Cellular and humoral immune responses to COVID-19 booster vaccination in Japanese dialysis patients.

BACKGROUND: Dialysis patients are susceptible to developing severe coronavirus disease 2019 (COVID-19) due to hypoimmunity. Antibody titers against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) after the primary vaccinations are lower in hemodialysis (HD) patients than in healthy individuals. This study aimed to evaluate the effect of a SARS-CoV-2 booster vaccination in HD and peritoneal dialysis (PD) patients based on antibody titers and cellular and humoral immunity. METHODS: Participants of the control, HD, and PD groups were recruited from 12 facilities. SARS-CoV-2 antigen-specific cytokine and IgG-antibody levels were measured. Regulatory T cells and memory B cells were counted using flow cytometry at 6 months after primary vaccination with BNT162b2 and 3 weeks after the booster vaccination in HD and PD patients and compared with those of a control group. RESULTS: Booster vaccination significantly enhanced the levels of antibodies, cytokines, and memory B cells in three groups. The HD group showed significantly higher levels of IgG-antibodies, IL-1ß, IL-2, IL-4, IL-17, and memory B cells than those in the control group at 3 weeks after the booster dose. The PD group tended to show similar trends to HD patients but had similar levels of IgG-antibodies, cytokines, and memory B cells to the control group. CONCLUSIONS: HD patients had significantly stronger cellular and humoral immune responses than the control 3 weeks after the booster dose. Our findings will help in developing better COVID-19 vaccination strategies for HD and PD patients.

Different immunological responses following immunization with two mRNA vaccines.

INTRODUCTION: Immunological responses were investigated following immunization with two mRNA vaccines: BNT162b2 and mRNA-1273. METHODS: Neutralizing antibody (NAb) was assayed before, 2-4 weeks after, and 3 and 6 months after the primary immunization, and the same time-points after booster dose with 6- or 8-months interval. Whole-blood culture was stimulated with spike antigen, and cytokine production was assayed. RESULTS: NAb was detected after primary immunization, NAb titers began to decrease three months after primary immunization with BNT162b2, lower than those after mRNA-1273, and elevated after booster immunization. The NAb level was 1/2 lower against δ variant, and 1/16 lower against omicron variant in comparison with that against α variant. Cytokine production following immunization with mRNA-1273 was maintained within three months at higher levels of Th1 (TNF-α), Th2 (IL-4 and IL-5), and inflammatory cytokines (IL-6 and IL-17) than that following immunization with BNT162b2, reflecting prominent levels of NAb following immunization with mRNA-1273. Cytokine production decreased six months after primary immunization in both vaccine recipients and was enhanced following booster doses. During the omicron outbreak, medical staff members in the outpatient office experienced asymptomatic infection, with a greater than 4-fold increase in NAb titers against omicron variant even after booster immunization. Asymptomatic infection enhanced the production of Th2 and inflammatory cytokines. CONCLUSION: mRNA-1273 induced stronger NAb responses with wide-range cross-reactive antibodies against δ and omicron variants. mRNA-1273 induced higher levels of Th1, Th2, and inflammatory cytokines than BNT162b2 did, reflecting higher levels of NAb against variant strains.

COVID-19 vaccine induced interstitial lung disease.

A 60-year-old man presented with dyspnea four days after the second dose of the coronavirus disease (COVID-19) vaccine. Imaging revealed extensive ground-glass opacification. Blood tests were notable for elevated KL-6 levels. Bronchoalveolar lavage fluid analysis showed increased lymphocyte-dominant inflammatory cells and decreased CD4/CD8 ratio. These findings were consistent with the diagnosis of drug-induced interstitial lung disease (DIILD). To the best of our knowledge, this has never been reported in previous literature. Treatment with glucocorticoids relieved his symptoms. This paper highlights that although extremely rare, COVID-19 vaccine could cause DIILD, and early diagnosis and treatment are crucial to improve patient outcomes.

Effectiveness of four doses of pertussis vaccine during infancy diminished in elementary school age: A test-negative case-control study in Japan.

OBJECTIVE: The Japanese national immunization program recommends that children receive 4 doses of acellular pertussis vaccine between 3 months and 2 years of age. Nevertheless, the number of pertussis cases is increasing in elementary school children aged 6-12 years. Therefore, a test-negative case-control study was conducted to assess the effectiveness of the pertussis vaccine program. METHODS: Subjects included children aged ≥3 months who visited a collaborating hospital due to pertussis-specific cough between October 2017 and November 2019. All subjects underwent diagnostic tests for pertussis, and those diagnosed as positive were regarded as cases. Subjects diagnosed as pertussis-negative were classified as controls. Vaccination history was collected using a questionnaire administered to parents with reference to immunization records. Logistic regression models were employed to calculate the odds ratio (OR) and 95% confidence interval for laboratory-confirmed pertussis. RESULTS: Of 187 recruited subjects (120 cases and 67 controls), questionnaire responses were obtained for 145 subjects (95 cases and 50 controls). Compared with unvaccinated subjects, the vaccine effectiveness (VE) of 4 doses was 70% among all subjects and reached to 90% with marginal significance among subjects under 6 years of age. However, among school-aged subjects, the VE was not suggestive of protection against pertussis (VE: 8%). For vaccinees given 4 doses, the OR for developing pertussis increased significantly with longer duration since the fourth dose (compared with <4.5 years, OR of 6.0-8.2 years = 5.74; OR of ≥8.3 years = 3.88; P for trend by duration < 0.01). CONCLUSION: Effectiveness of administering 4 doses of pertussis vaccine during infancy decreases with time passed since the fourth dose. This regimen does not protect school-aged children against pertussis.

Trivalent inactivated influenza vaccine effective against influenza A(H3N2) variant viruses in children during the 2014/15 season, Japan.

The 2014/15 influenza season in Japan was characterised by predominant influenza A(H3N2) activity; 99% of influenza A viruses detected were A(H3N2). Subclade 3C.2a viruses were the major epidemic A(H3N2) viruses, and were genetically distinct from A/New York/39/2012(H3N2) of 2014/15 vaccine strain in Japan, which was classified as clade 3C.1. We assessed vaccine effectiveness (VE) of inactivated influenza vaccine (IIV) in children aged 6 months to 15 years by test-negative case-control design based on influenza rapid diagnostic test. Between November 2014 and March 2015, a total of 3,752 children were enrolled: 1,633 tested positive for influenza A and 42 for influenza B, and 2,077 tested negative. Adjusted VE was 38% (95% confidence intervals (CI): 28 to 46) against influenza virus infection overall, 37% (95% CI: 27 to 45) against influenza A, and 47% (95% CI: -2 to 73) against influenza B. However, IIV was not statistically significantly effective against influenza A in infants aged 6 to 11 months or adolescents aged 13 to 15 years. VE in preventing hospitalisation for influenza A infection was 55% (95% CI: 42 to 64). Trivalent IIV that included A/New York/39/2012(H3N2) was effective against drifted influenza A(H3N2) virus, although vaccine mismatch resulted in low VE.

Effectiveness of Trivalent Inactivated Influenza Vaccine in Children Estimated by a Test-Negative Case-Control Design Study Based on Influenza Rapid Diagnostic Test Results.

We assessed vaccine effectiveness (VE) against medically attended, laboratory-confirmed influenza in children 6 months to 15 years of age in 22 hospitals in Japan during the 2013-14 season. Our study was conducted according to a test-negative case-control design based on influenza rapid diagnostic test (IRDT) results. Outpatients who came to our clinics with a fever of 38 °C or over and had undergone an IRDT were enrolled in this study. Patients with positive IRDT results were recorded as cases, and patients with negative results were recorded as controls. Between November 2013 and March 2014, a total of 4727 pediatric patients (6 months to 15 years of age) were enrolled: 876 were positive for influenza A, 66 for A(H1N1)pdm09 and in the other 810 the subtype was unknown; 1405 were positive for influenza B; and 2445 were negative for influenza. Overall VE was 46% (95% confidence interval [CI], 39-52). Adjusted VE against influenza A, influenza A(H1N1)pdm09, and influenza B was 63% (95% CI, 56-69), 77% (95% CI, 59-87), and 26% (95% CI, 14-36), respectively. Influenza vaccine was not effective against either influenza A or influenza B in infants 6 to 11 months of age. Two doses of influenza vaccine provided better protection against influenza A infection than a single dose did. VE against hospitalization influenza A infection was 76%. Influenza vaccine was effective against influenza A, especially against influenza A(H1N1)pdm09, but was much less effective against influenza B.

Novel clinical features of recurrent human respiratory syncytial virus infections.

Children and elderly individuals are often infected easily and repeatedly with human respiratory syncytial virus (HRSV); however, the features of recurrent infection in the same individual are defined poorly. To clarify the clinical significance of repeated HRSV infections in relation to subgroup epidemiology, this study performed prospective and longitudinal analyses in children with lower respiratory tract infections over 20 consecutive epidemics between 1985 and 2005 at a pediatric outpatient clinic in Kawasaki, Japan. HRSV infections were confirmed by 2 types of reverse-transcription PCR. Samples obtained from patients with repeated infections were subjected to sequence analysis and cloning analysis. A total of 1,312 lower respiratory tract infections observed in 1,010 patients were diagnosed as HRSV infections. Repeated HRSV infections occurred in 208 of the 1,010 patients. Analysis of the patients with repeated infections revealed that children were often infected multiple times even within a single short epidemic. Some patients were re-infected with strains having the same or virtually identical N gene sequences. In patients infected more than 4 times, cloning analysis revealed more frequent dual infections with both subgroups (23.8%). The HRSV-A subgroup caused subsequent homologous infections more frequently than did HRSV-B; furthermore, HRSV-A infections provided no protection from a second homologous infection. In contrast, HRSV-B infections offered significant protection against a second homologous infection. Statistical analysis revealed alleviation of symptoms with a reduced rate of dyspnoeic attacks only in the group re-infected with homologous HRSV-A strains. Thus, this study elucidates new clinical features of recurrent HRSV infection.

A new method for the detection of neutralizing antibodies against mumps virus.

Neutralization test is the most reliable method of evaluating immunity against viral diseases but there is no standard procedure for mumps virus, with tests differing in the infectivity of the challenge virus, 50% plaque reduction or complete inhibition of cytopathic effects (CPE), and usage of complement. A reliable, easy, and simple neutralization test for mumps virus was developed in this study. A recombinant mumps virus expressing GFP was generated as a challenge virus. Complement was added to the neutralizing mixture at 1∶200 when stocked serum samples were used. Neutralizing antibody titers were expressed as the reciprocal of the highest dilution that did not exceed two-fold of FU values (GFP expression) of the cell control wells. A total of 1,452 serum samples were assayed by inhibition of GFP expression in comparison with those examined by conventional 100% inhibition of CPE. 1,367 (94.1%) showed similar neutralizing antibody titers when examined by both methods. The GFP expression inhibition assay, using a recombinant mumps virus expressing GFP, is a simple and time- saving method.

Effect of early measles vaccination (AIK-C strain) for preterm infants.

BACKGROUND: The level of maternal antibodies decreases more quickly in preterm than term infants, leaving them unprotected against measles. To protect premature infants from measles, an early vaccination trial was investigated. METHODS: Changes in the serum measles neutralization test (NT) antibody titer were examined in 152 infants (average gestational period, 29 weeks; average birthweight, 1203 g). RESULTS: The average antibody titer (2(n)) was 2(3.5) at birth and 2(2.2) at 1-3 months of age, and in all cases, NT antibody titer decreased to <1:4 (150 IU/mL). The AIK-C measles vaccine was given to 17 preterm infants at the age of 6 months, and induced sufficient serological responses without any serious adverse events. NT antibody level did not decay during 12 months after vaccination. CONCLUSION: Early immunization at 6 months of age is effective to protect preterm infants in the outbreak setting.

Modified adult measles in outbreaks in Japan, 2007-2008.

Different genotypes of C1, D3, D5, and H1 were isolated in outbreaks of 1984, 1987-1988, 1991-1993, and 2001, respectively, when the previous circulating genotype was replaced successively by a new genotype, through molecular studies of measles since 1984 in Japan. In March 2007, several patients with measles were observed in outpatient clinics, who were all young adolescents in high school and university students. The outbreak expanded subsequently throughout Japanese districts in May and is still ongoing in 2008. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) was used to detect the measles genome from 18 clinical samples obtained from patients suspected of modified measles infection with a very mild febrile illness. The measles genome was detected in nine patients by reverse transcription polymerase chain reaction (RT-PCR) and in 12 patients by RT-LAMP. Six measles strains were isolated in the 2007-2008 outbreak and identified as the D5 genotype (MVi/Bangkok.THA/93 type) different from the D5 sub-cluster (MVi/Palau.BLA/93 type) isolated in 1990-2005. Similar Bangkok type D5 strains were isolated in Phnom Penh in 2002 and in Taiwan in 2003, suggesting that the D5 strains might have been introduced via South East Asia, rather than resulting from the accumulation of mutations in the D5 strains of 1990-2005. One D9 strain was isolated from a sporadic case in Aichi in 2006. There was no difference in the antigenicity of the D9 and D5 strains in comparison with the vaccine strain. Infrastructure of systematic laboratory-based surveillance system should be established in order to confirm measles virus infection in Japan.

Oseltamivir-resistant influenza a viruses circulating in Japan.

Surveillance studies of the influenza viruses circulating in Europe and other countries in 2007 and 2008 have revealed rates of resistance to oseltamivir of up to 67% among H1N1 viruses. In the present study, we examined 202 clinical samples obtained from patients infected with H1N1 virus in Japan in 2007 and 2008 for oseltamivir resistance and found that three were oseltamivir resistant (1.5%). The 50% inhibitory concentrations (IC(50)s), as measured by a sialidase inhibition assay with these drug-resistant viruses, were >100-fold higher than those of the nonresistant viruses (median IC(50), 12.6 nmol/liter). The His274Tyr (strain N2 numbering) mutation of the neuraminidase protein, which is known to confer oseltamivir resistance, was detected in these three isolates. Phylogenetic analysis showed that one virus belonged to a lineage that is composed of drug-resistant viruses isolated in Europe and North America and that the other two viruses independently emerged in Japan. Continued surveillance studies are necessary to observe whether these viruses will persist.

Mumps virus reinfection is not a rare event confirmed by reverse transcription loop-mediated isothermal amplification.

Clinically apparent mumps reinfection is considered extremely rare, but several cases have been suspected of reinfection in an out-patient clinic. In this study, virological examination, virus isolation, the reverse transcription loop-mediated isothermal amplification (RT-LAMP), and IgG and IgM EIA antibodies, were examined in order to identify mumps reinfection. Patients were divided into three categories; the reinfection group comprised 29 patients with a history of natural infection, the vaccine-failure group consisted of 37 patients with an immunization history, and two patients had histories of both immunization and mumps infection. Another 25 patients were enrolled as a primary infection group. Mumps virus was isolated in 5 (17%) and the genome was detected in 12 (41%) of 29 in the reinfection group. Reinfection was confirmed in 21/28, demonstrating high avidity of IgG EIA. Mumps virus was isolated in 15 (41%) and there was a higher positivity of genome amplification in 25 (68%) of 37 patients in the vaccine-failure group. Among these, 23 were confirmed as secondary vaccine failure by high avidity IgG EIA serology. In the primary infection group, the isolation rate and genome detection rate was higher in 16 (64%) and in 18 (72%) of 25 patients, respectively. There was no significant difference in virus load among the three groups but high mumps virus load was suspected in the IgM EIA-positive group based on the shorter amplification time on RT-LAMP. Mumps virus reinfection was confirmed by RT-LAMP and an IgG avidity test and was not a rare event.

Development of a new neutralization test for measles virus.

Sero-epidemiological studies are required to identify populations susceptible to measles. The hemagglutination inhibition (HI) test is no longer sensitive enough to confirm immunity to measles, and at present the particle agglutination (PA) test and enzyme-linked immunosorbent assay (EIA) are employed. The most reliable method is the neutralization test (NT), but it is time-consuming and requires experience. To simplify the NT, a recombinant measles AIK-C virus expressing green fluorescence protein (GFP-MVAIK) was constructed and used as a challenge virus. Plaques and cytopathic effects were visualized under ultraviolet light and detected easily, and measuring the intensity of the fluorescence enabled a reduction in the time-consuming steps. Neutralizing antibody titers of a complete inhibition neutralization test were equivalent to those of a 90% plaque reduction neutralization test. Comparison of four methods, HI, PA, EIA and the complete inhibition neutralization test, showed that only the results of EIA correlated well with those of the complete inhibition neutralization test, but sera with borderline levels by EIA were sometimes negative by the complete inhibition neutralization assay.

Simple differentiation method of mumps Hoshino vaccine strain from wild strains by reverse transcription loop-mediated isothermal amplification (RT-LAMP).

Mumps virus is still circulating and annual mumps outbreaks occur with fluctuating magnitudes in Japan. Aseptic meningitis has been reported after vaccination and it would be of importance to determine whether this was related to the vaccination. The objective of this study was to develop a sensitive, specific and rapid diagnostic method for the differentiation of the Hoshino vaccine strain from circulating wild types. We developed a reverse transcription loop-mediated isothermal amplification (RT-LAMP) method of the hemagglutinin neuraminidase (HN) region for the detection of mumps virus genome from clinical samples. The typical ladder pattern disappeared after the LAMP products of the Hoshino vaccine strain were digested with ScaI, but those of wild types were not cut by ScaI. We obtained 19 cerebro spinal fluids (CSF) from the patients with aseptic meningitis and 17 salivary swab samples from the patients with acute parotitis after mumps vaccination, in which one case was complicated with orchitis. Mumps virus genome was detected in 18 CSF samples and in all NPS by RT-LAMP. The Hoshino vaccine strain was identified in 16 out of 18 CSF RT-LAMP positives and in 11 out of 17 NPS samples and the remaining samples were identified as wild types. RT-LAMP followed by ScaI digestion is a sensitive, simple and rapid differential method and useful for laboratory surveillance for vaccine-adverse events.

Current status of measles in Japan: molecular and seroepidemiological studies.

On account of the measles vaccination campaign, with vaccinations carried out on the first birthdays of children, the number of reported cases of measles was reduced to 545 in 2005, which is the lowest so far in Japan. We conducted a molecular epidemiological study of measles virus to determine the circulating measles virus genotypes in Japan since 1984. Different genotypes, C1, D3, D5, and H1, were the major strains isolated in outbreaks in 1984, 1987-1988, 1991-1993, and 2000, respectively. When measles was in the control phase, a sporadic outbreak was reported, but the causative virus was found to be of imported measles virus lineage. We also conducted a seroepidemiological study to investigate the persistence of vaccine-acquired immunity in Himeji City, Japan. Before 1990, vaccine coverage was 84.5% and it increased gradually, to 88.5% in 1991-1995, 92.7% in 1996-2000, and 94.6% after 2000. Measles outbreaks were observed annually before 1978 and in 1980, 1981, 1984, 1990, and 1996; there were no measles cases after 1997 in Himeji City. In 1994-1998, a serological study of 795 sera showed that measles neutralization test (NT) antibodies were sufficiently preserved, even 12 years after the first-dose immunization. In 1999-2003, 26 (3.7%) of 695 sera were negative for NT. The positive rate for measles NT decreased to approximately 90% as the elapsed time after the first-dose immunization increased to 6 or 7 years. The immunity obtained after receiving measles vaccine decays by 6-7 years after the first dose when the measles was controlled. A two-dose schedule of measles vaccine was implemented in Japan in 2006; we should continue molecular and serological surveillance.

Detection of respiratory syncytial virus genome by subgroups-A, B specific reverse transcription loop-mediated isothermal amplification (RT-LAMP).

Annual seasonal outbreaks of respiratory syncytial virus (RSV) infection occur every winter. Most patients are diagnosed clinically by a rapid detection kit for RSV protein(s) from nasopharyngeal secretion (NPS), but some problems have been reported on the specificity and sensitivity of such rapid detection kits. To ratify these issues, a sensitive, specific, simple, and rapid molecular based diagnostic method is expected to be introduced and we have developed a method to detect the RSV genome of subgroups A and B independently by reverse transcription loop-mediated isothermal amplification (RT-LAMP). We detected the genomic RNA corresponding approximately to 0.1 TCID 50 in the sample by RT-LAMP for both RSV subgroups under isothermal condition within 60 min after extraction of RNA. Specific DNA amplification was monitored by a real-time turbidimeter and the quantity of RNA was calculated. The RSV genome was detected in 47 of 50 NPS by RT-LAMP, and in 42 by nested RT-PCR, whereas virus isolation was positive for 29 and enzyme-linked immunoassay (EIA) for 34. RSV subgroup A was detected in 25 by RSV RT-LAMP A, RSV subgroup B in 23 by RSV RT-LAMP B, and dual infection with RSV subgroups A and B was identified in one case. They were confirmed with digestion with a specific restriction enzyme, Bgl II. The results showed the potential clinical feasibility of RT-LAMP as a useful diagnostic tool for the detection of RSV with high sensitivity similar to nested RT-PCR.

A simple method for the detection of measles virus genome by loop-mediated isothermal amplification (LAMP).

Approximately 20,000-30,000 measles patients were reported in a surveillance of infectious diseases because of low vaccine coverage of 80% in Japan. Among them, some were thought to be secondary vaccine failure (SVF) with generally mild or non-typical measles illness and sometimes became a source of further transmission. We have developed a new, sensitive, and rapid method to detect the measles virus genome by reverse transcription loop-mediated isothermal amplification (RT-LAMP). We examined 50 nasopharyngeal secretion (NPS) samples that were obtained during the 1999 outbreak and stored at -70 degrees C and fresh NPS, lymphocytes and sera from 11 patients in 2003. Total RNA was extracted from the samples and subjected to reverse transcription-polymerase chain reaction (RT-PCR) and RT-LAMP. We detected the genomic RNA corresponding to at least 0.01-0.04 TCID50, 30-100 copies in samples by RT-LAMP within 60 min after extraction of RNA, and all four genotypes isolated in Japan were equally amplified. Specific DNA amplification was monitored spectrophotometrically by real time turbidimeter and the quantity of RNA was calculated. Measles virus genome was detected in 44 of 50 stored NPS by RT-PCR and in 49 by RT-LAMP. The vaccine strain was discriminated from wild strains after sequencing the LAMP products. RT-LAMP is a useful rapid diagnostic method for the detection of measles virus without any special apparatus, showing higher sensitivity than RT-PCR, and expected to be applied for hospital-based infection control and for laboratory-based measles surveillance.

Rapid diagnostic method for detection of mumps virus genome by loop-mediated isothermal amplification.

Most mumps patients are clinically diagnosed without any virological examinations, but some diagnosed cases of mumps may be caused by other pathogens or secondary vaccine failure (SVF). To clarify these issues, a sensitive, specific, and rapid diagnostic method is required. We obtained 60 salivary swabs from 34 patients with natural infection during the course of the illness, 10 samples from patients with vaccine-associated parotitis, and 5 samples from patients with SVF. Total RNA was extracted and subjected to reverse transcription-PCR (RT-PCR) and loop-mediated isothermal amplification (LAMP) for genome amplification. We detected mumps virus RNA corresponding to 0.1 PFU by LAMP within 60 min after RNA extraction, with the same sensitivity as RT-nested PCR. Mumps virus was isolated in 30 of 33 samples within day 2, and mumps virus genome was amplified by LAMP in 32 of them. The quantity of virus titer was calculated by monitoring the time to reach the threshold of turbidity. The viral load decreased after day 3 and was lower in patients serologically diagnosed as having SVF with milder illness. Accuracy of LAMP for the detection of mumps virus genome was confirmed; furthermore, it is of benefit for calculating the viral load, which reflects disease pathogenesis.