heterologous viruses in mice. These recombinant vaccinia viruses produced authentic influenza virus HA and NP in infected cells. The recombinant vaccinia virus-influenza virus HA conferred efficient subtype-specific protection although mice challenged with heterologous influenza viruses underwent initial infection. By contrast, immunization with the recombinant vaccinia-influenza virus NP limited virus multiplication in the lungs against challenge infection with all H1N1 and H3N2 influenza viruses examined, although less efficiently. These results will prompt the re-examination of the possibility of using the recombinant vaccinia virus-influenza virus NP as a cross-protective vaccine.

Evolutionary pathways of N2 neuraminidases of swine and human influenza A viruses: origin of the neuraminidase genes of two reassortants (H1N2) isolated from pigs

The complete nucleotide sequences of the neuraminidase (NA) genes of two reassortant (H1N2) and two H3N2 influenza A viruses isolated from pigs were determined and phylogenetic relationships between these and previously reported N2 NA genes were investigated. On the basis of pairwise nucleotide sequence identity, the NA genes of two reassortants, A/sw/Kanagawa/2/78 and A/sw/Ehime/1/80, were most closely related to those of human influenza A virus strains isolated in 1972 and the earliest available swine H3N2 influenza A viruses, respectively. Phylogenetic trees showed that the NA genes can be segregated into three groups, including lineages for (i) swine strains, (ii) the earliest human strain and (iii) recent human strains. The evolutionary tree for the 11 nucleotide and amino acid sequences suggested that the NAs of A/sw/HK/4/76 and A/sw/Kanagawa/2/78 belong to the lineage for recent human viruses. In contrast, the NA genes of the A/sw/HK/3/76 and H1N2 reassortant A/sw/Ehime/1/80 viruses were found to be of a swine lineage. The swine virus NA genes were further characterized by the cocirculation of two distinct lineages. Although the rates of synonymous (silent) substitutions for the swine and human viruses were nearly identical (0.00946 to 0.00884 per site per year), the rate of non-synonymous (amino acid changing) substitutions for swine virus NA genes was about 60% of that for the human virus.

Molecular evolution of hemagglutinin genes of H1N1 swine and human influenza A viruses

The hemagglutinin (HA) genes of influenza type A (H1N1) viruses isolated from swine were cloned into plasmid vectors and their nucleotide sequences were determined. A phylogenetic tree for the HA genes of swine and human influenza viruses was constructed by the neighbor-joining method. It showed that the divergence between swine and human HA genes might have occurred around 1905. The estimated rates of synonymous (silent) substitutions for swine and human influenza viruses were almost the same. For both viruses, the rate of synonymous substitution was much higher than that of nonsynonymous (amino acid altering) substitution. It is the case even for only the antigenic sites of the HA. This feature is consistent with the neutral theory of molecular evolution. The rate of nonsynonymous substitution for human influenza viruses was three times the rate for swine influenza viruses. In particular, nonsynonymous substitutions at antigenic sites occurred less frequently in swine than in humans. The difference in the rate of nonsynonymous substitution between swine and human influenza viruses can be explained by the different degrees of functional constraint operating on the amino acid sequence of the HA in both hosts.

Characterization of antibody and cytotoxic T lymphocyte responses to human influenza virus H3 haemagglutinin expressed from the haemagglutinin locus of vaccinia virus

Antibody and cytotoxic T lymphocyte (CTL) responses to the haemagglutinin (HA) of human H3N2 influenza virus were analysed, using recombinant vaccinia viruses containing the influenza HA gene inserted into the HA gene locus of vaccinia virus. The recombinant vaccinia viruses elicited a high haemagglutination inhibiting (HI) antibody response to the homologous influenza virus in mice. In addition, HI antibody generated by the recombinant vaccinia virus reacted with antigenic variants of human H3N2 influenza virus in a manner similar to that elicited by the HA vaccine. Mice with a high response to influenza virus HA vaccine were highly responsive to the HA expressed from the recombinant vaccinia virus, as measured by HI antibody production. The immunogenicity of the influenza virus HA expressed by the recombinant seems to be attributable to the intrinsic immunogenicity of the HA molecule. The recombinants primed mice for an influenza virus H3-specific CTL response and primed CTLs recognized the target cells in a subtype-specific manner. The results indicate that a recombinant vaccinia virus derived by the insertion of a foreign gene into its HA gene locus is a potent live vaccine not only for eliciting a high antibody response but also for priming a specific CTL response.

Development of a new type of influenza subunit vaccine made by muramyldipeptide-liposome: enhancement of humoral and cellular immune responses

The muramyldipeptide (MDP), [6-O-(2-tetradecyl-hexa-decanoyl)-N-acetylmuramyl-L-isoglutamine] can be incorporated into liposomes with haemagglutinin and neuraminidase subunits were attached to the inner and outer surfaces of lamellar structures of the liposomes, probably through their hydrophobic ends. The addition of cholesterol resulted in much more stable liposomes, which were similar in size and shape to native influenza virus particles. These liposomes enhanced the immunogenicity of haemagglutinin in mice, such that the levels of antibody induced were about 16-fold higher than those of subunit haemagglutinin vaccine alone. Results of proliferation tests with spleen cells from mice and guinea-pigs were consistent with the immunopotentiation of haemagglutinin by liposomes. In addition, the higher antibody levels produced in mice, immunized with the haemagglutinin and MDP-containing liposomes (MDP-virosomes), were maintained for at least 6 months. Enhancement of the cellular immune response, measured by delayed type hypersensitivity reactions, was also observed in the guinea-pigs immunized with MDP-virosome vaccine. Preliminary tests with splenocytes from mice immunized with different vaccines also indicated that the MDP-virosome vaccine induced cytotoxic T-cell activity in these mice. This study revealed that the formation of liposomes with muramyldipeptide enhanced the level and persistence of circulating antibody, and enhanced cellular immunity in guinea-pigs and mice.

Biological and immunological characterization of influenza virus haemagglutinin expressed from the haemagglutinin locus of vaccinia virus

Plasmid vectors were constructed to facilitate the insertion and expression of a foreign gene in the haemagglutinin (HA) gene locus of vaccinia virus. Five unique cloning sites adjacent to the P7.5 promoter of vaccinia virus permit the rapid insertion of a foreign sequence coding for a protein into these plasmids. This vector system provides a simple procedure to select recombinant viruses because they can be readily identified on the basis of their HA-defective phenotype. Recombinant vaccinia viruses expressing influenza virus HA were constructed to characterize the possible use of this system. The recombinant viruses did express the influenza HA through the authentic pathway of biosynthesis. In addition to having immunological characteristics similar to the authentic influenza HA, the expressed HA was found to possess haemagglutinating, haemadsorption and acid-inducible fusion activities. These findings demonstrate the usefulness of this eukaryotic vector system.

Evolutionary pattern of the hemagglutinin gene of influenza B viruses isolated in Japan: cocirculating lineages in the same epidemic season

The unexpectedly low efficacy of influenza vaccine during school outbreaks of influenza B virus in the spring of 1987 in Japan was probably attributable to a poor antibody response of vaccinees to the epidemic viruses. An antigenic analysis of the causative B viruses isolated in 1987 and 1988 showed much variation in hemagglutination inhibition patterns. The nucleotide sequences that code for the HA1 domain of B/Fukuoka/c-27/81, B/Ibaraki/2/85, B/Nagasaki/1/87, and B/Yamagata/16/88 viruses were determined and compared with those of the previously reported hemagglutinin genes. The nucleotide sequences of the hemagglutinin gene of a new variant, B/Yamagata/16/88, had only 93.4% homology with those of two other viruses from the same epidemic. An analysis of nucleotide and amino acid substitutions of the hemagglutinin genes of influenza B viruses revealed that new and some old variants could cocirculate in the same epidemic. A phylogenetic tree constructed by the neighbor-joining method allowed estimation of an evolutionary rate of 2.3 x 10(-3) synonymous (silent) substitutions per nucleotide site per year in the hemagglutinin gene.

Cocirculation of two distinct evolutionary lineages of influenza type B virus since 1983

During 1988-1989 two highly distinct antigenic variants of influenza type B were recognized in hemagglutination-inhibition tests with postinfection ferret serum. These viruses were antigenically related to either B/Victoria/2/87, the most recent reference strain, or B/Yamagata/16/88, a variant that was isolated in Japan in May 1988. All influenza B viruses isolated in the United States during an epidemic in the winter of 1988-1989 were antigenically related to B/Victoria/2/87. However, in several countries in Asia, both B/Victoria/2/87-like viruses and B/Yamagata/16/88-like viruses were isolated. Sequence analysis of the hemagglutinin (HA) genes of several influenza B isolates from 1987 to 1988 indicated that the HA1 domains of the B/Yamagata/16/88-like viruses and B/VI/87-like viruses isolated in 1988 differed by 27 amino acids. Evolutionary relationships based on this sequence data indicated that the B/Yamagata/16/88-like viruses were more closely related to epidemic viruses from 1983 (B/USSR/100/83-like viruses) than to more recent reference strains such as B/Victoria/2/87. All other Asian strains, as well as selected isolates from the United States in 1988, were confirmed by sequence analysis as being genetically related to B/Victoria/2/87. These data provide clear evidence that two parallel evolutionary pathways of influenza type B have existed since at least 1983 and that viruses from each of the separate lineages were isolated from cases of influenza B in 1988. This finding is similar to earlier observations for type A H1N1 and H3N2 influenza viruses.

Difference in growth behavior of human, swine, equine, and avian influenza viruses at a high temperature

Growth characteristics of a wide range of influenza A viruses from different mammals and bird species were examined in an established line of canine kidney (MDCK) cells at an ordinary (37 degrees C) and a high temperature (42 degrees C). Although all viruses employed in the present study possessed a capability of replicating at 37 degrees C, virus growth at 42 degrees C showed considerable variation and reflected differences in the natural hosts of the isolates. All reference strains and isolates from bird species grew well in the MDCK cells maintained at 42 degrees C, but human viruses did not, showing an asymmetrical growth behavior. In contrast to this, growth of swine and equine viruses showed growth characteristics intermediate between human and avian viruses. Of the two swine viruses examined, replication of one strain occurred equally well at both temperatures and another failed to grow at 42 degrees C. Similarly, two of the three equine viruses tested belonging to H3N8 antigenic subtypes grew at 42 degrees C. However, the results obtained from comparison of plaque sizes and growth curves indicated that the replication of the above swine and equine viruses was restricted under a stringent temperature when compared to avian viruses. The detailed analysis of cloned viruses revealed that some of the swine and equine viruses contained two variants which are readily distinguished by growth behavior at 42 degrees C. Genome analysis of parental and virus clones by oligonucleotide mapping and migration profiles of RNA segments did not detect any differences among the above variants exhibiting the asymmetrical growth characteristics at 42 degrees C.

Antigenic variation of Newcastle disease viruses isolated from wild ducks in Japan

Nineteen strains of Newcastle disease virus (NDV) isolated from wild ducks in Japan were placed into 4 distinct antigenic groups on the basis of their reactivities to 8 monoclonal antibodies against the HN molecule of NDV in hemagglutination inhibition tests. The NDV strains of duck origin were antigenically distinct from NDV-B1 and NDV-Miyadera originated from chickens, and varied in their virulence to chicken embryos. No apparent correlation was found between the antigenicity of the HN molecule and virulence.

Serological and pathological studies of Newcastle disease viruses isolated from caged birds from Southeast Asia

Eleven isolates of Newcastle disease virus (NDV), from caged birds imported from or captured in Southeast Asia in 1979-80, were antigenically divided into five distinct groups. Most of them were distinguishable from more classical NDVs (vaccine B1 strain and Miyadera strain) on the basis of their reactivity to eight monoclonal antibodies against the HN molecule of NDV in hemagglutination-inhibition tests. However, when three representative isolates were evaluated for their biological properties and pathogenicity against 1-day-old chickens, all three were found to be velogenic types that could induce serious symptoms of Newcastle disease and which eventually killed all of the chickens, regardless of the route of infection. There was not any significant correlation between their reactivity patterns with the monoclonal antibodies and their virulence.

Human influenza A virus hemagglutinin distinguishes sialyloligosaccharides in membrane-associated gangliosides as its receptor which mediates the adsorption and fusion processes of virus infection. Specificity for oligosaccharides and sialic acids and the sequence to which sialic acid is attached

Human influenza A virus isolates bearing antigenically different H1 (A/PR/8/34), H2 (A/Japan/305/57), and H3 (A/Aichi/2/68, A/X-31) hemagglutinin serotypes caused extensive hemagglutination, low pH fusion, and hemolysis of asialoerythrocytes reconstituted with gangliosides. Sialylparaglobosides (IV3NeuAc-nLc4Cer, IV6NeuAc-nLc4Cer), I-active and i-active (VI3NeuAc-nLc6Cer) gangliosides, and GM3-NeuAc commonly exhibited significant specific receptor activity toward the viruses. A/PR/8/34 recognized IV3NeuAc-nLc4Cer containing the NeuAc alpha 2-3Gal sequence preferentially over IV6NeuAc-nLc4Cer containing NeuAc alpha 2-6Gal, whereas the other two recognized the NeuAc alpha 2-6Gal sequence preferentially over NeuAc alpha 2-3Gal. Responsiveness of erythrocytes labeled with gangliosides containing NeuGc to the viruses used was considerably lower than that of erythrocytes labeled with gangliosides containing NeuAc. The activities of GM1a, GM2, and GD1b bearing NeuAc on inner galactose of the ganglio series core were also very low. These results indicate that sialyloligosaccharides of IV3NeuAc-nLc4Cer, IV6NeuAc-nLc4Cer, I-active ganglioside, and VI3NeuAc-nLc6Cer in addition to GM3-NeuAc and GM1b-NeuAc (Suzuki, Y., Matsunaga, M., and Matsumoto, M. (1985), J. Biol. Chem. 260, 1362-1365; Suzuki, Y., Matsunaga, M., Nagao, Y., Taki, T., Hirabayashi, Y., and Matsumoto, M. (1985) Vaccine 3, 201-203) are functional receptor determinants toward hemagglutinin of human influenza A viruses, and the viruses differentiate microdomains of the gangliosides, such as the sialic acid species (NeuAc, NeuGc) and the sequence of sialic acid linkages (NeuAc alpha 2-3Gal, NeuAc alpha 2-6Gal).