ABSTRACT We established a rapid method for the identification of influenza A and B virus strains: the peroxidase-antiperoxidase (PAP) staining method with two subtype-specific murine monoclonal antibodies, C179 (H1 and H2 specific) and F49 (H3 specific), and an anti-influenza B virus rabbit polyclonal serum. The types and subtypes of 160 strains were examined, and 158 strains were identified to be the same by the hemagglutination-inhibition (HI) test and the PAP method. In contrast to the results by the HI test, two strains were revealed to be a mixture of two subtypes (H1 and H3) by the PAP method, which was confirmed by plaque cloning. We further analyzed clinical specimens by the PAP method by directly inoculating specimens into Madin-Darby canine kidney cells in microplates. After 40 h of incubation, the types and subtypes of viruses in 52 of 152 specimens were clearly identified. Since the reactivities of the two monoclonal antibodies are not influenced by the antigenic drift of influenza virus, the newly developed method should be applicable not only for rapid diagnosis but also for the epidemiological study of influenza.
Although annual influenza vaccination is an important strategy used to prevent influenza-related morbidity and mortality, some studies have reported the negative influence of prior vaccination on vaccine effectiveness (VE) for current seasons. Currently, the influence of prior vaccination is not conclusive, especially in children.We evaluated the association between current-season VE and prior season vaccination using a test-negative design in children aged 1-5 years presenting at nine outpatient clinics in Japan during the 2016/17 and 2017/18 influenza seasons. Children with influenza-like illness were enrolled prospectively and tested for influenza using real-time RT-PCR. Their recent vaccination history was categorized into six groups according to current vaccination doses (0/1/2) and prior vaccination status (unvaccinated = 0 doses/vaccinated = 1 dose or 2 doses): (1) 0 doses in the current season and unvaccinated in prior seasons (reference group); (2) 0 doses in the current season and vaccinated in a prior season; (3) 1 dose in the current season and unvaccinated in a prior season; (4) 1 dose in the current season and vaccinated in a prior season; (5) 2 doses in the current season and unvaccinated in a prior season, and (6) 2 doses in the current season and vaccinated in a prior season.A total of 799 cases and 1196 controls were analyzed. The median age of the subjects was 3 years, and the proportion of males was 54%. Overall, the vaccination rates (any vaccination in the current season) in the cases and controls were 36% and 53%, respectively. The VEs of the groups were: (2) 29% (95% confidence interval: -25% to 59%); (3) 53% (6% to 76%); (4) 70% (45% to 83%); (5) 56% (32% to 72%), and (6) 61% (42% to 73%). The one- and two-dose VEs of the current season were significant regardless of prior vaccination status. The results did not differ when stratified by influenza subtype/lineage.Prior vaccination did not attenuate the current-season VE in children aged 1 to 5 years, supporting the annual vaccination strategy.
Infants <6 months of age are too young to receive influenza vaccine, despite being at high risk for severe influenza-related complications.To examine the effectiveness of maternal influenza vaccination in preventing influenza in their infants, we conducted a prospective cohort study of 3441 infants born at participating hospitals before the 2013-2014 influenza season. At the time of recruitment, their mothers completed a questionnaire about influenza vaccination status for the 2013-2014 season. A follow-up survey was conducted after the end of the 2013-2014 season to collect information regarding influenza diagnosis and hospitalization among infants.During the 2013-2014 influenza season, 71 infants (2%) had influenza diagnosed, and 13 infants (0.4%) were hospitalized with influenza. Maternal influenza vaccination (especially prenatal vaccination) decreased the odds of influenza among infants. The effectiveness of prenatal vaccination was 61% (95% confidence interval, 16%-81%), whereas that of postpartum vaccination was 53% (-28%-83%). Although maternal influenza vaccination was also associated with a decreased odds of influenza-related hospitalization among infants, vaccine effectiveness (73%) did not reach statistical significance, owing to the limited number of infants hospitalized because of influenza.The present findings indicated that pregnant women and postpartum women should receive influenza vaccination to protect their infants.
A novel recombinant human adenovirus (HAdV) species D was isolated from the stool of a pharyngitis patient in Japan and genetic characterization was performed by sequencing variable regions between HAdV types. The nucleotide sequences of the penton base gene and loops 1 and 2 in the hexon gene showed 100% identity with that of the recently identified HAdV-56. Although we observed greatest identity for the entire hexon gene sequence with that of HAdV-56, we noted even greater similarity between the partial nucleotide sequence of the conserved region 4 and that of HAdV-37. Furthermore, the fibre gene and early region 3 sequences were completely identical to that of HAdV-37. These results suggest that the strain is a novel adenovirus related to HAdV-37 and HAdV-56.
