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Fulltext Cloning and expression of highly pathogenic avian influenza virus full-length nonstructural gene in Pichia pastoris

Abubakar MB, Aini I, Omar AR, Hair-Bejo M

J Biomed Biotechnol, 2011;2011:414198.
PMID: 21541235 DOI: 10.1155/2011/414198

Avian influenza (AI) is a highly contagious and rapidly evolving pathogen of major concern to the poultry industry and human health. Rapid and accurate detection of avian influenza virus is a necessary tool for control of outbreaks and surveillance. The AI virus A/Chicken/Malaysia/5858/2004 (H5N1) was used as a template to produce DNA clones of the full-length NS1 genes via reverse transcriptase synthesis of cDNA by PCR amplification of the NS1 region. Products were cloned into pCR2.0 TOPO TA plasmid and subsequently subcloned into pPICZαA vector to construct a recombinant plasmid. Recombinant plasmid designated as pPICZαA-NS1 gene was confirmed by PCR colony screening, restriction enzyme digestion, and nucleotide sequence analysis. The recombinant plasmid was transformed into Pichia pastoris GS115 strain by electroporation, and expressed protein was identified by SDS-PAGE and western blotting. A recombinant protein of approximately ~28 kDa was produced. The expressed protein was able to bind a rabbit polyclonal antibody of nonstructural protein (NS1) avian influenza virus H5N1. The result of the western blotting and solid-phase ELISA assay using H5N1 antibody indicated that the recombinant protein produced retained its antigenicity. This further indicates that Pichia pastoris could be an efficient expression system for a avian influenza virus nonstructural (NS1).

Matched MeSH terms: Influenza A Virus, H5N1 Subtype/genetics*; Influenza A Virus, H5N1 Subtype/pathogenicity*
Fulltext Monitoring of the h275y mutation in pandemic influenza A(H1N1) 2009 strains isolated in Malaysia

Suppiah J, Yusof MA, Othman KA, Saraswathy TS, Thayan R, Kasim FM, et al.

Southeast Asian J Trop Med Public Health, 2011 Jan;42(1):100-4.
PMID: 21323171

The 2009 pandemic influenza A(H1N1) infection in Malaysia was first reported in May 2009 and oseltamivir was advocated for confirmed cases in postexposure prophylaxis. However, there are cases of oseltamivir-resistance reported among H1N1-positive patients in other countries. Resistance is due to substitution of histidine by tyrosine at residue 275 (H275Y) of neuraminidase (NA). In this study, we have employed Sanger sequencing method to investigate the occurrence of mutations in NA segments of 67 pandemic 2009 A(H1N1) viral isolates from Malaysian patients that could lead to probable oseltamivir resistance. The sequencing analysis did not yield mutation at residue 275 for all 67 isolates indicating that our viral isolates belong to the wild type and do not confer resistance to oseltamivir.

Matched MeSH terms: Influenza A Virus, H1N1 Subtype/enzymology; Influenza A Virus, H1N1 Subtype/genetics*
Evaluation of the safety, reactogenicity and immunogenicity of FluBlok® trivalent recombinant baculovirus-expressed hemagglutinin influenza vaccine administered intramuscularly to healthy adults 50-64 years of age

Baxter R, Patriarca PA, Ensor K, Izikson R, Goldenthal KL, Cox MM

Vaccine, 2011 Mar 9;29(12):2272-8.
PMID: 21277410 DOI: 10.1016/j.vaccine.2011.01.039

Alternative methods for influenza vaccine production are needed to ensure adequate supplies.

Matched MeSH terms: Influenza A Virus, H1N1 Subtype/immunology; Influenza A Virus, H3N2 Subtype/immunology
Immunogenicity and tolerability of a virosome influenza vaccine compared to split influenza vaccine in patients with sickle cell anemia

Souza AR, Braga JA, de Paiva TM, Loggetto SR, Azevedo RS, Weckx LY

Vaccine, 2010 Jan 22;28(4):1117-20.
PMID: 20116631 DOI: 10.1016/j.vaccine.2009.05.046

The immunogenicity and tolerability of virosome and of split influenza vaccines in patients with sickle cell anemia (SS) were evaluated. Ninety SS patients from 8 to 34 years old were randomly assigned to receive either virosome (n=43) or split vaccine (n=47). Two blood samples were collected, one before and one 4-6 weeks after vaccination. Antibodies against viral strains (2006) A/New Caledonia (H1N1), A/California (H3N2), B/Malaysia were determined using the hemagglutinin inhibition test. Post-vaccine reactions were recorded over 7 days. Seroconversion rates for H1N1, H3N2 and B were 65.1%, 60.4% and 83.7% for virosome vaccine, and 68.0%, 61.7% and 68.0% for split vaccine. Seroprotection rates for H1N1, H3N2 e B were 100%, 97.6% and 69.7% for virosome, and 97.8%, 97.8% and 76.6% for split vaccine. No severe adverse reactions were recorded. Virosome and split vaccines in patients with sickle cell anemia were equally immunogenic, with high seroconversion and seroprotection rates. Both vaccines were well tolerated.

Matched MeSH terms: Influenza A Virus, H1N1 Subtype/immunology; Influenza A Virus, H3N2 Subtype/immunology
Avian Influenza Virus and DIVA Strategies

Hasan NH, Ignjatovic J, Peaston A, Hemmatzadeh F

Viral Immunol, 2016 05;29(4):198-211.
PMID: 26900835 DOI: 10.1089/vim.2015.0127

Vaccination is becoming a more acceptable option in the effort to eradicate avian influenza viruses (AIV) from commercial poultry, especially in countries where AIV is endemic. The main concern surrounding this option has been the inability of the conventional serological tests to differentiate antibodies produced due to vaccination from antibodies produced in response to virus infection. In attempts to address this issue, at least six strategies have been formulated, aiming to differentiate infected from vaccinated animals (DIVA), namely (i) sentinel birds, (ii) subunit vaccine, (iii) heterologous neuraminidase (NA), (iv) nonstructural 1 (NS1) protein, (v) matrix 2 ectodomain (M2e) protein, and (vi) haemagglutinin subunit 2 (HA2) glycoprotein. This short review briefly discusses the strengths and limitations of these DIVA strategies, together with the feasibility and practicality of the options as a part of the surveillance program directed toward the eventual eradication of AIV from poultry in countries where highly pathogenic avian influenza is endemic.

Matched MeSH terms: Influenza A virus/immunology*; Influenza A virus/isolation & purification; Influenza A virus/pathogenicity
Fulltext The burden of human influenza in Malaysia

Sam JIC

Med J Malaysia, 2015 Jun;70(3):127-30.
PMID: 26248773 MyJurnal

Seasonal and pandemic influenza causes considerable morbidity and mortality globally, but the burden of disease is understudied and underreported in developing countries such as Malaysia. Before considering the cost-effectiveness of introducing interventions such as vaccines to control influenza, it is imperative to determine clinical and socioeconomic impact of the disease. This review summarises the main available literature on human influenza in Malaysia, the possible reasons for the lack of study and awareness of influenza, and important knowledge gaps for future study.

Matched MeSH terms: Influenza A Virus, H1N1 Subtype
Silver linings: a qualitative study of desirable changes to cancer care during the COVID-19 pandemic

Lombe D, Sullivan R, Caduff C, Ali Z, Bhoo-Pathy N, Cleary J, et al.

Ecancermedicalscience, 2021;15:1202.
PMID: 33889211 DOI: 10.3332/ecancer.2021.1202

Introduction: Public health emergencies and crises such as the current COVID-19 pandemic can accelerate innovation and place renewed focus on the value of health interventions. Capturing important lessons learnt, both positive and negative, is vital. We aimed to document the perceived positive changes (silver linings) in cancer care that emerged during the COVID-19 pandemic and identify challenges that may limit their long-term adoption.
Methods: This study employed a qualitative design. Semi-structured interviews (n = 20) were conducted with key opinion leaders from 14 countries. The participants were predominantly members of the International COVID-19 and Cancer Taskforce, who convened in March 2020 to address delivery of cancer care in the context of the pandemic. The Framework Method was employed to analyse the positive changes of the pandemic with corresponding challenges to their maintenance post-pandemic.
Results: Ten themes of positive changes were identified which included: value in cancer care, digital communication, convenience, inclusivity and cooperation, decentralisation of cancer care, acceleration of policy change, human interactions, hygiene practices, health awareness and promotion and systems improvement. Impediments to the scale-up of these positive changes included resource disparities and variation in legal frameworks across regions. Barriers were largely attributed to behaviours and attitudes of stakeholders.
Conclusion: The COVID-19 pandemic has led to important value-based innovations and changes for better cancer care across different health systems. The challenges to maintaining/implementing these changes vary by setting. Efforts are needed to implement improved elements of care that evolved during the pandemic.

Matched MeSH terms: Influenza A Virus, H1N1 Subtype
Fulltext Decaffeination and Neuraminidase Inhibitory Activity of Arabica Green Coffee (Coffea arabica) Beans: Chlorogenic Acid as a Potential Bioactive Compound

Muchtaridi M, Lestari D, Khairul Ikram NK, Gazzali AM, Hariono M, Wahab HA

Molecules, 2021 Jun 04;26(11).
PMID: 34199752 DOI: 10.3390/molecules26113402

Coffee has been studied for its health benefits, including prevention of several chronic diseases, such as type 2 diabetes mellitus, cancer, Parkinson's, and liver diseases. Chlorogenic acid (CGA), an important component in coffee beans, was shown to possess antiviral activity against viruses. However, the presence of caffeine in coffee beans may also cause insomnia and stomach irritation, and increase heart rate and respiration rate. These unwanted effects may be reduced by decaffeination of green bean Arabica coffee (GBAC) by treatment with dichloromethane, followed by solid-phase extraction using methanol. In this study, the caffeine and chlorogenic acid (CGA) level in the coffee bean from three different areas in West Java, before and after decaffeination, was determined and validated using HPLC. The results showed that the levels of caffeine were reduced significantly, with an order as follows: Tasikmalaya (2.28% to 0.097% (97 ppm), Pangalengan (1.57% to 0.049% (495 ppm), and Garut (1.45% to 0.00002% (0.2 ppm). The CGA levels in the GBAC were also reduced as follows: Tasikmalaya (0.54% to 0.001% (118 ppm), Pangalengan (0.97% to 0.0047% (388 ppm)), and Garut (0.81% to 0.029% (282 ppm). The decaffeinated samples were then subjected to the H5N1 neuraminidase (NA) binding assay to determine its bioactivity as an anti-influenza agent. The results show that samples from Tasikmalaya, Pangalengan, and Garut possess NA inhibitory activity with IC50 of 69.70, 75.23, and 55.74 μg/mL, respectively. The low level of caffeine with a higher level of CGA correlates with their higher levels of NA inhibitory, as shown in the Garut samples. Therefore, the level of caffeine and CGA influenced the level of NA inhibitory activity. This is supported by the validation of CGA-NA binding interaction via molecular docking and pharmacophore modeling; hence, CGA could potentially serve as a bioactive compound for neuraminidase activity in GBAC.

Matched MeSH terms: Influenza A Virus, H5N1 Subtype/drug effects; Influenza A Virus, H5N1 Subtype/enzymology*; Influenza A Virus, H5N1 Subtype/chemistry
Fulltext Community awareness and attitudes towards influenza outbreak and prevention in Serian, Sarawak

Rohaya Mohd-Nor, Rose Nanju@Manju, Samuel Lihan, Sidiah John Siop, Rekaya Vincent Balang, Constance Rinen Justin Wah, et al.

Int J Public Health Res, 2013;3(2):334-346.
MyJurnal

To date, there has been no systematic research that investigates the rural community awareness and attitudes towards pandemic influenza H1N1 and its prevention measures in the context of Sarawak. There is also no systematic study about whether the initiatives to educate the public undertaken by the government and other agencies have empowered the rural communities to practice an effective self-care within the context of community, that assist to curb the potential spread of this disease. Our research aims to address these limitations. In this paper, we report a survey finding about the awareness and attitudes of the Serian community with regard to this area of research interest. We also investigate the relevant sources of information that the community relies on in understanding about the influenza and how it can spread. Overall, the outcomes of the survey reveal that a majority of our respondents has a relatively low level of knowledge and awareness particularly about the characteristics of the illness and how H1N1 virus can transmit. With regard to prevention measures, a majority of them reported good understanding and awareness about the effective self-care practices that can help to curb the potential spread of the influenza. The top five sources to obtain information about the influenza were: information from family, relatives, friends or neighbours; radio; TV; newspapers; and government health talk seminar or campaigns. The research outcomes can offer pragmatic contributions that can benefit the health campaigners and policy makers.

Matched MeSH terms: Influenza A Virus, H1N1 Subtype
Fulltext Tracking the source and origin of H5N1 avian influenza viruses in Malaysia

Sharifah, S .H., Suriani, M. N., Hassuzana, K., Aini, I.

Buletin Persatuan Genetik Malaysia, 2006;12(1):1-3.
MyJurnal

Malaysia, experienced two epidemic waves of HPAI; its fi rst outbreak of HP H5N1 in August 2004 that occurred in the state of Kelantan and the second and subsequent outbreaks in February–March 2006 in three states on the west coast of Malaysia namely Wilayah Persekutuan
Kuala Lumpur, Perak and Penang. Five outbreaks occurred in village chickens and one in a multi-species enclosure of birds in a bird park resort facility. Molecular epidemiological studies by genomic sequencing and phylogenetic analyses of the viruses isolated showed that the
virus isolated from WP Kuala Lumpur is of the V-genotype and it originated from Hunan China, two viruses were found to be similar to the Fujian/Hunan strains and other viruses were similar to the Vietnam/ Thailand strains.

Matched MeSH terms: Influenza A Virus, H5N1 Subtype
Insertion of single-chain variable fragment (scFv) peptide linker improves surface display of influenza hemagglutinin (HA1) on non-recombinant Lactococcus lactis

Jee PF, Chen FS, Shu MH, Wong WF, Abdul Rahim R, AbuBakar S, et al.

Biotechnol Prog, 2017 Jan;33(1):154-162.
PMID: 27802566 DOI: 10.1002/btpr.2400

Heterologous protein displayed on the surface of Lactococcus lactis using the binding domain of N-acetylmuramidase (AcmA) has a potential application in vaccine delivery. In this study, we developed a non-recombinant L. lactis surface displaying the influenza A (H1N1) 2009 hemagglutinin (HA1). Three recombinant proteins, HA1/L/AcmA, HA1/AcmA, and HA1 were overexpressed in Escherichia coli, and purified. In the binding study using flow cytometry, the HA1/L/AcmA, which contained the single-chain variable fragment (scFv) peptide linker showed significantly higher percentage of binding counts and mean fluorescence binding intensity (MFI) (51.7 ± 1.4% and 3,594.0 ± 675.9, respectively) in comparison to the HA1/AcmA without the scFv peptide linker (41.1 ± 1.5% and 1,652.0 ± 34.1, respectively). Higher amount of HA1/L/AcmA (∼2.9 × 10(4) molecules per cell) was displayed on L. lactis when compared to HA1/AcmA (∼1.1 × 10(4) molecules per cell) in the immunoblotting analysis. The HA1/L/AcmA completely agglutinated RBCs at comparable amount of protein to that of HA1/AcmA and HA1. Computational modeling of protein structures suggested that scFv peptide linker in HA1/L/AcmA kept the HA1 and the AcmA domain separated at a much longer distance in comparison to HA1/AcmA. These findings suggest that insertion of the scFv peptide linker between HA1 and AcmA improved binding of recombinant proteins to L. lactis. Hence, insertion of scFv peptide linker can be further investigated as a potential approach for improvement of heterologous proteins displayed on the surface of L. lactis using the AcmA binding domain. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:154-162, 2017.

Matched MeSH terms: Influenza A Virus, H1N1 Subtype
Seasonal influenza activity based on laboratory surveillance in Malaysia, 2011-2016

Sam IC, Noraini W, Sandhu SS, Norizah I, Selvanesan S, Thayan R, et al.

J Med Virol, 2019 03;91(3):498-502.
PMID: 30199092 DOI: 10.1002/jmv.25313

Influenza seasonality in equatorial countries is little understood. Seasonal and alert influenza thresholds were determined for Malaysia, using laboratory-based data obtained from the Malaysia Influenza Surveillance System and a major teaching hospital, from 2011 to 2016. Influenza was present year-round, with no clear annual seasons. Variable periods of higher transmission occurred inconsistently, in November to December, January to March, July to September, or a combination of these. These coincide with seasons in the nearby southeast Asian countries or winter seasons of the northern and southern hemispheres. Changes in the predominant circulating influenza type were only sometimes associated with increased transmission. The data can provide public health interventions such as vaccines.

Matched MeSH terms: Influenza A virus
Fulltext Universal oral vaccine for influenza infections

Yap, Wei Boon, Toong, Seng Tan, Sharifah Syed Hassan, Jeffrey Cheah

Jurnal Sains Kesihatan Malaysia, 2018;16(2):51-64.
MyJurnal

Each year, influenza A infections have caused tremendous death rate as high as 300,000-500,000 globally. Although
there are effective anti-influenza agents and vaccines, high mutational rate among influenza A viruses renders dramatic
decline in the effectiveness of anti-influenza agents or vaccines in certain individuals. The situation is further complicated
by limitations in influenza vaccine production, for instance, long production period, limited vaccine capacity and lack
of cross-protection against various influenza A virus strains. To solve these issues, development of universal influenza
vaccine based on conserved antigens such as non-stuctural protein 1 (NS1) has been endeavoured. NS1 protein is highly
conserved in all influenza A virus strains known by far, produced abundantly on infected cell surfaces and responsible for
maintaining virulence. Furthermore, cytotoxic T-lymphocytes that are active against NS1 were also reported to be able
to avoid shedding of influenza in hosts. To better inhibit influenza infections, oral immunization has long been proposed
due to feasibility of this method to be implemented and safer for recipients while able to target influenza A viruses from
the entry point. Lactobacillus has been vastly studied for its roles as bacterial carrier in oral vaccine development due
to its significant probiotic properties. For examples, stimulation of immune responses in oral and airway mucosal layers,
high colonization in oral and airway mucosal layers and great natural adjuvant effects. In this light, influenza universal
oral vaccine developed using NS1 dan Lactobacillus should be further studied in influenza oral vaccine design.

Matched MeSH terms: Influenza A virus
Assessment of efficacy of Oseltamivir-Azithromycin combination therapy in prevention of Influenza-A (H1N1)pdm09 infection complications and rapidity of symptoms relief

Ishaqui AA, Khan AH, Sulaiman SAS, Alsultan MT, Khan I, Naqvi AA

Expert Rev Respir Med, 2020 05;14(5):533-541.
PMID: 32053044 DOI: 10.1080/17476348.2020.1730180

Objectives: This study aimed to assess the efficacy of oseltamivir-Azithromycin combination therapy for prevention of Influenza-A (H1N1)pdm09 infection associated complications and early relief of influenza symptoms.Methods: In a retrospective observational cohort study, Influenza-A (H1N1)pdm09 infection hospitalized patients were identified and divided into two groups based on the initial therapy. Group-AV patients were initiated on Oseltamivir without any antibiotic in treatment regimen while Group-AV+AZ patients were initiated on Oseltamivir and Azithromycin combination therapy for at least 3-5 days. Patients were evaluated for different clinical outcomes.Results: A total of 227 and 102 patients were identified for Group-AV and Group-AV+AZ respectively. Multivariate regression analysis showed that incidences of secondary bacterial infections were significantly less frequent (23.4% vs 10.4%; P-value = 0.019) in Group-AV+AZ patients. Group-AV+AZ patients were associated with shorter length of hospitalization (6.58 vs 5.09 days; P-value = <0.0001) and less frequent incidences of respiratory support (38.3% vs 17.6%; P-value = 0.016). Overall influenza symptom severity score was statistically significant less for Group-AV+AZ patients on Day-5 (10.68 ± 2.09; P-value = 0.001) of hospitalization.Conclusion: Oseltamivir-Azithromycin combination therapy was found to be more efficacious as compared to oseltamivir alone in rapid recovery and prevention of Influenza associated complications especially in high risk patients.

Matched MeSH terms: Influenza A Virus, H1N1 Subtype
Fulltext A cell-based screening system for anti-influenza A virus agents

Wong WY, Loh SW, Ng WL, Tan MC, Yeo KS, Looi CY, et al.

Sci Rep, 2015;5:8672.
PMID: 25728279 DOI: 10.1038/srep08672

Emerging of drug resistant influenza A virus (IAV) has been a big challenge for anti-IAV therapy. In this study, we describe a relatively easy and safe cell-based screening system for anti-IAV replication inhibitors using a non-replicative strain of IAV. A nickel (II) complex of polyhydroxybenzaldehyde N4-thiosemicarbazone (NiPT5) was recently found to exhibit anti-inflammatory activity in vivo and in vitro. NiPT5 impedes the signaling cascades that lead to the activation of NF-κB in response to different stimuli, such as LPS and TNFα. Using our cell-based screening system, we report that pretreating cells with NiPT5 protects cells from influenza A virus (IAV) and vesicular stomatitis virus (VSV) infection. Furthermore, NiPT5 inhibits replication of IAV by inhibiting transcription and translation of vRNAs of IAV. Additionally, NiPT5 reduces IAV-induced type I interferon response and cytokines production. Moreover, NiPT5 prevents activation of NF-κB, and IRF3 in response to IAV infection. These results demonstrate that NiPT5 is a potent antiviral agent that inhibits the early phase of IAV replication.

Matched MeSH terms: Influenza A virus/drug effects*
Fulltext Prophylactic effect of herbal-marine compound (HESA-A) on influenza A virus infectivity

Mehrbod P, Ideris A, Omar AR, Hair-Bejo M

BMC Complement Altern Med, 2014;14:131.
PMID: 24708698 DOI: 10.1186/1472-6882-14-131

Influenza virus is still a severe respiratory disease affecting human and other species. As conventional drugs are not recommended for long time because of side effects and drug resistance occurrence, traditional medication has been focused as alternative remedy. HESA-A is a natural compound from herbal-marine origin. Previous studies have reported the therapeutic properties of HESA-A on psoriasis vulgaris and different types of cancers and we also showed its anti-inflammatory effects against influenza A infection.

Matched MeSH terms: Influenza A virus/drug effects*
Fulltext Immunogenicity and safety of quadrivalent versus trivalent inactivated influenza vaccine: a randomized, controlled trial in adults

Beran J, Peeters M, Dewé W, Raupachová J, Hobzová L, Devaster JM

BMC Infect Dis, 2013;13:224.
PMID: 23688546 DOI: 10.1186/1471-2334-13-224

Two phylogenetic lineages of influenza B virus coexist and circulate in the human population (B/Yamagata and B/Victoria) but only one B-strain is included in each seasonal vaccine. Mismatch regularly occurs between the recommended and circulating B-strain. Inclusion of both lineages in vaccines may offer better protection against influenza.

Matched MeSH terms: Influenza A virus/immunology
Fulltext A case of acute respiratory distress syndrome associated with novel H1N1 treated with intravenous immunoglobulin G

Chong JL, Sapari S, Kuan YC

J Microbiol Immunol Infect, 2011 Aug;44(4):319-22.
PMID: 21524955 DOI: 10.1016/j.jmii.2010.07.001

Influenza A "novel H1N1" with severe acute respiratory distress syndrome (ARDS) is a serious illness that poses a challenge to clinicians managing such cases. This case report reveals a patient with ARDS secondary to influenza A with deteriorating clinical status, who improved tremendously after intravenous immunoglobulin G (IV IgG). Patients with H1N1 associated with ARDS may be given a trial of IV IgG. More case reports and trials are required to ascertain the efficacy of IV IgG and the best dosage and timing of starting IV IgG in relation to antiviral therapy.

Matched MeSH terms: Influenza A Virus, H1N1 Subtype/isolation & purification*
Representations of swine flu: perspectives from a Malaysian pig farm

Goodwin R, Haque S, Hassan SB, Dhanoa A

Public Underst Sci, 2011 Jul;20(4):477-90.
PMID: 21936262

Novel influenza viruses are seen, internationally, as posing considerable health challenges, but public responses to such viruses are often rooted in cultural representations of disease and risk. However, little research has been conducted in locations associated with the origin of a pandemic. We examined representations and risk perceptions associated with swine flu amongst 120 Malaysian pig farmers. Thirty-seven per cent of respondents felt at particular risk of infection, two-thirds were somewhat or very concerned about being infected. Those respondents who were the most anxious believed particular societal "out-groups" (homosexuals, the homeless and prostitutes) to be at higher infection risk. Although few (4%) reported direct discrimination, 46% claimed friends had avoided them since the swine flu outbreak. Findings are discussed in the context of evolutionary, social representations and terror management theories of response to pandemic threat.

Matched MeSH terms: Influenza A Virus, H1N1 Subtype*
Fulltext Cellular immune responses to recurring influenza strains have limited boosting ability and limited cross-reactivity to other strains

Keynan Y, Card CM, Ball BT, Li Y, Plummer FA, Fowke KR

Clin Microbiol Infect, 2010 Aug;16(8):1179-86.
PMID: 20670292 DOI: 10.1111/j.1469-0691.2010.03142.x

Influenza vaccine provides protection against infection with matched strains, and this protection correlates with serum antibody titres. In addition to antibodies, influenza-specific CD8+ T-lymphocyte responses are important in decreasing disease severity and facilitating viral clearance. Because this response is directed at internal, relatively conserved antigens, it affords some cross-protection within a given subtype of influenza virus. With the possibility of a broader A(H1N1) Mexico outbreak in the fall of 2009, it appeared worthwhile studying the degree of cellular immune response-mediated cross-reactivity among influenza virus isolates. The composition of the 2006-2007 influenza vaccine included the A/New Caledonia/20/1999 strain (comprising a virus that has been circulating, and was included in vaccine preparations, for 6-7 years) and two strains not previously included (Wisconsin and Malaysia). This combination afforded us the opportunity to determine the degree of cross-reactive cellular immunity after exposure to new viral strains. We analysed the antibody responses and the phenotype and function of the T cell response to vaccine components. The results obtained show that antibody responses to A/New-Caledonia were already high and vaccination did not increase antibody or cytotoxic T lymphocyte responses. These data suggest that repeated exposure to the same influenza stain results in limited boosting of humoral and cellular immune responses.

Matched MeSH terms: Influenza A virus/immunology*

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