Recombinant IAV H3N2 (A/Pennsylvania/14/2010) Hemagglutinin (a.a. 17-345) [His]

We conducted a prospective, multicenter, non-randomized observational study to assess the duration of fever and symptoms of influenza A/H1N1pdm09 and A/H3N2 infected children < 19 years old treated with either baloxavir or oseltamivir. Additionally, these symptoms were investigated in association with pre- and post-baloxavir treatment-emergent polymerase acidic unit (PA) variants as compared to non-substituted viruses. Following receipt of informed consent, baloxavir was administered to 102 influenza A patients, and oseltamivir to 52 patients during the 2018-2019 influenza season in Japan. The average age was higher in the baloxavir treatment group compared to the oseltamivir treatment group (10.6 +/- 2.7 versus 6.9 +/- 2.9 years old, p < 0.01). The duration of fever and symptoms in baloxavir-treated A/H1N1pdm09 and A/H3N2-infected children did not differ from those in oseltamivir-treated groups (median 22.0, 11.8, 23.0, and 21.0 h, and median 114.5, 121.0, 123.0, and 122.0 h, respectively). One (1.2%) of 83 A/H3N2 patients possessed a PA/I38T substituted virus prior to treatment. The frequency of PA variants in post-treatment samples obtained 2-11 days after beginning of baloxavir was 12.5% (4/32) for A/H1N1pdm09 and 14.1% (9/64) for A/H3N2 when the total number of cases was used as the denominator, however, were 57.1% (4/7) and 33.3% (9/27) when PCR-positive cases at the time of second sampling was used as the denominator. The most frequent PA substitution was I38T (9), with E23K (1), I38K (1), I38M (1), and PA/I38S (1) also observed. The duration of fever and overall symptoms did not differ significantly following baloxavir treatment in individuals with PA variant viruses, non-substituted virus, or in those that were PCR negative at the second sampling (median 20, 24 and 11 h, and median 121, 115 and 121 h, respectively). Rebound of viral RNA load was observed in 13.5% (2/13) of PA variants but it was not associated with recurrence of fever and symptoms. Hence, prolonged fever or symptoms were not observed in children treated with baloxavir following emergence of PA variants, however, further studies are needed to evaluate the clinical impact of PA variants.

Conventional influenza vaccines need to be designed and manufactured yearly. However, they occasionally provide poor protection owing to antigenic mismatch. Hence, there is an urgent need to develop universal vaccines against influenza virus. Using nucleoprotein (NP) and extracellular domain of matrix protein 2 (M2e) genes from the influenza A virus A/Beijing/30/95 (H3N2), we constructed four recombinant vaccinia virus-based influenza vaccines carrying NP fused with one or four copies of M2e genes in different orders. The recombinant vaccinia viruses were used to immunize BALB/C mice. Humoral and cellular responses were measured, and then the immunized mice were challenged with the influenza A virus A/Puerto Rico/8/34 (PR8). NP-specific humoral response was elicited in mice immunized with recombinant vaccinia viruses carrying full-length NP, while robust M2e-specific humoral response was elicited only in the mice immunized with recombinant vaccinia viruses carrying multiple copies of M2e. All recombinant viruses elicited NP- and M2e-specific cellular immune responses in mice. Only immunization with RVJ-4M2eNP induced remarkably higher levels of IL-2 and IL-10 cytokines specific to M2e. Furthermore, RVJ-4M2eNP immunization provided the highest cross-protection in mice challenged with 20 MLD50 of PR8. Therefore, the cross-protection potentially correlates with both NP and M2e-specific humoral and cellular immune responses induced by RVJ-4M2eNP, which expresses a fusion antigen of full-length NP preceded by four M2e repeats. These results suggest that the rational fusion of NP and multiple M2e antigens is critical toward inducing protective immune responses, and the 4M2eNP fusion antigen may be employed to develop a universal influenza vaccine.