531. Immunoglobulin G Response to Influenza A Nucleoprotein Following Vaccination in Adults and Children
Session: Poster Abstract Session: Influenza Vaccines
Friday, October 21, 2011
Room: Poster Hall B1
Background:  Influenza A vaccination is focused on generating neutralizing antibodies against hemagglutinin(HA) and neuraminidase (NA) surface proteins, but these undergo rapid antigenic change.  In contrast, the amino acid sequence of the internal nucleoprotein (NP) is >90% conserved among influenza A strains. Murine studies suggest that NP-specific antibody independently of T-cell immunity can enhance protection from influenza A. Influenza split trivalent influenza vaccine (TIV) is enriched for HA and NA, but also contains substantial amounts of “contaminating” NP. Anti-NP antibodies could have a protective role in humans, and it is unclear if split vaccines routinely induce these antibodies.

Methods: We measured NP-specific antibody by ELISA:  His-tagged NP of influenza A/PR8/34 or His-tagged HIV-1 p24 were expressed in E. coli and purified using a cobalt resin. ELISA plates were coated with purified NP or HIV p24 and incubated with serial dilutions of serum samples. An NP antibody positive human serum served as in internal standard. Wells were developed using HRP-conjugated mouse anti-human IgGand substrate. HIV p24 antibody reactivity, which was uniformly low, was used as a negative control and was subtracted from each anti-NP measurement.

Results: Paired sera from 7 adults (18-49 yrs of age) and 6 children (5-9 years of age) were tested prior to and one month post-TIV for NP antibodies. There was a statistically significant rise in titer 1 month post vaccination in adult patients (p= 0.035, two-tailed, paired t-test), whereas in children, the change in titer was not (p=0.086). Adults had a significantly higher basal level of NP antibody than children (p=0.005, two-tailed, unpaired t-test).

Conclusion:The NP “contaminant” inTIV induced a significant increase in the NP-specific IgG level in adults but not children, most likely because adults are primed by prior vaccinations and/ or natural infection. The findings raise the possibility that split vaccine induced antibodies against NP could potentially ameliorate influenza disease, especially in adults. Future studies evaluating the capacity of human anti-NP to provide protection in experimental viral challenge will be of interest.   

Subject Category: I. Adult and Pediatric Vaccines

Roshni Mathew, MD, Stanford University, Stanford, CA


R. Mathew, None

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