Susceptibility of epidemic viruses to neuraminidase inhibitors and treatment-emergent resistance in the Japanese 2019-20 influenza season

OBJECTIVES

To investigate the susceptibility of epidemic influenza viruses to neuraminidase inhibitors (NAIs) and the emergence of resistant viruses after treatment, a prospective, observational study was done in the 2019-20 Japanese influenza season.

METHODS

Influenza viruses were isolated before and twice after treatment, the first at day 5 and the second at day 10. The 50% inhibitory concentrations (IC₅₀s) to oseltamivir, zanamivir, peramivir, and laninamivir were measured and compared with those of 2010-11 to 2018-19 seasons. NA amino acid sequences were analyzed by next generation sequencing (NGS).

RESULTS

The IC₅₀ geometric means of the NAIs for 128 A(H1N1)pdm09, 2 A(H3N2), and 33 B were comparable to those of the previous seasons. Only 2 (1.6%) A(H1N1)pdm09 with significantly high IC₅₀ to oseltamivir were found pretreatment. No A(H3N2) or B had resistance. Treatment-emergent oseltamivir resistance was found in 2 among 33 oseltamivir-treated A(H1N1)pdm09, only at the second follow-up. The NGS indicated a rapid increase in the proportion of H275Y to wild type, from 0% to almost 100% between days 5 and 10.

CONCLUSIONS

These results suggest the continued effectiveness of these NAIs for epidemic influenza in Japan. Treatment-emergent resistant H275Y A(H1N1)pdm09 viruses were detected after oseltamivir treatment, rapidly replacing the wild type.

In vitro neuraminidase inhibitory concentration (IC50) of four neuraminidase inhibitors in the Japanese 2017-18 season: Comparison with the 2010-11 to 2016-17 seasons

To assess the extent of susceptibility to the four most commonly used neuraminidase inhibitors (NAIs) of the viruses epidemic in the 2017-18 Japanese influenza season, we measured the 50% inhibitory concentration (IC₅₀) for influenza virus isolates from patients and compared them with the results from the 2010-11 to 2016-17 seasons. Viral isolation was done with specimens obtained prior to treatment, and the type and subtype was determined by RT-PCR using type- and subtype-specific primers. The IC₅₀ was determined by a neuraminidase inhibition assay using a fluorescent substrate. A total of 237 virus isolates, 50 A(H1N1)pdm09, 92 A(H3N2), and 95 B were measured. No A(H1N1)pdm09 with highly reduced sensitivity for oseltamivir was found in the 2017-18 season. No isolates with highly reduced sensitivity to the four NAIs have been found for A(H3N2) or B from the 2010-11 to 2017-18 seasons. The geometric mean IC₅₀s of the four NAIs were quite consistent during the eight studied seasons. These results indicate that the sensitivity to the four commonly used NAIs has been maintained.

Duration of fever and other symptoms after the inhalation of laninamivir octanoate hydrate in the 2016/17 Japanese influenza season; comparison with the 2011/12 to 2015/16 seasons

The duration of fever and symptoms after laninamivir octanoate hydrate (laninamivir) inhalation were investigated in the Japanese 2016/17 influenza season and the results were compared with those of the 2011/12 to 2015/16 seasons. A total of 1278 patients were evaluated for the duration of fever and symptoms in the six studied seasons. In the 2016/17 season, the influenza types/subtypes of the patients were 6 A (H1N1)pdm09 (2.9%), 183 A (H3N2) (87.6%), and 20 B (9.6%). The respective median durations of fever for A (H1N1)pdm09, A (H3N2), and B were 38.0, 33.0, and 38.5 h, without significant difference (p = 0.9201), and the median durations of symptoms were 86.5, 73.0, and 99.0 h, with significant difference (p = 0.0342). The median durations of fever and symptoms after laninamivir inhalation were quite consistent for the six studied seasons for A (H1N1)pdm09, A (H3N2), and B, without any significant differences. The percentage of patients with unresolved fever patients displayed a similar pattern through the six studied seasons for all these virus types. There was no significant difference in the duration of fever or symptoms between the Victoria and Yamagata lineages in the 2016/17 season and those of the previous studied seasons. Over the seasons tested, ten adverse drug reactions (ADRs) were reported from 1341 patients. The most frequent ADR was diarrhea and all ADRs were self-resolving and not serious. These results indicate the continuing clinical effectiveness of laninamivir against influenza A (H1N1)pdm09, A (H3N2), and B, with no safety issues.

In vitro neuraminidase inhibitory concentration (IC50) of four neuraminidase inhibitors in the Japanese 2016-17 season: Comparison with the 2010-11 to 2015-16 seasons

To assess the extent of susceptibility to the four most commonly used neuraminidase inhibitors (NAIs) in the viruses epidemic in the 2016-17 Japanese influenza season, we measured the 50% inhibitory concentration (IC₅₀) of these NAIs for influenza virus isolates from patients and compared them with the results from the 2010-11 to 2015-16 seasons. Viral isolation was done with specimens obtained prior to treatment, and the type and subtype was determined by RT-PCR using type- and subtype-specific primers. The IC₅₀ was determined by a neuraminidase inhibition assay using a fluorescent substrate. A total of 276 virus isolates, 6 A (H1N1)pdm09 (2.2%), 249 A (H3N2) (90.2%), and 21 B (7.6%), had the IC₅₀ measured for the four NAIs. B isolates included 11 (52.4%), 9 (42.9%), and one (4.8%) of the Victoria, Yamagata, and undetermined strains, respectively. No A (H1N1)pdm09 with highly reduced sensitivity for oseltamivir was found in the 2016-17 season. No isolate with highly reduced sensitivity to the four NAIs have been found for A (H3N2) or B from the 2010-11 to 2016-17 seasons. No significant trend of increase or decrease was found in the geometric mean IC₅₀s of the four NAIs during the seven studied seasons. These results indicate that the sensitivity to the four commonly used NAIs has been maintained and that any change in the effectiveness of these NAIs would be minute. Common usage of NAIs for patient treatment has not been a driving force in the selection of NAI resistant viruses.

Duration of fever and other symptoms after the inhalation of laninamivir octanoate hydrate for influenza treatment; comparison among the four Japanese influenza seasons from 2011-2012 to 2014-2015

The duration of fever and other symptoms as markers of the clinical effectiveness of laninamivir octanoate hydrate (laninamivir) were investigated in the Japanese 2014-2015 influenza season and the results were compared with those of the previous three seasons, 2011-2012 to 2013-2014. From these four seasons, the data of 636 influenza A(H3N2) and 128 influenza B patients was available for analysis. No significant difference was found in their baseline characteristics. The median duration of fever for all A(H3N2) patients ranged from 32.0 to 41.0 h. The duration of fever in the 2014-2015 season was significantly shorter than that in the 2012-2013 and 2013-2014 seasons (p = 0.0204 and 0.0391, respectively), but the differences were within nine hours. The median duration of symptoms for A(H3N2) ranged from 80.0 to 89.0 h, with no significant difference among the four seasons (p = 0.2222). The median duration of fever for B patients ranged from 43.0 to 50.0 h, with no significant difference among the four seasons. The duration of the symptoms for B varied by season, but no significant difference was found among the four seasons. Over the four seasons, 44 adverse events were reported from among 921 patients, with all resolving without treatment. These results indicate the continuing effectiveness of laninamivir against influenza A(H3N2) and B, with no safety issues. It is unlikely that the clinical use of laninamivir has caused viral resistance in the currently epidemic viruses.

Clinical outcome of laninamivir octanoate hydrate for influenza in the 2013-2014 Japanese season

The clinical outcome of laninamivir octanoate hydrate (laninamivir) in the Japanese 2013-2014 influenza season was investigated. A total of 235 patients were enrolled, of whom 222 were evaluated for the duration of fever and other symptoms. The types/subtypes were 101 A(H1N1)pdm09 (45.5%), 37 A(H3N2) (16.7%), and 84 B (37.8%). The median durations of fever were 32.0, 41.0, and 50.0 h, and the median durations of symptoms were 74.5, 85.0, and 95.0 h for A(H1N1)pdm09, A(H3N2), and B, respectively. The differences among the three groups were not statistically significant. There was no significant difference in the duration of fever or symptoms between patients under 10 and 10 years or over. The median durations of fever were 46.0 and 58.0 h and the median durations of symptoms were 95.0 and 77.0 h for the Yamagata and Victoria lineages, respectively. The virus positive rates at day 5 were significantly different at 31.5% (28/89), 12.1% (4/33), and 34.7% (26/75) for the three type/subtypes, respectively. The virus positive rates for A(H1N1)pdm09 and B were significantly higher for the patients under 10 years than for the patients 10 years or older. (p = 0.0379 and 0.0320, respectively). No significant increase was found between the IC(50) of days 1 and 5. No adverse drug reactions associated with laninamivir were reported. These results indicate the continuing clinical utility of laninamivir against influenza, irrespective of the virus type/subtype or lineage, and that it is unlikely that the clinical use of laninamivir will lead to selection of resistant virus.

Continued effectiveness of laninamivir octanate hydrate for influenza treatment in Japan: comparison between the 2011-2012 and 2012-2013 influenza seasons

The clinical effectiveness of Laninamivir octanoate hydrate (laninamivir) was investigated in the Japanese 2012-2013 influenza season for comparison with that of the Japanese 2011-2012 influenza season. A total of 235 patients were enrolled, of whom 210 were evaluated for the duration of fever and other symptoms. The median durations of fever for A(H3N2) were 32.0 and 38.0 h and the median durations of symptoms for the A(H3N2) were 102.0 and 84.0 h for patients aged under 10 and 10 years or older, respectively. All four influenza B patients were 10 years or older, and their median duration of fever was 43.0 h and the median duration of symptoms was 71.0 h. There was no significant difference in the duration of fever or symptoms between the two seasons. The rates of patients A(H3N2) virus positive at day 5 were 37.2% (16/43) and 12.8% (18/141) for those aged under 10 years and 10 years or older, respectively. The virus positive rate was significantly higher for the patients under 10 years than for the patients aged 10 years or older (p < 0.0001). No significant change in IC50 value was found between days 1 and 5. Adverse drug reactions were reported by 2 of the 231 patients (0.87%), but neither was serious. These results suggest that laninamivir continued to be effective against influenza A(H3N2) with no safety issues and that it is unlikely that the clinical use of laninamivir will lead to virus resistance.

In vitro neuraminidase inhibitory activity of four neuraminidase inhibitors against clinical isolates of the influenza virus circulating in the Japanese 2013-2014 season

To assess the extent of viral resistance, we measured the 50% inhibitory concentration (IC50) of neuraminidase inhibitors (NAIs) for the influenza virus isolates in the 2013-2014 influenza season and compared the results to those of the 2010-2011 to 2012-2013 influenza seasons. Viral isolation was done with specimens obtained prior to treatment, and the type and subtype of influenza was determined by RT-PCR using type- and subtype-specific primers. The IC50 was determined by a neuraminidase inhibition assay using a fluorescent substrate. A total of 327 influenza viruses were isolated: 172 influenza A(H1N1)pdm09 (52.6%), 49 A(H3N2) (15.0%), and 106 B (32.4%). Numbers of Victoria and Yamagata lineage isolates were 36 and 70, respectively. Two A(H1N1)pdm09 isolates showed a high IC50 for oseltamivir (130 and 150 nM) exceeding by 100 times the geometric mean of the IC50 of oseltamivir for A(H1N1)pdm09 isolates (0.76 nM). No isolate showed a very high IC50 for A(H3N2) or B. The IC50 of the NAIs except for oseltamivir for A(H1N1) pdm09 were significantly higher than those of the 2010-2011 season (P < 0.05). The IC50 of all four NAIs for A(H3N2) were significantly lower than those of the 2012-2013 season (P < 0.001). The IC50 of the NAIs for B except for oseltamivir were significantly lower than those of the 2012-2013 season (P < 0.001). Although there are some isolates that show highly reduced sensitivity to oseltamivir among A(H1N1)pdm09 isolates, the currently epidemic influenza A(H1N1)pdm09, A(H3N2) and B viruses are susceptible to all four NAIs with no trend toward decreased sensitivity.

In vitro neuraminidase inhibitory activity of four neuraminidase inhibitors against clinical isolates of influenza virus in the Japanese 2012-2013 season

The neuraminidase inhibitors (NAIs) oseltamivir phosphate (Tamiflu(®)), zanamivir (Relenza(®)), laninamivir octanoate (Inavir(®)), and peramivir (Rapiacta(®)) have been available for the treatment of influenza in Japan since 2010. The emergence of resistant virus to any of the NAIs is a great concern for influenza treatment. To assess the extent of viral resistance, we measured the 50% inhibitory concentration (IC50) of each NAI for influenza virus isolates in the 2012-2013 influenza season and compared the results to those of the 2010-2011 and 2011-2012 influenza seasons. Viral isolation of specimens obtained prior to treatment was done using Madine-Darby canine kidney cells, and the type and subtype of influenza, A(H1N1)pdm09, A(H3N2), or influenza B, was determined by RT-PCR using type- and subtype-specific primers. The IC50 was determined by a neuraminidase inhibition assay using a fluorescent substrate. A total of 329 influenza viruses were isolated:5 influenza A(H1N1)pdm09 (1.5%), 316 influenza A(H3N2) (96.1%), and 8 influenza B (2.4%). No isolate showed an IC50 value exceeding 50 nM for any of the neuraminidase inhibitors. The IC50 values for A(H3N2) and B were similar to those of the 2010-2011 and 2011-2012 seasons. No isolate showed an increased IC50 value for A(H1N1)pdm09. These results indicate that the currently epidemic influenza viruses are susceptible to all four neuraminidase inhibitors, with no trend for IC50 values to increase at present.

[Comparison of the kinetics of granulocytes and lymphocytes between influenza A/H1N1/pdm09 and seasonal influenza A]

Peripheral blood tests are performed for the differentiation of febrile diseases, and are useful for diagnosing and determining the effectiveness of treatment in bacterial infections. However, their use for viral infections has not been well-investigated, nor do any clear views exist regarding their use with viral infections. We retrospectively investigated the results of routine peripheral blood tests for febrile diseases (differential leukocyte count and C-reactive protein (CRP)) performed in 1162 patients between the 2004/05 and 2009/10 influenza seasons, and identified the characteristic findings of influenza, along with the differences between cases of seasonal influenza A (including H3N2 and H1N1; hereafter, seasonal A; n = 614) and pandemic influenza (H1N1) 2009 seen during the 2009/10 influenza season (hereafter, A/H1N1/pdm09; n=548). The differential leukocyte count varies with age; therefore, analysis was performed by adjusting for the age of all patients using a generalized additive model (GAM). Increased granulocytes and decreased lymphocytes were confirmed during the initial stage of influenza infection, followed by inversion to decreased granulocytes and increased lymphocytes. The granulocyte count was significantly lower in A/H1N1/pdm09 compared to seasonal A, with levels 0.93- and 0.82-fold relative to seasonal A before and after treatment, respectively. The lymphocyte count was 1.12- to 1.30-fold greater in A/H1N1/pdm09 compared to seasonal A both before and after treatment, indicating significantly higher levels in A/H1N1/pdm09. CRP levels peaked 24-36 h after onset, with peaks of 0.88mg/dL for A/H1N1/pdm09 and 1.53 mg/dL for seasonal A. Peripheral blood counts change due to factors such as the time course of the disease, onset of complications, modification resulting from treatment, and side effects of pharmacotherapies. We report the present findings because we consider an understanding of the changes and kinetics of differential leukocyte counts in peripheral blood inherent to influenza to be important for diagnosis (particularly for the decision of doing rapid diagnosis test) and to promote recognition of the onset of complications and side effects during the course.

In vitro neuraminidase inhibitory activity of four neuraminidase inhibitors against influenza virus isolates in the 2011-2012 season in Japan

The neuraminidase inhibitors oseltamivir phosphate (Tamiflu®), zanamivir (Relenza®), laninamivir octanoate (Inavir®), and peramivir (Rapiacta®) have been available for the treatment of influenza in Japan since 2010. To assess the extent of viral resistance, we measured the 50% inhibitory concentration (IC₅₀) of each drug for influenza virus isolates from the 2011-2012 influenza season. Specimens were obtained from patients prior to treatment. Viral isolation was done using Madine-Darby canine kidney cells, and the type and subtype of influenza A(H1N1)pdm09, A(H3N2), or influenza B were determined by RT-PCR using type- and subtype-specific primers. The IC₅₀ was determined by a neuraminidase inhibition assay using a fluorescent substrate. The lineage of influenza B virus was determined by direct sequencing of the hemagglutinin gene. Influenza A(H3N2) and influenza B viruses were isolated in 283 and 42 patients, respectively, while no influenza A(H1N1)pdm09 virus was isolated. No isolate showed an IC₅₀ value exceeding 50 nM for any of the neuraminidase inhibitors. IC50 values for A(H3N2) were similar between the 2010-2011 and 2011-2012 seasons. In contrast, the IC₅₀ values for influenza B viruses in the 2011-2012 season to the four drugs were significantly lower than those found in the 2010-2011 season. These results indicate that the currently epidemic influenza viruses are susceptible to all four neuraminidase inhibitors, with no trend for IC₅₀ values to increase in Japan at present.

The duration of fever and other symptoms after the initiation of laninamivir octanoate hydrate in the Japanese 2011-2012 influenza season

Laninamivir octanoate hydrate (laninamivir) is a long-acting, single inhalation neuraminidase inhibitor that was approved in Japan in 2010 for the treatment of influenza A and B virus infection. We investigated the duration of fever and other symptoms after the initiation of laninamivir in the Japanese 2011-2012 influenza season. Virus isolation was done and the 50% inhibitory concentration (IC₅₀) was measured for the virus isolates at days 1 and 5. For 211 patients (A(H3N2): 190, B: 21), the median durations of fever of A(H3N2) and B patients were 33.0 and 50.0 h, respectively (p = 0.0989). Fever was resolved within 72 h after inhalation by 89.7% of the A(H3N2) patients and by 81.0% of the patients with B. The median durations of symptoms for A(H3N2) and B patients were 89.0 and 94.0 h, respectively (p = 0.5809). On day 5, the influenza virus-positive rates for A(H3N2) and B patients were significantly different: 25.8% (40/155) and 70.6% (12/17), respectively (p < 0.0001). No significant change in IC₅₀ value was found between day 1 and day 5 for any of the four tested neuraminidase inhibitors, and no IC₅₀ value exceeded 50 nM. The incidence of adverse drug reactions was 1.3% (3/234), with no serious reactions reported. These results show that laninamivir was effective for the treatment of both influenza A(H3N2) and B in this study, with no safety issues. The clinical effectiveness of laninamivir for A(H3N2) was superior to that for B.

Increased symptom severity but unchanged neuraminidase inhibitor effectiveness for A(H1N1)pdm09 in the 2010-2011 season: comparison with the previous season and with seasonal A(H3N2) and B

BACKGROUND

No studies of the clinical symptoms before starting therapy or of the effectiveness of neuraminidase inhibitors (NAIs) have been carried out of the 2009-2010 and 2010-2011 seasons that compare A(H1N1)pdm09 or the three circulating types of influenza virus.

METHODS

The clinical symptoms and duration of fever (body temperature ≥37·5°C) after the first dose of an NAI (oseltamivir, zanamivir, laninamivir) were analyzed. PCR was carried out for 365 patients with A(H1N1)pdm09 in the 2009-2010 season and for 388 patients with one of the three types of influenza circulating in the 2010-2011 season. IC50 for the three NAIs was also analyzed in 51 patients in the 2010-2011 season.

RESULTS

The peak body temperature was significantly higher in 2010-2011 than in 2009-2010 for patients under 20 years with A(H1N1)pdm09, and in the 2010-2011 season for children 15 years or younger with A(H1N1)pdm09 than for those with other virus types. The percentage of A(H1N1)pdm09 patients with loss of appetite or fatigue was significantly higher in 2010-2011 than in the previous season. The duration of fever was not affected by the kind of NAI or by age in multiple regression analysis. The percentage of patients afebrile at 48 hours after the first dose of NAI was significantly higher for A(H1N1)pdm09 than for A(H3N2) (laninamivir) or B (oseltamivir and laninamivir).

CONCLUSION

Although the clinical symptoms of A(H1N1)pdm09 were slightly more severe in the 2010-2011 season, the effectiveness of the NAIs remained high in comparison with 2009-2010 and with other types of seasonal influenza.

The post-infection outcomes of influenza and acute respiratory infection in patients above 50 years of age in Japan: an observational study

Please cite this paper as: Ikematsu et al. (2011) The post‐infection outcomes of influenza and acute respiratory infection in patients above 50 years of age in Japan: an observational study. Influenza and Other Respiratory Viruses 6(3), 211–217.

Objectives  Influenza can be a serious illness, especially for older people, and reducing the impact of influenza in elderly is important. The objective of this study was to estimate the prevalence and postinfection outcomes of influenza among the over‐50 population in Japan.

Design  An observational study was designed to ascertain the proportion of influenza cases in a population aged ≥50 years with acute respiratory infection (ARI) and to determine the postinfection outcomes of their illness during the 2008–09 influenza season in Japan. Respiratory specimens obtained from a total of 401 patients were tested by PCR for influenza viruses, respiratory syncytial virus (RSV) and human metapneumovirus (hMPV). The effectiveness of the seasonal trivalent influenza vaccine was estimated by a test‐negative case control analysis.

Setting  Seventeen outpatient clinics located in four separate areas of Japan.

Sample  Respiratory swab specimens from the ARI patients aged ≥50 years.

Main outcome measures  Laboratory confirmed influenza in patients presenting with ARI.

Results  In all, 89 (22.2%) of the patients were positive for one of the tested viruses; 70 (78.7%) with influenza, 17 (19.1%) with RSV, and 2 (2.2%) with hMPV. Cough (95.7% vs 73.4%), loss of appetite (67.1% vs 35.5%), absence from work (50.0% vs 23.0%), impact on daily activity (90.0% vs 62.5%), and caregiver absence from work (5.7% vs 0.6%) were observed higher in influenza patients. The duration of feeling weakness (6.3 ± 5.4 vs 3.6 ± 1.9 days) and average days of reduced activity (5.2 vs 3.6 days) were longer for influenza patients. Vaccine effectiveness was estimated to be 32.1% (95% CI: −14.9, 59.9%).

Conclusions  Influenza was the dominant ARI‐causing virus and the clinical and socio‐economic outcomes imposed on patients over 50 years of age was high for influenza.

Clinical effectiveness of oseltamivir and zanamivir for treatment of influenza A virus subtype H1N1 with the H274Y mutation: a Japanese, multicenter study of the 2007-2008 and 2008-2009 influenza seasons

BACKGROUND

Influenza A virus subtype H1N1 with the H274Y mutation emerged and spread worldwide. However, the clinical effectiveness of the neuraminidase inhibitors, oseltamivir and zanamivir, has not been adequately reevaluated.

METHODS

Data from 164 patients with H1N1 virus infection and 59 patients with H3N2 virus infection during the 2008-2009 influenza season and 68 patients with H1N1 virus infection during the 2007-2008 influenza season who received a neuraminidase inhibitor were analyzed. The duration of fever (body temperature 37.5 degrees C) after the first dose of oseltamivir or zanamivir and from onset of symptoms was calculated from patient reports. The influenza virus was isolated, and its subtype was determined by hemagglutinin inhibition assay and polymerase chain reaction. The H274Y neuraminidase mutation status was determined by sequencing the neuraminidase segment.

RESULTS

Of 68 patients with H1N1 virus infection during the 2007-2008 season, 41 were treated with oseltamivir, and 27 were treated with zanamivir. During the 2008-2009 season, 77 patients with H1N1 virus infection were treated with oseltamivir, and 87 were treated with zanamivir; 31 and 28 patients with H3N2 virus infection were treated with oseltamivir and zanamivir, respectively. All 49 analyzed H1N1 virus isolates obtained during the 2008-2009 season, but none of the isolates obtained during the 2007-2008 season, contained the H274Y mutation. The mean +/- standard deviation duration of fever after the start of oseltamivir therapy was significantly longer for patients with H1N1 virus infection (49.1+/-30.2 h) than it was for patients with H3N2 virus infection (33.7+/-20.1 h; P < .01) during the 2008-2009 season and patients with H1N1 virus infection during the 2007-2008 season (32.0+/-18.9 h; P < .001). The duration of fever was significantly longer after the first dose of oseltamivir than it was after the first dose of zanamivir for patients with H1N1 virus infection during the 2008-2009 season (P <.001). The duration of fever from onset of H1N1 virus infection was significantly longer for children 15 years of age during 2008-2009 (70.6+/-34.5 h) than it was for such children during 2007-2008 (48.4+/-21.2).

CONCLUSION

The effectiveness of oseltamivir, but not that of zanamivir, decreased significantly for H1N1 virus infection during the 2008-2009 season.

Clinical effectiveness of oseltamivir for influenza A(H1N1) virus with H274Y neuraminidase mutation

OBJECTIVE

To evaluate the clinical effectiveness of oseltamivir therapy started within 48h of the onset for influenza A(H1N1) virus with H274Y neuraminidase (NA) mutation.

METHODS

Virus was isolated before and four to six days after starting oseltamivir treatment from 73 outpatients with influenza A(H1N1) virus in the 2007-2008 and 2008-2009 seasons. NA inhibition assays (IC(50)) and sequence analyses were done using influenza viruses isolated from these patients. Body temperature was evaluated before and on the second, third, and fourth days after starting treatment.

RESULTS

H274Y mutation was not shown in the 2007-2008 season (44 patients) and shown in all 29 patients in the 2008-2009 season by NA sequence analyses. The mean IC(50) before oseltamivir treatment was significantly higher in 2008-2009 (319.3+/-185.4 nM) than in 2007-2008 (1.5+/-0.8 nM; p<.001). Patients < or =15 years with oseltamivir-resistant virus infection had a higher ratio of patients persisted virus after oseltamivir treatment than patients >15 years (50% and 11.8%, respectively, p=0.038), and a significant higher body temperature during oseltamivir treatment, compared to patients < or =15 years treated for oseltamivir-sensitive virus infection.

CONCLUSION

The clinical effectiveness of oseltamivir for the A(H1N1) virus was reduced in the 2008-2009 season compared with the previous season, especially in children, probably due to the H274Y mutation. Oseltamivir seems to be not recommended for children and patients with high-risk underlying diseases infected with H274Y mutated A(H1N1) virus.

[Detection of respiratory syncytial virus with nested RT-PCR and a new rapid detection test kit in patients with influenza-like illness, including elderly adults]

Respiratory syncytial virus (RSV) infection, a common lower respiratory infection in infants, is now recognized in the USA as a significant problem in elderly adults. RSV infection has rarely been reported in adults in Japan. Nasal samples from 77 patients with influenza-like illness (ILI) and negative for influenza in a rapid antigen detection kit were also tested by polymerase chain reaction (PCR) to identify RSV. A clinical trial was also conducted using a new antigen detection test kit for RSV based on immunochromatography. RSV was detected by nested RT-PCR in samples from nasal swabs of 10 patients--3 children and 5 adults--and nasal aspiration samples in 2 children. The frequency of RSV detection by nested RT-PCR in ILI patients with a negative response for influenza virus using the rapid detection kit was 27.3% (3/11) for children aged 0 to 1 year and 33.3% (2/6) for children aged 2-3 years. The frequency was 10% (1/10) for adults aged 30-39 years, 25% (1/4) for those aged 70-79 years, and 60% (3/5) for those aged 80-89 years. By month, the frequency was 25% (2/8) for December, 27.3% (6/22) for January, and 4.4% (2/45) for February. The main clinical symptoms of the 10 patients with RSV were: peak body temperature during the clinical course of 37.2-39.7 degrees C, cough, and rhinorrhea in 9. Stridor was observed in all five children, but not in the five adults. Clinical examination showed CRP to be 0.2-3.4 (mean 1.3) mg/dL and WBC to be 3070-8000 (mean 5584) /microL for nine patients. Lymphocytopenia was observed in the four adults from whom WBC fraction data was obtained. Chest X-ray was within normal limits. RSV was detected by the new rapid antigen detection kit in 9 of the 10 patients in whom RSV was detected by PCR, but not in any of the 67 patients in whom RSV was not detected. The diagnostic accuracy of the new antigen detection kit for RSV was thus excellent at 98.7% compared to PCR. RSV was detected from nasal swab specimens of a substantial number of elderly Japanese by PCR or the antigen detection kit.

A change in the effectiveness of amantadine for the treatment of influenza over the 2003-2004, 2004-2005, and 2005-2006 influenza seasons in Japan

A retrospective study of the 2003-2004, 2004-2005, and 2005-2006 influenza seasons was done to investigate the effectiveness of amantadine and oseltamivir for treating influenza A. Commercial antigen detection kits were used for diagnosis and data were collected from 44 clinics throughout Japan, using an Internet-based system. Oseltamivir was administered to 2775 patients and amantadine to 781 patients. The durations of fever, from the time of the first drug administration and from the onset of fever, were calculated for each patient. In the 2005-2006 season, the duration of fever from the first drug administration was longer for patients who received amantadine than for those who received oseltamivir when the patients were grouped by the time from onset of fever to the start of treatment (P < 0.001 for groups administered at 0-12, 13-24, 25-36 h from the onset) and by patient age (P < 0.001 for under 16 years and P < 0.05 for 16-64 years). Mean values of duration of fever from the first drug administration were 31.3 h, 31.3 h, and 31.9 h for oseltamivir therapy, and 33.3 h, 42.7 h, and 53.3 h for amantadine therapy, in the 2003-2004, 2004-2005, and 2005-2006 seasons, respectively. Reduction in the effectiveness of amantadine over the three influenza seasons were also observed in each age group of 0-6, 7-15, and 16-64 years. The studied season was an independent factor associated with the effectiveness of amantadine by multiple regression analysis. In conclusion, the effectiveness of oseltamivir did not change, but the effectiveness of amantadine was progressively reduced over the three influenza seasons.

A comparison of the effectiveness of zanamivir and oseltamivir for the treatment of influenza A and B

OBJECTIVE

To compare the effectiveness of zanamivir with oseltamivir for influenza A and B.

METHODS

1113 patients with influenza A or B were enrolled in the 2006-2007 influenza season. The duration of fever (temperature, >or=37.5 degrees C) and the percentage of patients afebrile at 24 and 48 h after the first dose of zanamivir or oseltamivir were calculated. Virus persistence after zanamivir therapy was also evaluated.

RESULTS

There were marginally significant differences between the duration of fever after the first dose of zanamivir (31.8+/-18.4h) and oseltamivir (35.5+/-23.9h) for influenza A (p<0.05). The duration of fever after starting zanamivir therapy (35.8+/-22.4h) was significantly shorter than that of oseltamivir (52.7+/-31.3h) for influenza B (p<0.001). There were no significant differences between influenza A and B in the percentage of patients afebrile at 24 or 48 h after the first inhalation of zanamivir. The reisolation rate after zanamivir therapy showed marginally significant differences between influenza A and B (<0.05). By multiple regression analysis, therapy (zanamivir or oseltamivir) was the major determinant affecting the duration of fever for influenza B.

CONCLUSION

Zanamivir therapy is more effective than oseltamivir for the treatment of influenza B infection.

A comparison of the effectiveness of oseltamivir for the treatment of influenza A and influenza B: a Japanese multicenter study of the 2003-2004 and 2004-2005 influenza seasons

BACKGROUND

To compare the effectiveness of oseltamivir for treatment of influenza A and influenza B, we conducted a prospective, multicenter study of the 2003-2004 and 2004-2005 influenza seasons. The study included 3351 patients in whom influenza had been diagnosed by use of an antigen detection test kit.

METHODS

Oseltamivir was administered to 1818 patients with influenza A and 1485 patients with influenza B. No anti-influenza drugs were administered to 21 patients with influenza A or to 27 patients with influenza B. Patients receiving oseltamivir therapy were divided into 4 groups according to the time between the onset of fever (temperature, > or = 37.5 degrees C) and administration of the first dose of oseltamivir (0-12 h, 13-24 h, 25-36 h, and 37-48 h). The patients were also divided into 4 subgroups on the basis of age (0-6 years, 7-15 years, 16-64 years, and >64 years). Virus isolation was performed after completion of oseltamivir therapy for 44 patients with influenza A and 31 patients with influenza B.

RESULTS

The duration of fever was significantly shorter for patients with influenza A and B who were treated with oseltamivir than for patients who were not treated with an anti-influenza drug (P<.001 for both). The time until the patient became afebrile after the initial administration of oseltamivir and the duration of fever were significantly longer for patients with influenza B than for patients with influenza A for the 0-12 h, 13-24 h, 25-36 h, and 37-48 h groups (P<.001) and for all age groups (P<.001). After 4-6 days of oseltamivir therapy, the influenza B virus reisolation rate (51.6%) was significantly higher than the influenza A virus reisolation rate (15.9%) (P<.001).

CONCLUSION

Oseltamivir is less effective for influenza B than for influenza A with regard to duration of fever and virus persistence, irrespective of patient age or the timing of administration of the first dose.

Factors influencing the effectiveness of oseltamivir and amantadine for the treatment of influenza: a multicenter study from Japan of the 2002-2003 influenza season

BACKGROUND

To evaluate the effectiveness of oseltamivir and amantadine for the treatment of influenza with respect to various clinical factors, a prospective multicenter study of the influenza season of 2002-2003 was done with 2163 patients whose condition was diagnosed by an antigen-detection test kit.

METHODS

Oseltamivir was administered to 803 patients with influenza A (A+Os group) and 684 patients with influenza B (B+Os group). Amantadine was administered to 676 patients with influenza A (A+Am group).

RESULTS

For each group, the duration of fever (i.e., body temperature, > or = 37.5 degrees C) was significantly shorter in patients who received the drug within 12 h after the onset of symptoms than in patients who received the drug > 12 h after the onset. For all 3 groups, the duration of fever was shorter in patients with a highest temperature < 39 degrees C than in patients with temperatures > or = 39 degrees C. The duration of fever was significantly longer for the B+Os group than for the A+Os group. Multiple regression analysis found that the type of influenza, the highest body temperature, and the time between the onset of symptoms and the start of treatment are independent factor that influence the duration of fever.

CONCLUSIONS

Early administration increases the benefit of anti-influenza drugs--not only the benefit of oseltamivir treatment for influenza A, but also the benefit of amantadine treatment for influenza A and oseltamivir treatment for influenza B. Oseltamivir may be less effective as a treatment for influenza B than for influenza A. A highest body temperature of > or = 39 degrees C was an indicator of a longer duration of fever.

Clinical Symptoms of Influenza Infection in the 2002-2003 Season

The highest body temperature and clinical symptoms during the influenza infection were analyzed on 2,145 patients with influenza, (type A: 1,408cases, type B: 737cases: confirmed by a rapid diagnosis kit, Capilia FluA, B), and for 670 patients with a negative response to the rapid diagnosis kit (controls). The study was a multi-center study of the 2002-2003 influenza season. The percentages of patients with fever over 38 degrees C, 38.5 degrees C and 39 degrees C were significantly higher in influenza A than in influenza B or controls (16-64 yrs). Over 80% of the patients in all age groups of 0-6 yrs, 7-15 yrs, 16-64 yrs or over 64 yrs with influenza A or B had a cough. The percentage of patients with cough was significantly higher for patients with influenza A or B than for controls under 65 yrs. The percentages of influenza A or B patients with rhinorrhea or loss of appetite were significantly higher than in controls under 65 yrs. The percentage of patients reporting fatigue, headache or myalgia was significantly higher for influenza A than for controls of 16-64 yrs. Differences in symptoms, including fever, were minimal between influenza A and B patients under 16 yrs, and also among influenza A, B and controls in patients over 64 yrs. The percentage of patients with cough was not different among the three age groups by influenza A or B. However, the percentage of patients with rhinorrhea, loss of appetite, vomiting or diarrhea was higher in children under 16 yrs than in adults aged 16-64 yrs in influenza A or B. In conclusion, consideration must be given to the patient's age and the type of influenza when doing a symptomatic diagnosis of influenza. In addition, the use of a rapid diagnosis kit seems necessary for the diagnosis of influenza in elderly patients, who may have no specific symptoms of influenza.

An Analysis of the 2002-2003 Influenza Epidemic Focusing on Patients Infected with Types A and B in the Same Season Sequentially

A total of 2,320 cases of influenza A (1,517 cases) and B (803 cases) in the 2002-2003 influenza season were analyzed. Influenza infection was confirmed by a rapid diagnosis kit, based on the immunochromatography method, at 24 clinics in 18 of the 47 prefectures of Japan. Influenza A/H3N2 was reported between November 22 and April 12 (the median at January 21), and influenza B was reported between December 24 and April 20 (the median at February 16). The mean age of type B patients (16.7 years old) was significantly younger than that of type A patients (26.7 years old) (p < 0.001). Pneumonia was more frequently a complication of type A (0.63%) than of type B (0%, p < 0.05). Although 5 type A patients needed hospitalization, neither hospitalization nor death was associated with type B. Of the 2,293 cases, 27 (1.2%) were infected with both influenza of A and B. The age of these 27 patients ranged from 2 to 51 years (mean of 11.2 years), but 20 of the 27 patients were 9 years of age or under. Type B followed type A in 25 patients. The median date of these 25 type A patients was January 22, similar to that of all cases of type A, January 21. However, the median date of type B infection was March 3, 15 days later than that of all patients with type B, February 16. The mean age of the 27 cases was significantly younger than that of all cases of type A (p < 0.001) and type B (p < 0.05). In epidemics consisting of multiple types of influenza viruses, patients may be infected by more than one virus. This is especially true for children.

A prospective, Internet-based study of the effectiveness and safety of influenza vaccination in the 2001–2002 influenza season

The effectiveness of the influenza vaccine used in the 2001-2002 influenza season in Japan was investigated in a large-scale, geographically widely distributed, Internet-based study. Data were collected from 8841 of 9902 subjects registered by 38 clinics prior to the start of influenza season. Subjects were categorized into three groups by vaccination regimen: unvaccinated, vaccinated once, and vaccinated twice. Efficacy was also analyzed for three age groups: 0-15, 16-64, and 65-104 years. Influenza-like illness (ILI) was diagnosed according to Ministry of Health (MWH, Labor and Welfare in Japan) criteria. Laboratory-confirmed influenza cases were analyzed separately. The respective vaccine efficacy in the 0-15 years group for the one- and two-dose regimens was 67.6 and 84.5% for ILI and 54.0 and 79.8% for laboratory-confirmed influenza. Influenza vaccination was also shown to be effective in subjects 16-64 years. Vaccine effectiveness was not able to be determined for the over 65 years group, probably due to an insufficient number of infected patients. These results suggest that influenza vaccination is effective for children and adults and that a two-dose regimen is superior to a single dose in children 0-15 years.

[Effectiveness of oseltamivir on influenza and influencing factors: age of patients, type of influenza virus and timing of initial administration]

A multi-center open study using the internet was performed during the influenza season of 2001-2002 to evaluate the effectiveness of the anti-influenza agent, oseltamivir, on influenza in relation to: (1) age of patients; (2) type of influenza virus; and (3) timing of initial administration after the onset of the first symptoms of influenza. The study comprised of 779 cases of influenza confirmed by rapid detection tests from 44 clinics in Japan. Patients consisted of 4 age groups, 0-6, 7-15, 16-64 and 65-85 years. All patients were administered oseltamivir within 24 hours, at 25-48 or after 48 hours from the onset of the first symptoms of influenza. Data collected from each age group were the highest body temperature and duration of fever (> or = 37.5 degrees C). The percentage of afebrile patients was calculated at 24, 48 and 72 hours after the initial administration; data were also evaluated by the type of influenza virus A and B. The highest body temperature was higher with statistical significance as patients' age decreased. The duration of febrile period (days) was significantly longer in 0-6 years (2.57 +/- 0.95) than in 65-85 years (2.18 +/- 0.93). Evaluation of the percentage of afebrile patients revealed: the percentage at 24 hours was significantly lower in 0-6 years (28.4%) than in 16-64 years (44.0%); the percentage at 48 and 72 hours showed similar results in each age group; the percentage at 48 and 72 hours was significantly higher when administered initially within 24 hours than over 48 hours after the onset of the first symptoms of influenza; the percentage at 24 and 48 hours was significantly higher when administered within 24 hours than at 25-48 hours; and the type of influenza virus did not affect the percentage. In conclusion, effectiveness of oseltamivir seemed to be affected to an extent by the patients' age and little by the type of influenza virus. Oseltamivir was more effective when administered as early as possible after the onset of the symptoms of influenza.

[A study on the response selection and inhibition in a cognitive conflict task using event-related potentials]

This study examined the hypothesis (Eriksen & Schultz, 1979) that a subject checks whether a prepared response is correct or not in the Eriksen and Eriksen (1974) cognitive conflict task, using event-related potentials (ERPs). Fourteen right-handed subjects were required to respond selectively to a central target letter flanked with compatible (e.g., HHHHHHH) or incompatible (e.g., SSSHSSS) noise letters, or not to respond to asterisks (*******). The results showed that the lateralized readiness potential indicating an incorrect preparation and the NO-GO potential reflecting a response inhibition emerged for incompatible stimuli. These findings indicate that a prepared response was recognized as erroneous, and was inhibited. Therefore, it is suggested that the check operation functioned in the cognitive conflict task. Furthermore, the result that the NO-GO potential latency for incompatible stimuli was longer than that for NO-GO stimuli suggests that the timing of NO-GO decision and response inhibition by the check operation influenced the NO-GO potential latency.

Effects of proglumide on cholecystokinin-8-induced exocrine and endocrine pancreatic responses in conscious sheep

The effects of cholecystokinin (CCK)-8, either alone or together with the CCK antagonist, proglumide on both exocrine and endocrine pancreatic responses were examined in conscious sheep. Intravenous infusions of CCK-8 (120 pmol/kg/min for 40 min) with vehicle (0 mumol/kg/min proglumide) significantly increased both amylase output in pancreatic juice and plasma insulin concentrations (P < 0.05). Concomitant infusions of proglumide (5-40 mumol/kg/min for 50 min) inhibited both amylase and insulin secretory responses induced by CCK-8 infusion. The antagonistic effects of proglumide occurred in a dose-dependent manner, and proglumide infusion at dose of 20 mumol/kg/min or above simultaneously inhibited CCK-8-induced amylase and insulin responses. In conclusion, although the type of receptor involved is not characterized at present, exogenously infused CCK-8 acts on B cells via a CCK-receptor-mediated mechanism and induces insulin secretion in sheep.

[A study of information processing of cognitive conflict using event-related potentials]

This study examined whether cognitive conflict, reported by Eriksen and Eriksen (1974), could be explained by a model of reciprocal inhibition between correct and incorrect response preparation. Subjects responded selectively to a central target letter with flanking compatible (e.g., HHHHH) or incompatible (e.g., SSHSS) noise letters. In the mixed condition all four stimuli were mixed randomly in a block, and in the blocked condition only two stimuli with identical noises were used. The results showed that the reaction times to incompatible stimuli were delayed in the mixed condition compared with that to compatible stimuli, while the delay was significantly reduced in the blocked condition. This blocking effect was also shown on P3 latencies, an event-related potential measure of stimulus evaluation, but not on lateralized readiness potentials (LRPs), a measure of response preparation. Furthermore, irrespective of blocked/mixed conditions, LRPs indicating incorrect preparation were observed. These findings suggest that cognitive conflict could not be explained by the reciprocal inhibition model based on response preparation, but by a model based on stimulus evaluation.

Effects of intravenous infusions of cholecystokinin (CCK)-8 on exocrine and endocrine pancreatic secretion in conscious sheep

The effects of cholecystokinin (CCK)-8 on both exocrine and endocrine pancreatic functions were examined simultaneously in five conscious sheep. Intravenous infusions of CCK-8 (0, 5, 10, 20, 30, 60, 120 and 240 pmol/kg/min for 40 min) induced dose-dependent increases in flow rate, and in protein and amylase outputs in pancreatic juice. The same CCK-8 infusions induced dose-dependent increases in plasma insulin, but no change in plasma glucagon concentrations. The threshold dose (10-30 pmol/kg/min) of CCK-8 infusion for stimulating insulin secretion was similar to that for stimulating amylase output. In conclusion, using amylase output as an indicator of physiological action, CCK is one of the potential candidates as a physiological regulator of insulin, but not glucagon secretion in sheep.

Effects of intravenous infusions of cholecystokinin-8 and pentagastrin on plasma concentrations of insulin and glucagon in sheep

The effects of cholecystokinin-8 (CCK-8) and pentagastrin on insulin and glucagon secretion were studied in conscious sheep. Intravenous infusions of CCK-8 (3 to 1000 pmol kg-1 min-1 for 30 minutes) induced a dose-dependent increase in plasma insulin, but did not alter plasma glucagon concentration. The threshold dose of CCK-8 for stimulation of insulin secretion was 10 to 30 pmol kg-1 min-1. Pentagastrin was infused intravenously at doses of 10 to 3000 pmol kg-1 min-1. The maximal dose of pentagastrin slightly stimulated insulin, but not glucagon, secretion. The insulin secretory activity of pentagastrin was only 1/300 that of CCK-8 on a molar basis. The threshold dose of CCK-8 for stimulation of insulin secretion was similar to that for exocrine pancreatic secretion obtained in earlier studies. In conclusion, CCK is a potential candidate as a physiological factor regulating insulin secretion in sheep.

Optical resolution of (+/-)-all-trans-3-hydroxyretinal by use of high-performance liquid chromatography

Racemic all-trans-3-hydroxyretinal (3-OH-RAL) (1) was converted by a reaction with (-)-camphanic acid chloride (CpCl) into a diastereomixture of camphanates (2a) and (2b) which was separated by preparative high-performance liquid chromatography (HPLC) to give two esters (2a) and (2b) in pure state, respectively. Saponification of (2a) and (2b) independently afforded optically active (3S)- and (3R)-3-OH-RALs (3a) and (3b), respectively, whose absolute structures were determined by circular dichroism (CD) spectra. Racemic 3-OH-RAL was separated to two peaks by HPLC using chiral column (ChiraSpher, Merck). Cochromatography with authentic specimens (3a) and (3b) showed that the peak with a short retention time corresponded to (3R)-isomer and the other to (3S).