Using guinea pig as a model for evaluation of equine influenza vaccine

Equine influenza is a highly contagious viral disease, specially among 1-5 years old naive horses. Vaccination is considered the best way to control the disease spread and outbreaks. Although foals are the main animal used for evaluation of equine influenza vaccines, guinea pigs were chosen as an alternative model in the present work, as they have a negligible antibody titer against equine influenza virus and are cheaper and easier to handle than foals. Five equine influenza vaccine batches were evaluated in two animal models, foals and guinea pigs, by injection of two doses/animal with 4 weeks apart using 2 mL/animal/dose and evaluation of immune responses by hemagglutination inhibition test and enzyme-linked immunosorbent assay. On the 7th week post vaccination, equine influenza antibodies titers reached maximum values of 9-10.2 and 8.7-10 hemagglutination inhibition units for foals and guinea pigs, respectively; sample/negative ratios were 0.126-0.464 and 0.128-0.445 for both animals, respectively. The use of guinea pigs as an animal model for the evaluation of equine influenza vaccines could be recommended instead of foals.

La gripe equina es una enfermedad viral muy contagiosa, especialmente entre los caballos jóvenes de 1 a 5 años de edad. La vacunación se considera la mejor forma de controlar la propagación y los brotes de la enfermedad. Aunque los potros son el principal animal utilizado para la evaluación de vacunas contra la gripe equina, en el presente trabajo se eligieron cobayos como modelo alternativo, ya que tienen un título insignificante de anticuerpos contra el virus de la gripe equina y son más baratos y fáciles de manejar que los potros. Se evaluaron cinco lotes de vacunas contra la gripe equina en dos modelos animales, potros y cobayos, mediante la inyección de dos dosis/animal con 4 semanas de intervalo utilizando 2 mL/animal/dosis y la evaluación de las respuestas inmunitarias mediante la prueba de inhibición de la hemaglutinación y el ensayo inmunoenzimático. En la 7ª semana posvacunación, los títulos de anticuerpos contra la gripe equina alcanzaron valores máximos de 9-10,2 y 8,7-10 unidades de inhibición de la hemaglutinación para potros y cobayos, respectivamente; las relaciones muestras/negativos fueron de 0,126-0,464 y 0,128-0,445 para ambos animales, respectivamente. Podría recomendarse el uso de cobayos como modelo animal para la evaluación de vacunas contra la gripe equina, en lugar de potros.

Preparation and evaluation of formalized bivalent Newcastle and Salmonella poultry vaccine

This study was conducted to prepare and evaluate the potency of different inactivated vaccine formulations that protect chickens against Salmonella Enteritidis and Newcastle disease virus using Montanide as adjuvant. Protection and the humoral immune response of prepared vaccines against Salmonella Enteritidis and Newcastle disease virus was evaluated and compared to imported vaccine. In this study, different formulae of Salmonella Enteritidis and Newcastle disease vaccines were prepared and compared with the imported one by measuring the antibody titer against Newcastle disease virus by hemagglutination inhibition test and the antibody titer against Salmonella Enteritidis using Enzyme Linked Immunosorbent Assay. On the other hand, the protection percentages against Newcastle disease and Salmonella Enteritidis were recorded to determine the best effective formula. The highest hemagglutination inhibition antibody level against NDV at first week was recorded for the prepared combined Newcastle disease and Salmonella Enteritidis vaccine (4.2 log2) followed by the prepared monovalent Newcastle disease (3.4 log2); the lowest antibody level (3.1 log2) was obtained with the imported vaccine. A gradual increase was observed in all groups to 7.1 log2, 6.8 log2 and 6.4 log2 at fourth week post vaccination, respectively. The antibody titer against Salmonella Enteritidis was 552 for the prepared combined Salmonella Enteritidis and Newcastle disease, followed by the prepared monovalent Salmonella Enteritidis (477) at first week post vaccination; the antibody titer obtained for the imported vaccine was 477. There was a gradual increase to 1456, 1406 and 1130 at fourth week post vaccination, respectively. Prepared combined vaccines gave the highest protection percentage, followed by prepared monovalent types and finally imported vaccines. Vaccination by the prepared combined Salmonella Enteritidis and Newcastle disease vaccine may be a way to increase the resistance of birds to Salmonella and Newcastle and to decrease the shedding rate(AU)

Este estudio se llevó a cabo para preparar y evaluar la potencia de diferentes formulaciones de vacunas inactivadas que protegen a los pollos contra Salmonella Enteritidis y el virus de la enfermedad de Newcastle utilizando Montanide como adyuvante. Se evaluó la protección y la respuesta inmune humoral de las vacunas preparadas contra Salmonella Enteritidis y el virus de la enfermedad de Newcastle y se comparó con la vacuna importada. En este estudio se prepararon diferentes fórmulas de vacunas contra Salmonella Enteritidis y la enfermedad de Newcastle y se compararon con la importada midiendo el título de anticuerpos contra el virus de la enfermedad de Newcastle mediante la prueba de inhibición de la hemaglutinación y el título de anticuerpos contra Salmonella Enteritidis mediante ELISA. Por otra parte, se registraron los porcentajes de protección contra la enfermedad de Newcastle y Salmonella Enteritidis para determinar la fórmula más eficaz. El mayor nivel de anticuerpos inhibidores de la hemaglutinación contra el virus de la enfermedad de Newcastle, en la primera semana, se registró con la vacuna combinada preparada contra la enfermedad de Newcastle y Salmonella Enteritidis (4,2 log2), seguida de la vacuna monovalente preparada contra la enfermedad de Newcastle (3,4 log2); el menor nivel de anticuerpos (3,1 log2) se obtuvo con la vacuna importada. Se observó un aumento gradual en todos los grupos hasta alcanzar 7,1 log2, 6,8 log2 y 6,4 log2 en la cuarta semana tras la vacunación, respectivamente. El título de anticuerpos contra Salmonella Enteritidis fue de 552 para la vacuna combinada preparada contra la Salmonella Enteritidis y enfermedad de Newcastle, seguida por la vacuna monovalente preparada contra Salmonella Enteritidis (477) en la primera semana después de la vacunación; el título de anticuerpos obtenido con la vacuna importada fue de 477. Hubo un aumento gradual hasta 1456, 1406 y 1130 en la cuarta semana después de la vacunación, respectivamente. Las vacunas combinadas preparadas dieron el mayor porcentaje de protección, seguidas por los tipos monovalentes preparados y, por último, por las vacunas importadas. La vacunación con la vacuna combinada preparada contra la Salmonella Enteritidis y la enfermedad de Newcastle puede ser una forma de aumentar la resistencia de las aves a la Salmonella y Newcastle y de disminuir la tasa de excreción(AU)

Surveillance of antibody level of influenza among physical examination population of Shenzhen City from 2014 to 2018 / 上海预防医学

Objective To provide the basis for influenza epidemic prevention and control by monitoring the antibody level of influenza among the general population in Dapeng New District of Shenzhen City. Methods A total of 1 350 serum samples of people were collected ten times from 2014 to 2018, and the antibody level was tested by hemagglutination-inhibition test. Results During 2014-2018 years, only the positive rate of antibody to H3N2 was above 60%.The positive rates of H1N1, H3N2, BV and BY were 50.0%, 85.6%, 35.4% and 45.6%, respectively, and the geometric mean titers (GMT) of antibody were 8.2, 81.5, 3.9 and 6.4, respectively.Influenza antibody titers of 1 : 160 and 1 : 320 were mainly distributed in influenza H3N2.The antibody level of BV and BY in age group 0~4 years was 29.0% and 30.4% separately. Conclusion It is imperative to enhance the surveillance of antibody level of influenza among general population in Dapeng New District, to investigate the epidemic development trend of influenza constantly, and to prevent and control the outbreak of influenza epidemics.

Antibody responses after vaccination against equine influenza in Korea in 2016–2018 / 대한수의학회지

Equine influenza (EI) is the main cause of respiratory illness in equines across the globe and is caused by equine influenza A virus (EIV-A), which has impacted the equine industry internationally because of the marginal mortality and high morbidity. In the present study, the immune responses after equine influenza vaccination were evaluated in 4,144 horses in Korea using the hemagglutination inhibition (HI) assay. The equine influenza virus (EIV), A/equine/South Africa/4/03 (H3N8), was used as the antigen in the HI assay. The mean seropositive rates were 89.2% (97.4% in 2016, 77.6% in 2017, and 92.4% in 2018). This paper highlights the advances in understanding the effects of vaccines and control strategies for mitigating the emerging menace by EIV.

Establishment of a high sensitive indirect ELISA for detecting specific antibodies against H9 subtype avian influenza virus / 生物工程学报

H9 subtype avian influenza virus causes worldwide epidemic, resulting in enormous economic losses of poultry production. In the present study, an indirect ELISA method was established for more accurate and specific detection. The recombinant protein of the globular head domain of HA of H9 subtype avian influenza virus was used as antigen. Specific blocking buffers and dilution buffers were determined to increase the sensitivity and specificity. The sensitivity of ELISA was higher than that of hemagglutination inhibition (HI) test. The coating antigen is very specific and no cross-reactivity with positive serum against H3N2, H5N2 and H7N9 subtype influenza viruses, Newcastle disease virus, avian infectious bronchitis virus, avian infectious disease virus, and egg drop syndrome virus. Two hundred of clinical sera samples were examined. The results indicate the coincidence rate between ELISA and HI test reached 97%. In addition, there was a positive correlation between OD450 values and the logarithm of HI titer to the base 2 of an individual serum sample (R2=0.981 1).

Chikungunya virus infection in West Bengal, India.

Background: Chikungunya virus has recently re-emerged in India. Objectives: Assess prevalence of Chikungunya. Materials and Methods: Study conducted from April 2011 to September 2011. Two hundred and six patients (206) of both sexes (100 males and 106 females) of all age groups studied. Serum separated and CHIKV MAC IgM ELISA and Hemagglutination inhibition assay done. Results: 76 cases (36.89%) sero-positive by both the methods. Conclusion: Re-emergence and resurgence of the Chikungunya virus requires continuous monitoring.

Prevalence of antibodies to equine alphaviruses in the State of Pará, Brazil / Prevalência de anticorpos para alphavirus em equinos do estado do Pará, Brasil

The State of Pará comprises 26% of Brazilian Amazon region, where a large diversity of arboviruses has been described. This study sought to assess the prevalence and distribution of hemagglutination inhibition (HI) antibodies against antigens of four alphaviruses (Togaviridae: Alphavirus ) from the species: Eastern equine encephalitis (EEEV), Western equine encephalitis (WEEV), Mayaro virus (MAYV), and Mucambo virus (MUCV) in 753 serum samples of horses in Pará State, Brazil. All investigated arboviruses were detected and indicate that horses are susceptible to these alphaviruses, and show evidences of their active circulation in farm animals in the Brazilian Amazon.(AU)

O estado do Pará corresponde a 26% da Amazônia brasileira, onde uma grande diversidade de arbovírus foi descrita. Este estudo procurou avaliar a prevalência e a distribuição de anticorpos inibidores da hemaglutinação (IH) contra antígenos de quatro alfavirus (Togaviridae: Alphavirus ), das espécies: Vírus da encefalite equina do leste (EEEV), Vírus da encefalite equina do oeste (WEEV), Vírus mayaro (MAYV) e Vírus mucambo (MUCV), de 753 amostras de soro de equinos no estado do Pará, Brasil. Todos os arbovirus pesquisados foram detectados, indicando que os equinos são suscetíveis a esses Alphavirus e mostrando evidências de sua circulação ativa em animais de fazenda na Amazônia brasileira.(AU)

Evaluation of the proficiency of laboratories for detection of rabbit hemorrhagic disease virus antibody / 中国实验动物学报

Objective Through the detection of rabbit hemorrhagic disease virus( RHDV) antibody, to investigate the capacity of experimental animal quality control laboratories, so as to improve their detection proficiency.Methods According to the program approved by CNAS, the screened samples were numbered randomly and tested for their stability and homogeneity.The random samples were issued to the participant laboratories with the Standard Operation Procedure ( SOP) .The participant laboratories must submit the test reports and original records in time.The feedback results were judged by the rate of concordance with the anticipated results.Results Twenty laboratories from 14 provinces were en-rolled in the evaluation, and all of them submitted detection results on time.ELISA methods were used in 14 laboratories, and hemagglutination inhibition ( HAI) assay was used in 6 laboratories.The results of 17 laboratories were marked as pass or excellent, with a rate of pass of 85%.Conclusions The ability for detection of RHDV antibody in animal test labora-tories in China is high.The implementation of capacity testing can reflect the level of quality control laboratories.

Correlations in the results of virus neutralization test, hemagglutination inhibition test, and enzyme-linked immunosorbent assay to determine infectious bronchitis virus vaccine potency

The virus neutralization (VN) test was used to determine potency of the infectious bronchitis (IB) vaccine. The results of VN, hemagglutination inhibition (HI), and enzyme-linked immunosorbent assay (ELISA) were compared with those of the IBV M41. The r² values between VN and HI titers and the ELISA antibody titer were 0.8782 and 0.0336, respectively, indicating a high correlation between VN and HI, but not VN and ELISA. The Cohen's kappa coefficient between the VN titer of 2 log₁₀ and HI titer of 5 log₂ was 0.909. Our results showed that VN could be replaced with HI for testing the potency of IBV M41.

Biological Property of Recombinant Hemagglutinin-Neuraminidase Protein of Avian Paramyxovirus Type 6 Expressed by Recombinant Baculovirus

Hemagglutination inhibition (HI) test employing whole virus antigen is a prescribed serological test for serotyping, diagnosis and surveillance for avian paramyxoviruses (APMVs). For use as alternative to the virus antigen, hemagglutinin-neuraminidase (HN) protein gene of the wild duck isolate APMV-6/WB12-163FS of APMV serotype 6 (APMV-6) was amplified, cloned and expressed in Spodoptera frugiperda insect cells. The HN gene of 1,842 bps in length showed nucleotide and amino acid homology of 93.4% and 97.1%, respectively with that of APMV-6 prototype strain. Putative sialic acid binding motif and potential N-linked glycosylation sites were conserved. In Western blot analysis, the expressed protein had a molecular mass of 66 kDa and reacted specifically with antiserum to APMV-6. In addition, the recombinant HN protein showed biological properties such as hemagglutination (HA) and elution. The recombinant HN protein produced from infected cells showed high HA titers (approximately 2(13) HA unit/ml). The HA activity of the recombinant HN protein was inhibited by antisera to APMV-6. In cross HA inhibition test, the recombinant HN protein had the highest titers with antisera to homologous APMV serotype, although there was weak cross reaction with some of antisera to other APMV serotypes. Our results indicated that recombinant APMV-6 HN protein would have the potential as alternative to the APMV-6 antigen in HI assays.

Immunogenicity of hemagglutinin of H7 N9 expressed in yeast Pichia pastoris / 军事医学

Objective To express the hemagglutinin of H7N9 in Pichia pastoris and analyze its immunogenicity. Methods The HA [1 -525 amino acids(aa)] of H7N9 [A/Hangzhou/1/2013(H7N9)] lacking the C-terminal transmembrane anchor-coding sequence was amplified by PCR and cloned into the expression vector pPICZαA.The plasmid pPICZ-HA7-S-was transformed into P.pastoris and the HA1-525 was detected by ELISA.Then the HA1-525 was precipitated by PEG20000.After immunization with the HA1-525 , the anti-HA7 antibody in mouse serum was detected by ELISA and hemagglutinin inhibition ( HI) test.Results The HA1-525 was expressed in P.pastoris after being induced with methanol. Western blotting confirmed that there were specific dispersion bands and the molecular weight of HA1-525 decreased to 58 × 103 after being digested by endo H.Anti-HA7 antibody was found in serum of HA1-525 immunized mice and the hemaggluti-nation-inhibition titers reached 1∶700 after the third doses.Conclusion This study shows the HA1-525 expressed in P.pastoris can induce the neutralizing antibody in mice.

Presence of resiiratory viruses in equines in Brazil / Presença de vírus respiratórios em equinos do Brasil

Equines are susceptible to respiratory viruses such as influenza and parainfluenza. Respiratory diseases have adversely impacted economies all over the world. This study was intended to determine the presence of influenza and parainfluenza viruses in unvaccinated horses from some regions of the state of São Paulo, Brazil. Blood serum collected from 72 equines of different towns in this state was tested by hemagglutination inhibition test to detect antibodies for both viruses using the corresponding antigens. About 98.6% (71) and 97.2% (70) of the equines responded with antibody protective titers (≥ 80 HIU/25µL) H7N7 and H3N8 subtypes of influenza A viruses, respectively. All horses (72) also responded with protective titers (≥ 80) HIU/25µL against the parainfluenza virus. The difference between mean antibody titers to H7N7 and H3N8 subtypes of influenza A viruses was not statistically significant (p > 0.05). The mean titers for influenza and parainfluenza viruses, on the other hand, showed a statistically significant difference (p < 0.001). These results indicate a better antibody response from equines to parainfluenza 3 virus than to the equine influenza viruses. No statistically significant differences in the responses against H7N7 and H3N8 subtypes of influenza A and parainfluenza 3 viruses were observed according to the gender (female, male) or the age (≤ 2 to 20 years-old) groups. This study provides evidence of the concomitant presence of two subtypes of the equine influenza A (H7N7 and H3N8) viruses and the parainfluenza 3 virus in equines in Brazil. Thus, it is advisable to vaccinate equines against these respiratory viruses.

Os equinos são susceptíveis aos vírus respiratórios, como o vírus influenza, e também tem sido citado o vírus parainfluenza. Doenças respiratórias têm impactado a economia em todo mundo. Este estudo intencionou determinar a presença dos vírus influenza e parainfluenza em equinos não vacinados de certas regiões do Estado de São Paulo, Brasil. Os soros coletados de 72 equinos, de diferentes cidades deste Estado, foram submetidos ao teste de Inibição da Hemaglutinação (IH) com objetivo de detectar anticorpos contra os referidos vírus, usando antígenos correspondentes. Cerca de 98,8% (72) e 97,2% (70) desses equinos responderam com títulos protetores (≥ 80 UIH/25µL) para os subtipos H7N7 e H3N8 de vírus influenza, respectivamente. Todos equinos (72) responderam com títulos protetores (≥ 80 UIH/25µL) contra o vírus parainfluenza 3. A diferença entre as médias de anticorpos contra o vírus influenza A não foi estatisticamente significante (p > 0,05). As médias de títulos dos vírus influenza e parainfluenza, por outro lado, demonstraram diferença estatisticamente significante (p < 0,001). Esses resultados indicam melhor resposta de anticorpos pelos equinos ao vírus parainfluenza 3 do que ao vírus da influenza equina. Nenhuma diferença estatística foi observada nas respostas contra os vírus da influenza equina A (H7N7 e H3N8) e parainfluenza 3, com relação ao gênero (fêmeas e machos) e grupo etário (≤ 2 até 20 anos) nos equinos avaliados. Este estudo fornece evidência da presença concomitante dos dois subtipos vírus influenza A (H7N7 e H3N8) e do parainfluenza 3 em cavalos no Brasil. Portanto, é aconselhável a vacinação dos cavalos contra esses vírus respiratórios.

Seroprevalence of flaviviruses antibodies in water buffaloes (Bubalus bubalis) in Brazilian Amazon

The state of Pará encompasses 26% of Brazilian Amazon where an enormous diversity of arboviruses has been found. This study aimed to assess the prevalence and distribution of hemagglutination-inhibition antibodies against antigens of six Flavivirus (yellow fever virus, Ilheus virus, Saint Louis encephalitis virus, Cacipacore virus, Bussuquara virus and Rocio virus) in water buffaloes in Pará state, Brazil. The prevalence of antibodies in these farm animals is important to determine the circulating arboviruses.

Seroprevalence of flaviviruses antibodies in water buffaloes (Bubalus bubalis) in Brazilian Amazon

The state of Pará encompasses 26% of Brazilian Amazon where an enormous diversity of arboviruses has been found. This study aimed to assess the prevalence and distribution of hemagglutination-inhibition antibodies against antigens of six Flavivirus (yellow fever virus, Ilheus virus, Saint Louis encephalitis virus, Cacipacore virus, Bussuquara virus and Rocio virus) in water buffaloes in Pará state, Brazil. The prevalence of antibodies in these farm animals is important to determine the circulating arboviruses.

Immunogenicity of Influenza Vaccine in Colorectal Cancer Patients / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Although influenza is regarded as a major cause of morbidity and mortality in immunocompromised patients, vaccine coverage remains poor. We evaluated the immunogenicity of influenza vaccines in colorectal cancer patients. MATERIALS AND METHODS: In this study, 40 colorectal cancer patients who received an influenza vaccine at the Korea Cancer Center Hospital during the 2009-2010 and 2010-2011 influenza seasons were analyzed. The blood samples were collected at prevaccination and 30 days post vaccination, and antibody titers were measured using the hemagglutination-inhibition tests. RESULTS: In the 2009-2011 season, the seroprotection rate for H1N1 (94.7%) was significantly higher than that for H3N2 (42.1%) and B (47.3%). The seroconversion rate was 52.6%, 26.3%, and 36.8% for H1N1, H3N2, and B, respectively. Fold increase of geometric mean titer (MFI) was 3.86, 1.49, and 3.33 for H1N1, H3N2, and B, respectively. In the 2010-2011 season, the seroprotection rate for H1N1 (57.1%) was significantly higher than that for H3N2 (52.4%) and B (38.1%). The seroconversion rate was 52.4%, 47.6% and 33.3% for H1N1, H3N2, and B, respectively. MFI was 12.29, 3.62 and 4.27 for H1N1, H3N2, and B, respectively. CONCLUSION: Our study cohort showed an acceptable immune response to an influenza vaccine without significant adverse effects, supporting the recommendation for annual influenza vaccination in colorectal cancer patients.

Change s of haemagglutination inhibitionan tibody level within one month after in fluenza A (H1N 1) vaccination / 中华微生物学和免疫学杂志

Objective To find the changes of haemagglutination inhibition ( HI ) antibody level against A/California/07/2009 (H1N1) within one month after pandemic A/H1N1 influenza vaccine (A/H1N1InfV) vaccination, and to provide data for drawing up immunization protocols against novel influenza . Methods The HI antibodies against A/California/07/2009 (H1N1) in sera from the inoculated subjects were tested by HI test .The geometric mean titer ( GMT) , geometric mean increase ( GMI) , seroconversion (SC) rate, seroprotection (SP) rate of HI antibodies were compared among the sera collected on day 3, 7, 14, 30 post vaccination .Results 961 participants were injected with A/H1N1InfV.In subjects aged 3 to 11 years, the antibody level peaked on day 14 post vaccination, but neither on day 14 nor on day 30, the lower bound of the two -sided 95%CI for the SP rate could fulfill the criteria of the FDA for influenza vac-cine.In subjects aged 12 to 60 years, the antibody level peaked on day 14 post vaccination and the SC rate , SP rate and GMI fulfilled the criteria of the European Medicines Agency ( EMEA) and the FDA for influenza vaccine. In subjects aged more than 60 years, the antibody level peaked on day 30 post vaccination , and the SC rate, SP rate and GMI on day 30 fulfilled the criteria of the EMEA and the FDA .Conclusion One dose A/H1N1InfV vaccination was able to induce enough protection on day 14 for subjects aged 12 to 60 years, on day 30 for subjects aged more than 60 years;however , for subjects aged 3 to 11 years who were antibody-negative at baseline , the lower bound of the two-sided 95%CI for the SP rate on day 14 and day 30 couldn′t fulfill the criteria of the FDA for influenza vaccine .

Preparation and diagnostic utility of a hemagglutination inhibition test antigen derived from the baculovirus-expressed hemagglutinin-neuraminidase protein gene of Newcastle disease virus

A recombinant hemagglutinin-neuraminidase (rHN) protein from Newcastle disease virus (NDV) with hemagglutination (HA) activity was expressed in Spodoptera frugiperda cells using a baculovirus expression system. The rHN protein extracted from infected cells was used as an antigen in a hemagglutination inhibition (HI) test for the detection and titration of NDV-specific antibodies present in chicken sera. The rHN antigen produced high HA titers of 2(13) per 25 microL, which were similar to those of the NDV antigen produced using chicken eggs, and it remained stable without significant loss of the HA activity for at least 12 weeks at 4degrees C. The rHN-based HI assay specifically detected NDV antibodies, but not the sera of other avian pathogens, with a specificity and sensitivity of 100% and 98.0%, respectively, in known positive and negative chicken sera (n = 430). Compared with an NDV-based HI assay, the rHN-based HI assay had a relative sensitivity and specificity of 96.1% and 95.5%, respectively, when applied to field chicken sera. The HI titers of the rHN-based HI assay were highly correlated with those in an NDV-based HI assay (r = 0.927). Overall, these results indicate that rHN protein provides a useful alternative to NDV antigen in HI assays.

Evaluation of immunogenicity of the 2008-2009 seasonal influenza vaccines by microneutralization test / 소아과

PURPOSE: For evaluating the immunogenicity of an influenza vaccine, the microneutralization (MN) test has a higher sensitivity and specificity as compared to the hemagglutination inhibition (HI) test. However, the MN test is more time consuming and is difficult to standardize. We performed the MN test to determine its usefulness as an alternative or complementary test to the HI test for evaluating the immunogenicity of influenza vaccines. METHODS: We compared the MN test with the HI test using 50 paired samples taken from a previous clinical study (2008-2009) in Korean children under 18 years of age. RESULTS: The linear correlation coefficients of the 2 tests for H3N2, H1N1, and influenza B were 0.69, 0.70, and 0.66, respectively. We identified a high index of coincidence between the 2 tests. For an influenza vaccine, the postvaccination seroprotection rates and seroconversion rates determined by the MN test were 78.0% and 96.0%, 90% and 42.0%, and 42.0% and 48.0% for H3N2, H1N1, and influenza B, respectively. Geometric mean titer fold increases of H3N2, H1N1, and influenza B were 2.89, 5.04, and 4.29, respectively, and were 2.5-fold higher. We obtained good results in the evaluation of the immunogenicity of the 2008-2009 seasonal influenza vaccines. CONCLUSION: We found that the MN test was as effective as the HI test. Therefore, we suggest that the MN test can be used as an alternative or complementary test to the HI test for evaluating the immunogenicity of influenza vaccines.

Erythrocyte Binding Preference of Human Pandemic Influenza Virus A and Its Effect on Antibody Response Detection

BACKGROUND: Validation of hemagglutination inhibition (HI) assays is important for evaluating antibody responses to influenza virus, and selection of erythrocytes for use in these assays is important. This study aimed to determine the correlation between receptor binding specificity and effectiveness of the HI assay for detecting antibody response to pandemic influenza H1N1 (pH1N1) virus. METHODS: Hemagglutination (HA) tests were performed using erythrocytes from 6 species. Subsequently, 8 hemagglutinating units of pH1N1 from each species were titrated by real-time reverse transcription-PCR. To investigate the effect of erythrocyte binding preference on HI antibody titers, comparisons of HI with microneutralization (MN) assays were performed. RESULTS: Goose erythrocytes showed most specific binding with pH1N1, while HA titers using human erythrocytes were comparable to those using turkey erythrocytes. The erythrocyte binding efficiency was shown to have an impact on antibody detection. Comparing MN titers, HI titers using turkey erythrocytes yielded the most accurate results, while those using goose erythrocytes produced the highest geometric mean titer. Human blood group O erythrocytes lacking a specific antibody yielded results most comparable to those obtained using turkey erythrocytes. Further, pre-existing antibody to pH1N1 and different erythrocyte species can distort HI assay results. CONCLUSIONS: HI assay, using turkey and human erythrocytes, yielded the most comparable and applicable results for pH1N1 than those by MN assay, and using goose erythrocytes may lead to overestimated titers. Selection of appropriate erythrocyte species for HI assay allows construction of a more reliable database, which is essential for further investigations and control of virus epidemics.