2202. Cytokine analysis and correlation to viral loads in a other-wise healthy population with influenza infection
Session: Poster Abstract Session: Host-Pathogen Interactions
Saturday, October 29, 2016
Room: Poster Hall
Posters
  • 2202_IDWPOSTER.pdf (162.7 kB)
  • Background:

    Studies suggest that the clinical characteristics of influenza A infection vary by subtype. We compared the virologic and immunologic characteristics of H1N1 vs. H3N2 infection, measuring viral load and serum cytokine concentration, among an otherwise healthy adult population.

    Methods:

    From 2010-2015, we conducted a longitudinal study of influenza-like illness (ILI) at five US military hospitals, enrolling 18-65y individuals without co-morbidities presenting for care <72h after illness onset. ILI was defined as a fever (≥100.4F) plus respiratory symptoms (cough, shortness of breath, or chest pain), with or without sore throat. Nasal and throat swabs and serum were collected on days 0, 3, 7, and 28. Influenza was detected by single-plex PCR, and viral load was determined by real-time RT-PCR. Serum cytokine concentrations were evaluated using a multiplex panel. Information on patient demographics, antiviral use, vaccine history and symptom severity was obtained by interview.

    Results:

    We analyzed 45 individuals, 21 with H1N1 and 24 with H3N2 infection. The majority of cases with H1N1 (67%) and H3N2 (71%) infection were enrolled in 2013-2014 and 2012-2013, respectively. The median (interquartile range [IQR]) age was 33y (29, 42) and did not differ by subtype. Fifty-one percent was male. Five (11%) were briefly hospitalized (duration: 1 day). Seventy-one percent had received influenza vaccine in the season of enrollment. Twenty one (47%) had been prescribed antivirals at the time of enrollment or shortly thereafter. Antiviral use was associated with a significant reduction in H1N1 (p=0.01), but not H3N2 (p=0.68), viral load. Among those not receiving antivirals (H1N1, n=11; H3N2, n=13), baseline viral load was higher among those with H3N2 infection (6 vs. 5 log copies per mL; p=0.006). There were no differences in viral load by subtype on days 3 or 7. The median concentrations of pro-inflammatory cytokines (e.g. IL-1β, IL-6, IL-8, MCP-1, IFN-γ) did not differ by subtype, at the baseline visit nor at subsequent visits. Neither viral load nor cytokine concentration was associated with symptom severity nor duration.

    Conclusion:

    In an otherwise healthy, predominantly outpatient, highly vaccinated adult population, viral load and pro-inflammatory cytokine concentration did not differ by influenza A subtype.

    Michelle Flores, MD1, Peifang Sun, PhD2, Wei-Ju Chen, PhD3, Mary Fairchok, MD4, John Arnold, MD5, Patrick Danaher, MD, FIDSA6, Tahaniyat Lalani, MD7, Michael Rajnik, MD8, Martin Ottolini, MD9, Erin Hansen, BS10, Maya Williams, PhD11, Jacqueline Owens Milzman, M.S.3, Michelande Ridore, MS3, Timothy Burgess, MD12 and Eugene Millar, PhD3, (1)Pediatrics, Walter Reed National Military Medical Center, Bethesda, MD, (2)Naval Medical Research Center, Silver Spring, MD, (3)Infectious Disease Clinical Research Program, Uniformed Services University of the Health Sciences, Bethesda, MD, (4)Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, (5)Naval Medical Center San Diego, San Diego, CA, (6)San Antonio Military Health System, Fort Sam Houston, TX, (7)Infectious Disease Clinical Research Program, Uniformed Services University of the Health Sciences, Rockville, MD, (8)Walter Reed National Military Medical Center, Bethesda, MD, (9)Uniformed Services University of the Health Sciences, Bethesda, MD, (10)Naval Health Research Center, San Diego, CA, (11)Viral and Rickettsial Diseases, Naval Medical Research Center, Silver Spring, MD, Peru, (12)Infectious Disease Clinical Research Program, Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD

    Disclosures:

    M. Flores, None

    P. Sun, None

    W. J. Chen, None

    M. Fairchok, None

    J. Arnold, None

    P. Danaher, None

    T. Lalani, None

    M. Rajnik, None

    M. Ottolini, None

    E. Hansen, None

    M. Williams, None

    J. Owens Milzman, None

    M. Ridore, None

    T. Burgess, None

    E. Millar, None

    Findings in the abstracts are embargoed until 12:01 a.m. CDT, Wednesday Oct. 26th with the exception of research findings presented at the IDWeek press conferences.