Number Of Influenza Research Articles

Monitoring of Influenza Viruses in the Aftermath of the Great East Japan Earthquake

Influenza has a significant impact on public health when a natural disaster occurs during the influenza season. However, the epidemiological characteristics of influenza following natural disasters have not been well documented due to the difficulty of implementing laboratory-based influenza surveillance in such situations. The Great East Japan Earthquake occurred on March 11, 2011, when influenza was already circulating. Since routine influenza surveillance was not performed in Miyagi Prefecture, we initiated an ad hoc laboratory-based monitoring system immediately after the earthquake. From March 15 to May 19, we tested 277 samples for influenza virus collected around Sendai City and from evacuation centers in Miyagi Prefecture. Influenza A (H3N2) was detected in 112 cases, influenza A (H1N1) 2009 in one case, and influenza B in 92 cases. The H3N2 virus was dominant until the 14th week. However, a sudden increase in the number of influenza B cases occurred after schools were reopened. According to phylogenetic analysis, a major clade switch of the H3N2 virus took place after the earthquake. The Yamagata lineage of influenza B was detected in one patient from western Japan, indicating the importing of viruses into the affected area.

Confirmation diagnosis of influenza A(H1N1)2009 by Belgian sentinel laboratories during the epidemic phase

From 13 July onwards, the Interministerial Influenza Coordination Committee announced the switch from the containment phase to a mitigation phase due to the increased number of Influenza A(H1N1)2009 cases [1,2]. This modified approach means that it is no longer necessary to conduct a virological examination for every suspicious case and that the diagnosis relied on clinical criteria again. It also required the initiation of several surveillance systems allowing the follow-up of the infection. However, for some patients a virological confirmation was still needed due to their clinical evolution or clinical history. Because of the high amount of these requests, it was proposed to decentralise the diagnostic capacity from the Belgian National Influenza Centre (NIC) to a network of 'partner' laboratories. Therefore, all sentinel laboratories were invited to implement the diagnostic tests, to participate in epidemiological surveillance in the frame of the sentinel laboratory network, to participate in virological surveillance by sending laboratory results or strains to be further subtyped at the NIC. A network of 15 laboratories that responded favourably was thus installed and used as an additional tool for the virological surveillance of the Influenza A(H1N1)2009, allowing the identification of circulating types and subtypes. Here we report on the data gathered by this network for the period from week 40 to week 53 of 2009.

A TLR3 ligand that exhibits potent inhibition of influenza virus replication and has strong adjuvant activity has the potential for dual applications in an influenza pandemic

The appearance and spread of the H5N1 highly pathogenic avian influenza (HPAI) raise concern of a possible pandemic. Current preventive measures include the development of a pre-pandemic influenza vaccine and stockpiling of neuraminidase inhibitors. However, their benefits can be significantly reduced by mutations in the hemagglutinin or neuraminidase resulting in antigenic changes and the appearance of drug-resistance, respectively. Drugs that target the innate immune system to achieve a ‘heightened antiviral’ state represent another class of antiviral agents that could contribute to the control and treatment of influenza infection. In this study, PIKA (a stabilized dsRNA) provides broad-spectrum prophylaxis against a number of influenza A viruses. In addition, when PIKA was admixed with influenza vaccine preparations, including a formalin-inactivated whole-virion H5 vaccine, significant adjuvanting effect leading to accelerated viral clearance was observed in a murine model. These biological effects appear to be mediated by the ability of PIKA to promote the maturation of dendritic cells, including up-regulation of co-stimulatory molecules, such as CD80 and CD86, and the induction of various cytokines and chemokines. Toll-like receptor 3 (TLR3) was shown to recognize PIKA in a concentration-dependent manner. The potency and versatility in its activities make PIKA an attractive candidate for use in an influenza pandemic.

A Mutation on Influenza C Virus M1 Protein Affects Virion Morphology by Altering the Membrane Affinity of the Protein

Reverse genetics has been documented for influenza A, B, and Thogoto viruses belonging to the family Orthomyxoviridae. We report here the reverse genetics of influenza C virus, another member of this family. The seven viral RNA (vRNA) segments of C/Ann Arbor/1/50 were expressed in 293T cells from cloned cDNAs, together with nine influenza C virus proteins. At 48 h posttransfection, the infectious titer of the culture supernatant was determined to be 2.51 x 10(3) 50% egg infectious doses/ml, which is lower than the number of influenza C virus-like particles (VLPs) (10(6)/ml) generated using the same system. By generating influenza C VLPs containing a given vRNA segment, we showed that each of the vRNA segments was similarly synthesized in the plasmid-transfected cells but that some segments were less efficiently incorporated into the VLPs. This finding leads us to speculate that the differences in incorporation efficiency into VLPs between segments might be a reason for the inefficient production of infectious viruses. Second, we generated a mutant recombinant virus, rMG96A, which possesses an Ala-->Thr mutation at residue 24 of the M1 protein, a substitution demonstrated to be involved in the morphology (filamentous or spherical) of the influenza C VLPs. As expected, rMG96A exhibited a spherical morphology, whereas recombinant wild-type of C/Ann Arbor/1/50, rWT, exhibited a mainly filamentous morphology. Membrane flotation analysis of the cells infected with rWT or rMG96A revealed a difference in the ratio of membrane-associated M1 proteins, suggesting that the affinity of M1 protein to the cell membrane is a determinant for virion morphology.

Influenza surveillance and antigenic and genetic characterization of predominant strains in Wuhan area in 2003

To study influenza epidemic and analyze antigenic and genetic characterization of the predominant strains in Wuhan area in 2003. Epidemiological data and specimens from influenza patients were collected from surveillance sites weekly. Viruses were isolated from the specimens. Three H3 isolates were chosen to do antigenic analysis by hemagglutination inhibition (HI) test and their HA1 region was sequenced. Totally 58 influenza viruses were isolated from 418 specimens, 57 of them were identified as H3 subtype and 1 of them was B subtype; both monthly positive rate and numbers of influenza like illness had two peaks of winter and summer, the highest peak appeared in July. The 3 new H3 isolates were antigenically different from vaccine strain A/Panama/2007/99, 14 amino acid changes have been found in HA1 domain of these 3 strains compared with A/Panama/2007/99, phylogenetic analysis also confirmed the difference in HA1 domain. Influenza epidemic had two peaks in Wuhan area in 2003. The activity of H3 virus was strengthened remarkably. And they are antigenically and genetically different from the vaccine strain.

Influenza Activity-- United States and Worldwide, April-October 2000

During October 1999-May 2000, influenza A(H3N2), A(H1N1), and B viruses were identified in the Northern Hemisphere. Influenza A(H3N2) predominated, but the number of influenza A(H1N1) viruses increased toward the end of the influenza season in the Northern Hemisphere. Since April, influenza A viruses have predominated in the Southern Hemisphere and tropical regions, but influenza B viruses also have been identified. This report summarizes influenza activity in the United States and worldwide from April 2000 through October 2000.

The Ability of Influenza C Virus to Generate Cord-like Structures Is Influenced by the Gene Coding for M Protein

We observed previously that cord-like structures which had lengths up to 500 μm or greater were protruding from the surface of HMV-II cells infected with influenza C/Yamagata/1/88 virus (Nishimura et al., 1990, Virology 179, 179-188). Comparison of the cord-forming ability among a number of influenza C isolates revealed that the C/Taylor/1233/47 strain was unique in lacking the ability. It was also found that the major structural proteins, hemagglutinin-esterase (HE), nucleoprotein (NP), and matrix (M), could each be distinguished between C/Yamagata/1/88 and C/Taylor/1233/47 viruses by SDS-polyacrylamide gel electrophoresis. To determine the genes involved in the cord formation, a series of reassortant viruses were prepared between C/Yamagata/1/88 and C/Taylor/1233/47, and parental derivation of genes coding for HE, NP, and M was determined by gel electrophoresis. All reassortants which derived M gene from C/Yamagata/1/88, irrespective of derivation of genes coding for HE and NP, had the ability to generate cords, whereas none of reassortants which derived M gene from C/Taylor/1233/47 were capable of producing cords. With respect to several representative reassortants, the origins of genes encoding the polymerase proteins (PB2, PB1, P3) and the nonstructural proteins (NS1, NS2) were determined by T1-oligonucleotide fingerprinting of the isolated RNA segments. The results suggested that none of genes coding for these proteins are exclusively associated with the cord formation. Thus, it is likely that the M gene is the key determinant of the cord-forming ability of influenza C viruses. Nucleotide sequence analysis of the M genes revealed that compared to C/Yamagata/1/88, C/Taylor/1233/47 had two amino acid substitutions in the M molecule at positions 24 (Ala → Thr) and 133 (Asp → Asn).

Influenza and pneumococcal vaccination of HIV-infected patients: A policy analysis

Objective: To analyze the policy of vaccinating human immunodeficiency virus (HTV)-infected young adults against influenza and pneumococcal infections. Methods: Transition state model of clinical immune deterioration of HIV infection, published data, and experts' estimates for the uncertain variables. Outcome measures are the number of influenza and pneumococcal infection hospitalizations and deaths prevented over 10 years and cost-effectiveness ratios. Patients: Hypothetical cohort of HIV-infected 30-year-old patients. Results: Although pneumococcal vaccine effectiveness diminishes with advanced HIV disease, the risks of pneumococcal infection rise substantially. Pneumococcal vaccination was therefore found to be a reasonable prevention strategy at all HIV disease stages: few vaccinations are needed to prevent hospitalizations and deaths, and the vaccination strategy is cost-effective. By contrast, influenza incidence is low among young adults, and HIV-related immunodeficiency increases influenza risks only minimally. Because the vaccine is administered yearly, many more vaccinations must be administered and fewer hospitalizations and deaths are prevented than with pneumococcal vaccination. The costs to extend life expectancy are high, and beyond the costs of other prevention strategies for persons with moderate to severe immunodeficiency. Conclusion: Pneumococcal vaccination is a reasonable prevention strategy for HIV-infected patients at all stages of immunodeficiency. Fewer hospitalizations and deaths are prevented by influenza vaccination, making it a far less cost-effective prevention strategy than pneumococcal vaccination.

Increasing influenza vaccination adherence through voice mail.

The number of influenza and influenza-related deaths is alarmingly high, yet mean vaccination adherence rates among the high-risk elderly population remain at only 20%. The present study investigates the use of an inexpensive voice-mail system, TeleMinder, as a method of increasing influenza vaccination adherence among a subpopulation of elders identified as low adherers. The first group of older people received no intervention. Group 2 received a voice-mail message informing them of the cost, time, date, and location of an influenza vaccination clinic. Group 3 was exposed to posted and verbal announcements alone. Group 4 both received voice mail and was exposed to posted and verbal announcements. Vaccination adherence levels for groups 1 through 4 were 1.5%, 11.8%, 7.4%, and 37.5%, respectively. Voice mail significantly increased vaccination adherence either alone or in combination with posted and verbal announcements. These findings suggest that voice mail provides an inexpensive means of increasing influenza vaccination rates.

Antigenic relationships between influenza B/Hong Kong/72 strains and B/Seattle/1/49

Pre-epidemic HI antibody against the B/Hong Kong/72 influenza virus was present in 34 to 70% of sera from persons aged more than 20 living in Saitama prefecture. The percentage of age-distribution of its antibody was the highest in persons aged 25-29 and high titers of its antibody were present in those persons too. These persons showed good correlation between their B/Hong Kong/72 and B/Seattle/1/49 antibodies. These findings suggest that the hemagglutinins of B/Hong Kong/72 virus are closely related to those of the B/Bon virus that prevailed in the 1943-52.B/Seattle/1/49 showed clear cross-reaction with B/Hong Kong/72 strains in hemagglutination inhibition tests with chicken antisera, and it was found by cross-absorption tests of HI antibodies in chicken antisera that the common antigen between B/Seattle/1/49, B/Yamagata/1/73 and B/Gifu/2/73 viruses was contained in major antigens of B/Hong Kong/72 viruses. However, the hemagglutinin of B/Osaka/2/70 did not contain this common antigenic factor.The findings constitute an example of antigenic recycling after a long period of abcence, and support the view that the number of influenza B virus is finite.

Influenza viruses: transmission between species.

The only direct evidence for transmission of influenza viruses between species comes from studies on swine influenza viruses. Antigenically and genetically identical Hsw1N1 influenza viruses were isolated from pigs and man on the same farm in Wisconsin, U.S.A. The isolation of H3N2 influenza viruses from a wide range of lower animals and birds suggests that influenza viruses of man can spread to the lower orders. Under some conditions the H3N2 viruses can persist for a number of years in some species. The isolation, from aquatic birds, of a large number of influenza A viruses that possess surface proteins antigenically similar to the viruses isolated from man, pigs and horses provides indirect evidence for inter-species transmission. There is now a considerable body of evidence which suggests that influenza viruses of lower animals and birds may play a role in the origin of some of the pandemic strains of influenza A viruses. There is no direct evidence that the influenza viruses in aquatic birds are transmitted to man, but they may serve as a genetic pool from which some genes may be introduced into humans by recombination. Preliminary evidence suggests that the molecular basis of host range and virulence may be related to the RNA segments coding for one of the polymerase proteins (P3) and for the nucleoprotein (NP).