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At least 19 recordsLinked to original sources

PubMed1977

Immunologic recognition of influenza virus-infected cells. II. Expression of influenza A matrix protein on the infected cell surface and its role in recognition by cross-reactive cytotoxic T cells.

Two distinct subpopulations of cytotoxic T cells are generated in the primary or secondary response of mice to type A influenza viruses. One subpopulation is specific for the immunizing virus strain. The other subpopulation shows a high degree of cross-reactivity for heterologous type A virus of a different subtype. This report examines the possibility that distinct influenza virus antigens, expressed on the surface of the infected cell, are recognized by the different subpopulations of influenza-specific cytotoxic T cells. Data are presented which demonstrate that influenza A matrix protein, an internal virion antigen, is detectable on the surface of target cells infected with influenza A viruses of different subtypes. Since this viral antigen is type specific, i.e., serologically cross-reactive among all type A influenza viruses, it could serve as the target for cross-reactive cytotoxic T cells. To further examine the specificity of the two cytotoxic T-cell subpopulations, experiments were carried out by using the inhibitor of glycoprotein synthesis - 2-Deoxy-D-Glucose 2-DG. These experiments examine first the effect of 2-DG on the expression of influenza matrix protein and viral glycoprotein on the infected cell surface and second, the susceptibility of 2-DG-treated target cells to lysis by cytotoxic T cells. 2-DG inhibits the expression of the viral hemagglutinin glycoprotein on the cell surface but does not inhibit the expression of the nonglycosylated matrix protein. Furthermore, inhibition of glycoprotein synthesis in infected target cells abrogates the reactivity of infected target cells to lysis by virus strain-specific but not cross- reactive cytotoxic T cells. These findings suggest that the influenza glycoproteins (hemagglutinin and/or neuraminidase) and the nonglycosylated matrix protein are the targets for the virus strain- specific and cross-reactive cytotoxic T cells, respectively. These results are discussed in the light of available information on influenza virus structure and the biology of influenza infection and in terms of current models for cytotoxic T-cell recognition of virus-infected cells.

Antibodies, Viral↗

PubMed2026

Clinical and genomic characterization of Influenza A co-infection with SARS-CoV-2 and Influenza B: a respiratory surveillance study in Assam, India.

Influenza and SARS-CoV-2 are the primary contributors to seasonal respiratory infections and frequently co-circulate, creating significant health challenges. The present respiratory surveillance study was conducted in Dibrugarh, Assam, India from January 2025 to August 2025 to investigate the genomic characteristics of circulating viruses and identify potential co-infections. Overall, 4,948 respiratory samples were screened using multiplex real-time PCR, followed by subtyping of Influenza A and Influenza B. Next-generation sequencing (NGS) was performed in selected positives of SARS-CoV-2 and Influenza A. Genomic analysis included mutational profiling, phylogenetic analysis and N-glycosylation site prediction using bioinformatics tools. Two co-infection cases were detected: one involving Influenza A (H3N2) with SARS-CoV-2 (Omicron XFG lineage) and another involving Influenza A (H3N2) with Influenza B (Victoria lineage). Both patients experienced mild illness without hospitalisation. NGS revealed that the Influenza A (H3N2) viruses belonged to clade 3C.2a1b.2a.2a.3a.1 while SARS-CoV-2 sequence was classified under the Omicron XFG lineage. Mutational analysis of the HA gene showed several amino acid differences compared to the reference vaccine strain A/Darwin/6/2021. N-glycosylation analysis predicted conserved sites at positions 79, 181, 262, and 301 in all strains along with an additional predicted site at position 110 in both co-infection cases. Although the co-infection cases presented with mild clinical manifestations, the observed genomic variations indicate a potential role of co-infecting viruses in shaping viral evolution. Given the limited genomic data available from Northeast India, the study underscores the need for sustained large scale follow up and genomic surveillance to monitor emerging mutations and target future vaccine strategies.

Humans↗

PubMed1977

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.

Antibodies, Viral↗

PubMed1979

Laboratory-based surveillance of influenza virus in the United States during the winter of 1977-1978. I. Periods of prevalence of H1N1 and H3N2 influenza A strains, their relative rates of isolation in different age groups, and detection of antigenic variants.

Influenza A (H3N2) viruses were isolated from outbreaks and epidemics of disease during the period December 1977 to March 1978. For the last two months of this period, H1N1 strains of influenza A were also responsible for epidemics. In some regions (e.g., Hawaii) co-circulation of H1N1 AND H3N2 strains occurred, whereas in other regions (e.g., Wisconsin) isolation of H3N2 strains had almost ceased prior to isolation of H1N1 strains. Few influenza B isolates were reported. Analysis of the ages of patients from whom specimens were submitted for influenza virus isolation confirmed that, whereas H3N2 strains were isolated from persons of all ages, greater than 97 per cent of H1N1 isolates in six states analyzed were recovered from patients less than 26 years old, although specimens were tested from older persons who were ill during the period of prevalence of H1N1 influenza. The majority of H3N2 isolates tested by hemagglutinin-inhibition reaction were similar to A/Texas/1/77, and the majority of H1N1 isolates were similar to A/USSR/90/77. Antigenic analysis of isolates, however, identified a small number of variants of H3N2 and H1N1 strains.

Adolescent↗

PubMed1978

The recovery of mice from influenza A virus infection: adoptive transfer of immunity with influenza virus-specific cytotoxic T lymphocytes recognizing a common virion antigen.

Mice inoculated intranasally with infectious influenza virus of a given A strain were adoptively transferred 24 h later with preparations of secondary influenza virus-immune T cells generated either in vitro or entirely in vivo. The immune cells were raised during infection with homologous or heterologous A strain influenza viruses or with a type B virus. The greatest antiviral effect, measured by reduction in lung virus level of recipient mice, occurred if homologous viruses were used. Sharing of haemagglutinin specificity was shown to be important, but significant antiviral activity was still expressed if neither haemagglutinin nor neuraminidase antigenic specificities were shared. The antiviral effect was type-specific. Adoptive transfer of type A influenza immune T cells did not express antiviral activity against type B virus, and vice versa. On the basis of earlier work, the effector population in the transferred cells was cytotoxic T cells (Tc). Intranasal reinfection of mice with a heterologous type A virus sharing neither haemagglutinin nor neuraminidase antigenic specificity with the first infecting virus induced enhanced and earlier production of cross-reactive Tc against type A influenza viruses. This was paralleled by significantly lower virus levels in the lungs. The results of this work demonstrate heterotypic cell-mediated immunity in influenza virus infection in mice.

Animals↗

PubMed1977

Pharyngeal colonization with Haemophilus influenzae type b: a longitudinal study of families with a child with meningitis or epiglottitis due to H. influenzae type b.

A longitudinal study of pharyngeal colonization with Haemophilus influenzae type b included 264 members of families that had a child with meningitis or epiglottitis due to this organism. It was found that (1) 52 of 67 such families contained at least one carrier of H. influenzae type b, who was usually a sibling; (2) H. influenzae type b spread slowly in 39 families colonized continuously during a six-month period, with only eight of 19 uncolonized siblings acquiring the organism during that time; (3) 18 of 30 initially colonized families contained one or more carriers after 12 months, including 30% of initially colonized siblings; (4) the highest carrier rate of H. influenzae type b occurred in recovered patients, 80% of whom were colonized after hospital discharge; (5) titers of antibody in serum were higher in colonized than in uncolonized individuals (P less than 0.001); (6) levels of antibody in colonized children were lower in those younger than two years than in older children (P less than 0.001); and (7) prolonged or heavy colonization with H. influenzae type b was not associated with unusually high titers of antibody.

Age Factors↗

PubMed1978

Novel influenza A viruses isolated from Canadian feral ducks: including strains antigenically related to swine influenza (Hsw1N1) viruses.

Twelve influenza A viruses, antigenically related to the Ho, H1 and Hsw1 subtypes, were isolated from cloacal samples of feral ducks in Canada. Antigenic comparisons showed that these viruses were most closely related to the recent HSW1N1 isolates from man and pigs, whereas in vivo pathogenicity tests revealed differences between the Hsw1N1 viruses from the ducks and those from humans and pigs. Antigenic characterization of 94 additional influenza A viruses from the ducks showed four haemagglutinin subtypes (Hav1, Hav4, Hav5 and Hav7), an unclassified haemagglutinin, and six neuraminidase subtypes (N1, N2, Neq2, Nav1, Nav2 and Nav5) in various combinations, some of which are novel and have not previously been reported. Three of these duck influenza viruses possessed a haemagglutinin antigenically related to that of classical fowl plaque virus. A much higher percentage of virus isolations were from juvenile ducks (18.5%) than from adults (5%). All of the ducks, from which viruses were isolated, appeared healthy at the time of sampling. Serological studies on a limited number of humans and domestic birds living in close proximity to the Canadian ducks revealed no evidence of interspecies transmission. Our findings suggest that these birds serve as a substantial reservoir of antigenically diverse influenza viruses, including isolates antigenically related to the current human and animal influenza viruses. This reservoir in nature may be perpetuated by a cycle involving annual infection of juvenile birds followed by transmission to the remaining susceptible birds until the next congregation during the breeding season.

Animals↗

PubMed1977

Influenza surveillance 1972-75. By the Public Health Laboratory Service Standing Advisory Committee on Influenza.

The surveillance programme described in an earlier report was used to monitor outbreaks of influenza in three successive winters. Influenza virus A was active in all of them, but the only major outbreak of influenza B was in 1973--4. The highest incidence of influenza A was in the 0--4 age group in all three winters, but schoolchildren bore the brunt of infections by influenza virus B.

Adolescent↗

PubMed1979

[Experimental pneumonia caused by an association of H. influenzae and the influenza virus].

Experiments in 400 non-inbred white mice indicated that the association of influenza virus A2 Hong Kong with H. influenzae enhanced the pathogenic action of the causative agents and led to the unfavorable clinical outcome only in those cases when these agents penetrated the body simultaneously, or when viral infection preceded bacterial infection. In those cases when influenza infection appeared in the presence of bacterial infection, the pathological process developed as a monoviral disease. The morphological changes in the lungs of the mice infected with H. influenzae corresponded to lesions caused by influenza virus and were manifested by pronounced hemodynamic disturbances.

Animals↗

PubMed1977

Antibody to influenza virus matrix protein detects a common antigen on the surface of cells infected with type A influenza viruses.

Antisera to the type-specific internal influenza virus matrix (M) protein of a type A influenza virus were produced in goats. In the presence of complement, anti-M serum was cytotoxic for target cells which were infected with a variety of serologically distinct type A influenza viruses, but did not react with type B influenza virus-infected cells. Absorption experiments indicated that anti-M serum detected a common antigen(s) on the surface of type A-infected cells. This serological cross-reactivity parallels the cross-reactivity observed for the cytotoxic T-cell response to type A viruses.

Antibodies, Viral↗

PubMed1976

Swine influenza virus and the recycling of influenza-A viruses in man.

Sera collected in 1967 and 1972 from people in the 0-100 age-group showed haemagglutination-inhibition (H.I.) antibody to swine virus A/Iowa/15/30 (Hsw1N1) in greatest number and with highest titre in people born before 1918. A slight decrease was observed from 1967 to 1972 in the number of sera with antibody to swine virus and in the height of the titres. The recently isolated A/New Jersey/10/76 (Hsw1N1) virus showed a result comparable to that of the Swine/1930 virus in sera of 1972. On the analogy of the findings in 1968, when the Hong Kong virus became epidemic in human populations and antibody to this virus was found in sera of people over 70 years, the suggestion is made that the recurrence of swine virus as an epidemic agent of human influenza may be expected around 1986. Fourfold or greater increase of antibody to Swine/1930 virus was observed in about 4--5% of people infected by or immunised with H3N2 viruses. This response occurred in people who had been in touch with the epidemic influenza-A viruses Hsw1N1, H0N1, and H1N1 during the swine era of 1918 to 1956. Following immunisation with H3N2 viruses of persons showing no response to H3N2 viruses in their serum 5% did show a fourfold or greater heterotypic H.I. antibody rise to swine virus. This finding is of consequence for the diagnostic serology of influenza.

Adolescent↗

PubMed1979

Assessment of inactivated influenza-A vaccine after three outbreaks of influenza A at Christ's Hospital.

The boys of Christ's Hospital experienced outbreaks of influenza A in 1972 (A/England/42/72), in 1974 (A/Port Chalmers), and in 1976 (A/Victoria). In each outbreak, the protective effect of inactivated influenza-A vaccine was limited to those boys, not already immune, who were vaccinated for the first time with the most up-to-date strain. Revaccination with the same strain did not increase the degree of protection, and revaccination with a later strain did not afford protection against subsequent challenge. The cummulative attack-rate in the three outbreaks was similar in all groups irrespective of vaccination history. These observations suggest that annual revaccination with inactivated influenza-A vaccine confers no long-term advantage.

Adolescent↗

PubMed1979

Live Victoria/75-ts-1[E] influenza A virus vaccines in adult volunteers: role of hemagglutinin immunity in protection against illness and infection caused by influenza A virus.

To explore the relationship between neuraminidase immunity and the degree of attenuatíon of live influenza A virus vaccines, a comparative evaluation of three Victoria/75-ts-1[E] (Vic/75-ts-1[E]) recombinant viruses in serum hemagglutination-inhibiting-negative (titer, </=1:8) adult volunteers was performed. These three ts-1[E] viruses had a similar restriction of replication at 38 degrees C in vitro, and each possessed the two attenuating genes of the ts-1[E] donor strain (13). However, Vic/75-ts-1[E] recombinants 81 and 113 possessed both Vic/75 hemagglutinin (H3(75)) and Vic/75 neuraminidase (N2(75)), whereas Vic/75-ts-1[E] recombinant 67 had Vic/75 hemagglutinin but the N2(65) neuraminidase. Vic/75-ts-1[E] recombinant 67 was significantly more attenuated than Vic/75-ts-1[E] recombinants 81 and 113 in that fewer local and systemic signs and symptoms of illness were observed in those volunteers who received clone 67. These findings were consistent with our previous observations which suggested that the following two factors contribute to the attenuation of ts-1[E] vaccine strains in adults: (i) the attenuating effect of the two ts-1[E] genes and (ii) the neuraminidase immunity of the host. Vic/75-ts-1[E] recombinant clone 67 vaccinees developed an immunological response to the H3(75) hemagglutinin in the absence of a response to the N2(75) neuraminidase. To assess the role that anti-hemagglutinin immunity induced by an attenuated live virus vaccine plays in resistance to influenza A virus, vaccinees who received recombinant 67 were challenged with Vic/75 wild-type virus, and their responses were compared with those of Vic/75-ts-1[E] vaccinees who received recombinant 81 or 113. Each of the three groups of ts-1[E] vaccinees was significantly protected against illness induced by wild-type virus infection, although resistance was not complete. However, the clone 67 vaccinees were protected less against infection. The infection-permissive resistance induced by clone 67 resembled that previously described for inactivated neuraminidase-specific vaccines. These results suggested that a ts-1[E] recombinant that possessed the hemagglutinin of a new pandemic variant, the neuraminidase of the preceding subtype, and the two ts-1[E] ts genes would be satisfactorily attenuated for children and adults with neuraminidase immunity and could induce resistance to illness caused by the new pandemic wild-type influenza A virus.

Adolescent↗

PubMed1977

The use of transportable single-radial-diffusion immunoplates in seroepidemiological studies of influenza in the Gambia. The occurrence and persistence of antibody to influenza A/Hong Kong/68 (H3N2) virus in selected inhabitants of two rural villages.

Seroepidemiological studies of influenza in the Gambia were made using transportable single-radial-diffusion immunoplates containing A/Hong Kong/68 (H3N2) virus as antigen. The frequency and durability of antibody so detected in selected residents of two Gambian villages (Manduar and Kafuta) are described. Transportable immunoplates were found to be an effective method for the serological surveillance of influenza and to be applicable in studies in remote areas where laboratory facilities may not be available. Results indicated that infection with influenza was widespread in Manduar residents on several occasions between 1968 and 1974 and that reinfection with A/Hong Kong/68 virus or its antigenic variants occurred frequently. Serum levels of antibodies to the haemagglutinin and neuraminidase antigens of the A/Hong Kong/68 virus often persisted for only a short time (mean half-life about 28 days), particularly after first infections. Antibody persistence increased following repeated reinfection. No precise explanation can be offered at present for the relatively short persistence of antibodies in Gambians. Possible reasons include genetic and environmental factors, depressed immunological reactivity associated with concurrent infection (notably parasitic diseases), and unusually high rates of synthesis and catabolism of immunoglobulins. The value of transportable immunoplates for serological surveys and for accurate assessment of antibody persistence is discussed.

Adolescent↗

PubMedDate not supplied

Neutralizing influenza antibodies, IgA and total protein in the nasopharyngeal secretions of subjects vaccinated by nasal route with the inactivated influenza vaccine prepared in the "Stefan S. Nicolau" Institute of Virology.

Intranasal administration of two doses of the inactivated influenza vaccine prepared in the "Stefan S. Nicolau" Institute of Virology was followed by rises in the level of neutralizing secretory influenza antibodies in 82% of the cases. The concomitant study of secretory antibody, IgA and total protein levels, as well as of the serum HAI influenza antibodies demonstrated that their evolution was parallel only in 23% of the vaccinees. The percentage of secretory antibody conversion was similar to the rate of protection conferred by the vaccine.

Administration, Intranasal↗

PubMedDate not supplied

[Experimental model of associated influenza-para-influenza infection].

An experimental model of associated influenza-parainfluenza infection has been developed. Simultaneous inoculation of mice with influenza A2/21/65 and parainfluenza type 3 or inoculation with these viruses at an interval of 24 hours was shown to produce a considerably more severe disease as manifested by the development of severe confluent pneumonias involving both lungs and death of the inoculated animals. The animals with the associated infection showed no significant difference in antibody titers or the intensity of immunity as compared with control groups (influenza or parainfluenza monoinfection). The development of the mixed infection was accompanied by the inhibition of neutrophilic and macrophage phagocytosis and inhibition of interferon production.

Animals↗

PubMed1978

T lymphocytes as an indicator in influenza vaccination, influenza and acute respiratory diseases.

Significant differences in T-lymphocyte counts in the peripheral blood of normal subject and volunteers vaccinated with live and inactivated influenza vaccines as well as patients with influenza and viral acute respiratory diseases (ARD) were demonstrated. A laboratory test using T lymphocytes was proposed for the evaluation of the safety of live influenza vaccine.

Adenoviridae Infections↗

PubMed1979

Natural history of influenza in swine in Hawaii: swine influenza virus (Hsw1N1) in herds not infected with lungworms.

To obtain more information on mechanisms by which influenza virus is perpetuated in swine, retrospective and prospective seroepizootiologic observations were made in swine herds in Hawaii, beginning in 1974. An epizootic of swine influenza (Hsw1N1) virus was observed in November and December 1976, involving 31 of 41 herds. Features of the epizootic included (1) infection of all herds within one geographic location, during a short period; (2) no obvious introduction of virus from the outside in most herds; (3) epizootics mainly in herds with serologic history of infection; (4) no evidence that lungworms were involved; and (5) little clinical disease associated with infection. There was evidence of viral activity in some herds before the epizootic period and afterward in two of three herds monitored. Evidence of viral transmission by feral animals was not obtained. Data indicated that swine influenza virus persists through latently or chronically infected swine, with epizootics occurring when herd immunity reaches a critically low degree.

Animals↗