SARS-CoV-2 and influenza: a comparative overview and treatment implications / SARS-CoV-2 e influenza: revisión comparativa e implicaciones del tratamiento

Abstract Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and Alphainfluenzavirus are RNA viruses that cause coronavirus disease-19 and influenza, respectively. Both viruses infect the respiratory tract, show similar symptoms, and use surface proteins to infect the host. Influenza requires hemagglutinin and neuraminidase to infect, whereas SARS-CoV-2 uses protein S. Both viruses depend on a viral RNA polymerase to express their proteins, but only SARS-CoV-2 has a proofreading mechanism, which results in a low mutation rate compared to influenza. E1KC4 and camostat mesylate are potential inhibitors of SARS-CoV-2 S protein, achieving an effect similar to oseltamivir. Due to the SARS-CoV-2 low mutation rate, nucleoside analogs have been developed (such as EIDD-2801), which insert lethal mutations in the viral RNA. Furthermore, the SARS-CoV-2 low mutation rate suggests that a vaccine, as well as the immunity developed in recovered patients, could provide long-lasting protection compared to vaccines against influenza, which are rendered obsolete as the virus mutates.

Resumen La enfermedad por coronavirus de 2019 y la influenza son causadas por virus ARN: coronavirus tipo 2 del síndrome respiratorio agudo grave (SARS-CoV-2) y Alphainfluenzavirus, respectivamente. Ambos virus infectan el tracto respiratorio, presentan síntomas similares y emplean proteínas de superficie para infectar al huésped. El virus de la influenza requiere de hemaglutinina y neuraminidasa para infectar, mientras que el SARS-CoV-2 utiliza la proteína S. Ambos virus dependen de la ARN polimerasa viral para expresar sus proteínas, pero solo el SARS-CoV-2 cuenta con un mecanismo de corrección de errores, por lo que presenta una baja tasa de mutaciones en comparación con el virus de la influenza. E1KC4 y el mesilato de camostat son inhibidores potenciales de la proteína S del SARS-CoV-2, obteniendo un efecto similar al de oseltamivir. Aprovechando la baja tasa de mutación del SARS-CoV-2, se han desarrollado análogos de nucleósidos (como el fármaco EIDD-2801) que insertan mutaciones letales en el ARN viral. Además, la baja tasa de mutación del SARS-CoV-2, obteniendo un efecto similar al de oseltamivir sugiere que las vacunas desarrolladas, así como la inmunidad generada en pacientes recuperados, podrían brindar protección prolongada, en comparación con las vacunas desarrolladas contra la influenza, que resultan obsoletas frente a una cepa mutada.

Influenza A virus exposure may cause increased symptom severity and deaths in coronavirus disease 2019 / 中华医学杂志(英文版)

BACKGROUND@#The coronavirus disease 2019 (COVID-19) outbreak occurred during the flu season around the world. This study aimed to analyze the impact of influenza A virus (IAV) exposure on COVID-19.@*METHODS@#Seventy COVID-19 patients admitted to the hospital during January and February 2020 in Wuhan, China were included in this retrospective study. Serum tests including respiratory pathogen immunoglobulin M (IgM) and inflammation biomarkers were performed upon admission. Patients were divided into common, severe, and critical types according to disease severity. Symptoms, inflammation indices, disease severity, and fatality rate were compared between anti-IAV IgM-positive and anti-IAV IgM-negative groups. The effects of the empirical use of oseltamivir were also analyzed in both groups. For comparison between groups, t tests and the Mann-Whitney U test were used according to data distribution. The Chi-squared test was used to compare disease severity and fatality between groups.@*RESULTS@#Thirty-two (45.71%) of the 70 patients had positive anti-IAV IgM. Compared with the IAV-negative group, the positive group showed significantly higher proportions of female patients (59.38% vs. 34.21%, χ = 4.43, P = 0.035) and patients with fatigue (59.38% vs. 34.21%, χ = 4.43, P = 0.035). The levels of soluble interleukin 2 receptor (median 791.00 vs. 1075.50 IU/mL, Z = -2.70, P = 0.007) and tumor necrosis factor α (median 10.75 vs. 11.50 pg/mL, Z = -2.18, P = 0.029) were significantly lower in the IAV-positive group. Furthermore, this group tended to have a higher proportion of critical patients (31.25% vs. 15.79%, P = 0.066) and a higher fatality rate (21.88% vs. 7.89%, P = 0.169). Notably, in the IAV-positive group, patients who received oseltamivir had a significantly lower fatality rate (0 vs. 36.84%, P = 0.025) compared with those not receiving oseltamivir.@*CONCLUSIONS@#The study suggests that during the flu season, close attention should be paid to the probability of IAV exposure in COVID-19 patients. Prospective studies with larger sample sizes are needed to clarify whether IAV increases the fatality rate of COVID-19 and to elucidate any benefits of empirical usage of oseltamivir.

Comparison of the direct fluorescence assay and real-time polymerase chain reaction for the detection of influenza virus A and B in immunocompromised patients

OBJECTIVE: This study evaluated the diagnostic performance of two methods for the detection of influenza virus in immunocompromised transplant patients. METHODS: A total of 475 respiratory samples, 236 from patients in a hematopoietic stem cell transplantation program and 239 from kidney transplant patients, were analyzed by a direct fluorescence assay and the Centers for Disease Control real-time polymerase chain reaction protocol for influenza A and B detection. RESULTS: Influenza detection using either method was 7.6% in the hematopoietic stem cell transplant group and 30.5% in the kidney transplant patient group. Influenza detection by real-time polymerase chain reaction yielded a higher positive rate compared with fluorescence than that reported by other studies, and this difference was more pronounced for influenza A. The fluorescence assay sensitivity, specificity, positive and negative predictive values, and kappa coefficient were 17.6%, 100%, 1, 0.83, and 0.256, respectively, and lower detection rates occurred in the kidney transplant patients. CONCLUSIONS: The real-time polymerase chain reaction performance and the associated turnaround time for a large number of samples support the choice of this method for use in different routine diagnostic settings and influenza surveillance in high-risk patients. .

Evaluation of a Rapid Detection Influenza Virus A Antigens Kit Using Paired Serum Antibody Test

PURPOSE: To evaluate the feasibility for gold immunochromatographic assay (GICA) in rapid detection of influenza virus A infection. MATERIALS AND METHODS: Seventy-three patients were enrolled. All patients contributed nasopharyngeal secretions and paired serum samples. Nasopharyngeal secretions was used for colloidal gold immunochromatographic rapid assay for influenza A virus immediately after the collection of specimen. Paired serum samples were used for the hemagglutination inhibition assay at the Centers for Disease Control and Prevention influenza network laboratory in Beijing. RESULTS: Compare GICA test to hemagglutination inhibition (HI) assay, the Kappa value was 0.402 and the p value in the paired chi2 test was higher than 0.05. Therefore, the difference was not statistically significant. The sensitivity of GICA was 50.0% and the specificity was 90.2%, and the negative predictive value was 90.2%. CONCLUSION: The sensitivity for Influenza A antigen detection by using GICA is relatively low, the specificity is relatively satisfactory.

Resolution of immune response by recombinant transforming growth factor-beta (rTGF-β) during influenza A virus infection.

Background & objectives: Replication of influenza A virus in the respiratory tract leads to cell damage and liberation of cytokines and chemokines. The in vivo cytokine induction and modulation by recombinant transforming growth factor- β1 (rTGF-β1) has not been studied. Therefore, in the present study the effect of rTGF-β1, a potent immunomodulatory cytokine which has anti-inflammatory properties and downregulates the release of inflammatory molecules, against influenza-virus infection in the airway of mice was investigated. Methods: rTGF-β1 was administered intravenously to mice with concomitant intranasal infection of influenza A/Udorn/317/72 (H3N2) virus, and the survival rate, virus titre, histopathological changes and levels of factors regulating inflammation in the airway fluid were analysed. Result: The immune response to influenza A virus was characterized by an influx of both macrophages and lymphocytes into the lungs of the infected host. rTGF-β1 significantly suppressed virus multiplication and improved the survival rate of mice. rTGF-β1 downregulated infiltration of neutrophils and the release of inflammatory molecules, such as interferon-gamma (IFN-γ), interleukin-1 β (IL-1β) and stimulated release of IL-10 that potentiates anti-inflammatory response into airway. Interpretation & conclusions: A generalized pulmonary inflammation does not contribute to viral clearance but represents an immunological background within which antiviral immunity operates. Treatment with rTGF-β1 reduced macrophage count and neutrophils influx in lungs of infected mice.

Prevalencia serológica del virus de influenza A en cerdos en Argentina durante la temporada 2002: evaluación mediante inhibición de la hemaglutinación y ELISA / Seroprevalence of the swine Influenza virus in fattening pigs in Argentina in the 2002 season: evaluation by hemagglutination-inhibition and ELISA tests

Se evaluó la prevalencia serológica del virus de influenza mediante las pruebas de inhibición de la hemaglutinación (IHA) y ELISA para los subtipos H1N1 y H3N2 en 13 granjas porcinas de Argentina. Se compararon los resultados obtenidos mediante ambas pruebas en términos individuales y de establecimientos. La prevalencia individual por la técnica de IHA fue de 38,46% a 100% para H1 y de 7,69% a 100% para H3. Por la técnica de ELISA, la prevalencia individual fue de 2,33% a 6,9% para H1 y de 9,65% a 48% para H3. No se observaron diferencias significativas entre ambas técnicas a escala de granja (H1: p=0,20; H3: p=0,11). La concordancia entre las pruebas fue nula al tomar como unidad de referencia el animal (H1: 0,005; H3: 0,070), mientras que en términos de establecimiento fue escasa (H1: 0,350; H3: 0,235). Considerando la alta prevalencia individual obtenida por la prueba de IHA y la alta sensibilidad de esta técnica, se podría sugerir que en las poblaciones porcinas de la Argentina circularon cepas virales humanas o cepas porcinas con gran proximidad filogenética a las utilizadas en este estudio desde el año 2002.

The seroprevalence of the Influenza virus against H1N1 and H3N2 was determined by the hemagglutination-inhibition test (HI) and a commercial swine influenza ELISA kit, in 13 Argentinean swine herds. The results of within-herd and between-herd prevalence obtained by both tests were statistically correlated. The within-herd prevalence observed by the HI test varied from 38.46 to 100% against H1 and 7.69 to 100% for H3. When the within-herd prevalence was measured with the ELISA test, it varied from 2.33 to 6.9% for H1 and 9.65 to 48% for H3. No statistical differences were observed at herd level between HI and ELISA (H1: p = 0. 20; H3: p=0.11). No agreement between HI and ELISA detected prevalence was observed when the within-herd prevalence was compared (H1: 0.005; H3: 0.070), while the agreement at herd level was considered poor (H1: 0,350; H3: 0,235). The high within-herd prevalence values observed with the HI test and the high sensibility of this test might show that human strains or swine strains phylogenetically closely related to the humans strains used in the HI test in this study have been affecting the swine population since 2002.

Assessment of a rapid immunochromatographic assay for the detection of avian influenza viruses

Rapid spreading of the low pathogenic avian influenza virus [AIV] caused by the H9N2 subtype and the highly pathogenic AIV caused by H5N 1 have caused serious economic losses in the poultry industries of Asia. Therefore, the early detection of AIVs is crucial for the control of the disease. In the present study, the applicability of a rapid immunochromatographic [RIC] assay, which specifically detected type A antigens of AIVs, was evaluated. This assay detected H9N2 viruses at 10[3.2] ELD[50]/ml and H5, H7 and H9 antigens at 128 HA titers, but did not react with other respiratory viruses. The assessment of cloacal swab samples prepared from 1 to 10 d post-inoculation [PI] revealed that the first positive samples were detectable on day 2 and 3 PI, and the last positive samples were detectable on day 10 and 9 PI, by the virus isolation [VI] and RIC assays, respectively. Collectively, the relative specificity, sensitivity, positive predictive value, negative predictive value, accuracy and correlation rate of the RIC and VI assays, were 100%, 71.5%, 100%, 78.5%, 0.86, and 0.98, respectively. There was also a good correlation [K> 0.81] between the results of the haemagglutination [HI], VI and RIC assays of cloacal/tracheal swab samples that were obtained from broiler flocks involved with viral respiratory diseases. Overall, RIC showed a low sensitivity and high specificity for the rapid diagnosis of H9N2 isolates in both experimental and clinical infections

Evaluation of a competitive ELISA for antibody detection against avian influenza virus

Active serologic surveillance is necessary to control the spread of the avian influenza virus (AIV). In this study, we evaluated a commercially-available cELISA in terms of its ability to detect AIV antibodies in the sera of 3,358 animals from twelve species. cELISA detected antibodies against reference H1- through H15-subtype AIV strains without cross reactivity. Furthermore, the cELISA was able to detect antibodies produced following a challenge of the AIV H9N2 subtype in chickens, or following vaccination of the AIV H9 or H5 subtypes in chickens, ducks and geese. Next, we tested the sensitivity and specificity of the cELISA with sera from twelve different animal species, and compared these results with those obtained by the hemagglutination-inhibition (HI) test, the "gold standard" in AIV sera surveillance, a second commercially-available cELISA (IZS ELISA), or the agar gel precipitation (AGP) test. Compared with the HI test, the sensitivities and specificities of cELISA were 95% and 96% in chicken, 86% and 88% in duck, 97% and 100% in turkey, 100% and 87% in goose, and 91% and 97% in swine, respectively. The sensitivities and specificities of the cELISA in this study were higher than those of IZS ELISA for the duck, turkey, goose, and grey partridge sera samples. The results of AGP test against duck and turkey sera also showed significant correlation with the results of cELISA (R-value >0.9). In terms of flock sensitivity, the cELISA correlated better with the HI test than with commercially-available indirect ELISAs, with 100% flock sensitivity.

Eventos adversos da vacina contra influenza em uma amostra de idosos de Porto Alegre/RS / Adverse effects of the influenza vaccine in elderly patients

Introdução: Há poucos dados sistematizados sobre eventos adversos da vacina contra influenza no Brasil. Objetivos: Estimar a freqüência de eventos adversos da vacina contra influenza, além de analisar queixas pós-vacinais na população-alvo da campanha. Materiais e métodos: Coorte contemporânea montada com 240 pacientes durante a Campanha Nacional de Vacinação do Idoso, em Porto Alegre. A coleta dos dados iniciou durante a vacinação e foi concluída depois de decorridos 15 dias da vacinação. As variáveis foram inicialmente analisadas com estatística descritiva. A associação bivariada entre variáveis qualitativas foi analisada pelo teste do qui-quadrado e com variáveis quantitativas, através do teste t de Student. Uma análise multivariada por meio de regressão logística foi realizada para testar a associação de pelo menos um efeito adverso da vacina com sexo, idade e presença de morbidades prévias. Foi adotado intervalo de confiança de 95%. Resultados: De 240 idosos, 22,08% (n=53) referiram pelo menos um sintoma pós-vacinal. Dos 53 idosos que apresentaram eventos adversos, 10,80% relataram apenas um sintoma, seguido de 5,40% com dois ou mais sintomas. A dor no local da injeção foi evento mais freqüente (12,50%), seguido de sintomas respiratórios (6,66%). Conclusões: A aná- lise multivariada não encontrou associação de efeitos adversos com as variáveis sexo, idade, trabalho, aposentadoria, morbidades pré-existentes e serviço de saúde. A vacina contra a gripe se mostrou pouco reatogênica quando aplicada em idosos (AU)

Background: Influenza immunization has been recommended for mature individuals over sixty-years old. At this time the unfavorable endorsements of the vaccine and the lack of documentation in the medical field in Brazil is changing. Purpose: The purpose of this survey was to identify and document various complaints by the elder patients after taking the vaccine. Methods: The survey was conducted by the Community Health Center Jardim Leopoldina in Porto Alegre, Brasil where we tested a total of two-hundred and forty (240) elderly patients, age 60 and above. Adverse events and complaints of influenza immunization were assessed. Statistical analyses admitted a confidence level of 95%, p < 0.05. Results: Fifty-three patients (22.08%) reported at least one occurrence after vaccine. Twenty-five patients (10.80%) had one incident; thirteen patients (5.40%) had two or more events. The two most common and frequent complaints were: localized pain (N=30 or 12.5%) & Upper respiratory illness (n=16 or 6.66%). Conclusions: It is our findings that gender, age, performance, type of work the patient does, & health condition were not related to the results. The influenza vaccine was well-tolerated by the patients over sixty with no vaccine associated to severe adverse effects (AU)

Immunogenicity and tolerability of inactivated flu vaccine In high risk and healthy children / Inmunogenicidad y tolerancia de la vacuna inactivada anti-influenza en niños en alto riesgo y en controles sanos

We conducted this open study to evaluate the immunogenicity and safety of the inactivated influenza vaccine, Imovax Gripe® in 154 children between 6 and 36 months of age at high risk of influenza- related complications, and in a reference group of 64 healthy children. The study was conducted over two flu seasons, in which the vaccine contained the same A strains but different B strains. The results for the A/H3N2 and A/H1N1 strains from the two flu seasons were pooled, but those for the B strains were not. Anti-hemagglutinin (HA) antibody titers were determined before, and one month after each vaccination, and safety was evaluated based on diary card reporting any adverse event observed, either included or not in the list of "solicited events". Within each group of vaccines, the seroconversion rates, seroprotection rates, and ratio of post- to prevaccination geometric mean titers (GMTR) for the A/H3N2 and the A/H1N1 strains fulfilled all requirements of the criteria of the European Union Committee for Proprietary Medicinal Products (CPMP). The immune responses in high-risk and in healthy children were similar, and consistent with those observed in previous studies conducted in healthy children. The vaccine was equally well tolerated by all study groups. Reactogenicity was low and similar in both high-risk and healthy children. Overall from 9.5% to 15.4% of at-risk children and 12% of healthy children reported a solicited local reaction; 23.0 to 28.8% of high-risk and 25.3% of healthy children reported a solicited systemic reaction. The study results provide support for vaccination of children at high-risk of influenza related complications.

Se realizó un estudio clínico abierto para evaluar la inmunogenícidad y la seguridad de la vacuna inactivada anti-influenza, Imovax Gripe®, en 154 niños entre 6 y 36 meses de edad con alto riesgo de complicaciones ligadas a la influenza, y en un grupo de referencia de 64 niños sanos. El estudio fue conducido en dos temporadas de gripe, durante las cuales la vacuna utilizada contenia las mismas cepas A pero diferentes cepas B. Los resultados para las cepas A/H3N2 y A/H1N1 de las dos temporadas de gripe fueron combinados ( pool de datos), pero no los de las cepas B. Los títulos de anticuerpos anti-hemaglutinina (HA) fueron determinados inmediatamente antes y un mes despues de cada vacunación, y la seguridad o tolerancia fue evaluada según la información de efectos adversos notificados, en cartillas para llenado diario, que incluían todos los eventos, figuraran o no en la lista de los "eventos solicitados". En cada grupo, las tasas de seroconversion y de seroprotección, y la razón de la media geométrica de títulos post-/ pre-vacunación (GMTR) para las cepas A/H3N2 y A/H1N1 cumplieron con todos los requisitos del Comité de Especialidades Farmacéuticas (CPMP) de la Unión Europea. Las respuestas inmunes fueron similares en los niños con alto riesgo y en los sanos, y consistentes con los resultados observados en los estudios anteriores en los niños sanos. La vacuna fue bien tolerada y la reactogenicidad fue baja y similar en los dos grupos de niños estudiados. Las reacciones locales listadas en la solicitud, fueron observadas en el 9.5 a 15.4% y en el 12% de niños con alto riego y sanos respectivamente; mientras que los síntomas sistémicos solicitados fueron observados en el 23.0 a 28.8% y el 25.3% de niños respectivamente. Los resultados de este estudio proveen informatión adicional a favor de la vacunación de niños con alto riesgo de complicaciones relacionadas con influenza.

Abnormal humoral immune response to influenza vaccination in pediatric type-1 human immunodeficiency virus infected patients receiving highly active antiretroviral therapy

Given that highly active antiretroviral therapy (HAART) has been demonstrated useful to restore immune competence in type-1 human immunodeficiency virus (HIV-1)-infected subjects, we evaluated the specific antibody response to influenza vaccine in a cohort of HIV-1-infected children on HAART so as to analyze the quality of this immune response in patients under antiretroviral therapy. Sixteen HIV-1-infected children and 10 HIV-1 seronegative controls were immunized with a commercially available trivalent inactivated influenza vaccine containing the strains A/H1N1, A/H3N2, and B. Serum hemagglutinin inhibition (HI) antibody titers were determined for the three viral strains at the time of vaccination and 1 month later. Immunization induced a significantly increased humoral response against the three influenza virus strains in controls, and only against A/H3N2 in HIV-1-infected children. The comparison of post-vaccination HI titers between HIV-1+ patients and HIV-1 negative controls showed significantly higher HI titers against the three strains in controls. In addition, post vaccination protective HI titers (defined as equal to or higher than 1:40) against the strains A/H3N2 and B were observed in a lower proportion of HIV-1+ children than in controls, while a similar proportion of individuals from each group achieved protective HI titers against the A/H1N1 strain. The CD4+ T cell count, CD4/CD8 T cells ratio, and serum viral load were not affected by influenza virus vaccination when pre- vs post-vaccination values were compared. These findings suggest that despite the fact that HAART is efficient in controlling HIV-1 replication and in increasing CD4+ T cell count in HIV-1-infected children, restoration of immune competence and response to cognate antigens remain incomplete, indicating that additional therapeutic strategies are required to achieve a full reconstitution of immune functions.

Risk factors for poor immune response to influenza vaccination in elderly people

Influenza vaccination of elderly people is efficacious and cost effective for the prevention of influenza and its complications. Some studies have pointed out low immunogenicity in this group. Health status has been poorly investigated as a risk factor that may influence the immune response to influenza vaccine. We established an immunization response study of a highly-matched elderly population in a nursing home. One-hundred-twenty subjects of Ashkenazian origin had their vaccine-induced antibody response assessed. Good response was obtained in 30.8 percent (37/120), and 31.7 percent (38/120) did not react. A lack of good response was found to be associated with dementia (P=0.016) in a multivariate analysis. In addition to dementia, malnutrition was frequently observed among poor responders, suggesting that these factors should be considered in vaccination studies. Chemoprophylaxis in addition to vaccination for elderly presenting dementia should be considered, particularly for those people living nursing homes.

La prevención de la influenza: recomendaciones para la temporada de 2005-2006 / Preventing influenza: recommendations for the 2005-2006 season

Influenza is a serious health problem worldwide due to the epidemics and pandemics that it periodically causes. The Advisory Committee on Immunization Practices (ACIP) of the United States of America recently published updated recommendations for influenza prevention and control for the 2005-2006 season. Many of these guidelines are of interest to the countries of the Region of the Americas, particularly those related to vaccination, which is the mainstay for preventing and controlling this disease. Various changes have been made in the recommendations that were published in 2004. First, the ACIP recommends vaccination against influenza for persons with any condition (e.g., cognitive dysfunction, spinal cord injury, seizure disorder, or other neuromuscular disorder) that can compromise respiratory function or make eliminating respiratory secretions difficult or that can increase the risk for aspiration. Second, the ACIP strongly recommends that all health care workers be vaccinated against influenza annually and encourages facilities that employ health care workers to vaccinate them by using approaches that maximize immunization rates. Third, the ACIP encourages the use of both available vaccines (inactivated and live, attenuated influenza vaccine (LAIV)) for eligible persons every influenza season, especially persons in recommended target groups. When inactivated virus vaccine is in short supply, the use of LAIV is especially encouraged, if feasible, for eligible persons (including health care workers) because such use might considerably increase the availability of inactivated virus vaccine for persons in high-risk groups. Fourth, the 2005-06 trivalent vaccine virus strains are A/California/7/2004 (H3N2)-like, A/New Caledonia/20/99 (H1N1)-like, and B/Shanghai/361/2002-like antigens. For the A/California/7/2004 (H3N2)-like antigen, manufacturers may use the antigenically equivalent A/ New York/55/2004 virus, and for the B/Shanghai/361/2002-like antigen, manufacturers may use the antigenically equivalent B/Jilin/20/2003 virus or B/Jiangsu/10/2003 virus.

A pilot study of seroprevalence of influenza virus type A in Vellore, south India.

BACKGROUND & OBJECTIVES: Influenza virus type A is active in many regions of the world. However, information from many parts of India is sparse. Hence we carried out a serological study on the prevalence of antibodies to influenza virus type A in Vellore, south India. METHODS: Antibodies to influenza virus type A (H1N1 and H3N2) were detected using a haemagglutination inhibition (HI) test. A total of 186 individuals comprising healthy blood donors and laboratory workers were tested. RESULTS: The titres ranged from < 20-2580, with a high geometric mean titre (GMT) of 200 for H3N2 and < 20-1280 with a GMT of 74 for H1N1 serotype of influenza virus type A. Among the 186 serum samples tested, 175 (94.04%) were positive for H1N1 and 185 (99.5%) for H3N2 with a titre > 20. INTERPRETATION & CONCLUSION: The prevalence of elevated level of antibodies in the individuals indicates a high exposure to the influenza A virus in our population with a seropositive status in 99.5 per cent of the individuals tested. Virus surveillance needs to be instituted in different parts of the country to monitor the activity of these viruses.

Estudio antigenico de cepas de influenza A (H3N2) circulantes en la Argentina Y su relacion con las cepas vacunales / Antigenic relationship between influenza A (H3N2) strains circulating in Argentina and vaccine strains

Debido a que los brotes anuales de influenza en Argentina ocurren comúnmente entre mayo y septiembre, la vacuna producida en el hemisferio norte para ser administrada en el mismo durante los meses de octubre y noviembre podría encontrarse desfasada para nuestro país. Con los fines de determinar si las cepas circulares en Argentina se encuentran relacionadas cercanamente desde el punto de vista antigénico con las cepas que integran las vacunas administradas, se las comparó con los virus de influenza A (H3N2) aislados entre mayo de 1994 y diciembre de 1997. Los especímenes clínicos (9866) utilizados fueron aspirados nasofaríngeos de niños hospitalizados con infección respiratoria aguda baja e hisopados nasofaríngeos de adultos con síndrome gripal. El diagnóstico de laboratorio inicial fue realizado por inmunofluorescencia, seguido por el intento de aislamiento viral en células MDCK. Se detectaron 242 virus de influenza A que fueron subtipificados antigénicamente pro inhibición de la hemaglutación (IHA) con el equipo de reactivos para influenza distribuido por la OMS. Una fracción de los virus detectados fue analizada antigénicamente por el Centro Colaborador de la OMS, Una facción de los virus detectados fue analizada antigénicamente por el Centro Colaborador de la OMS, que funciona en el CDC de Atlanta, Estados Unidos. Los virus de Influenza A (H3N2) caracterizados que circularon en Argentina na durante los últimos 4 años se correlacionaron parcialmente con los antígenos presentes en las vacunas administradas entre 1994 y 1997. Algunos años, estas variantes antigénicas circularon tardíamente (octubre de 1994 y de 1997). Las mismas iniciaron los brotes epidémicos de los años siguientes, fueron las prevalentes durante los mismos y estuvieron presentes dos años después en la fórmula vacunal administrada en el hemisferio sur. Los resultados de la IHA de nuestros aislamientos mostraron una elevada respuesta específica con los antisueros homólogos y una menos específica (16-64 veces menor) con los antidueros producidos contra las cepas vacunales. Esto nos demuestra la necesidad de intensificar la vigilância de influenza desde el laboratorio para tratar de formular la vacuna más apropiada.

Survival and quality of life in HIV-positive patients treated with a polyantigenic immunomodulator

A polyantigenic immunomodulator (PAI), previously known as polyantigenic vaccine, which consists of a mixture of antigens of inactivated bacteria with antigens of influenza virus in a peanut-oil-arlacel-A-aluminium monoesterate emulsion, increased tumor resistance and induced tumor regression in tumor bearing mice. This report presents clinical and laboratory data that demonstrate the effect of PAI in long term prolongation of disease free state in HIV positive patients. A total of 40 patients, 35 males and 5 females, with a mean age of 41.1 +/- 10.5 years, ranging from 28 to 68 years, HIV positive by (ELISA and Western Blot), with no restriction on the CD4 + T lymphocytes counts, were included in this open study. The PAI regimen was one subcutaneous injection per week for patients with < 400 CD4 + lymphocytes and one monthly injection for patients with CD4 + count > 400. All patients were monitored at different intervals for lymphocyte counts, clinical condition and treatment toxicity. After a follow up of eight years 81 percent of the patients were alive and 47 percent were free of disease. In patients without AIDS, the weight was 153.9 +/- 28 pounds pre-PAI and 164.6 +/- 27 (P = 1.2 x 10(-4); the CD4 + lymphocyte count was 795 +/- 421 pre-PAI and 585 +/- 279 post PAI (P = 0.08). In patients alive with AIDS, the weight was 159.5 +/- 32 pre-PAI and 163.9 +/- 32 pounds post-PAI (P = 0.8); the CD4 + lymphocyte counts was 491 +/- 255 pre-PAI and 298 +/- 142 post-PAI (P = 0.08); and five AIDS-related infections occurred in five patients. In patients who died the weight was 157.7 +/- 23 pre and 146.8 +/- 30 post (P = 0.10); and the CD4 count was 340.7 +/- 149 pre and 103.4 +/- 88 post (P = 0.0057). All died with infection. No toxicity with the use of PAI was reported. PAI improves disease free survival and quality of life in HIV + patients

Influenza eqüina: avaliaçäo da resposta imune humoral, através das reaçöes de inibiçäo da hemaglutinaçäo e de hemólise radial simples, em soro de animais vacinados com vacina comercial e experimental / Equine influenza: evaluation of the humoral immune response through the hemagglutination inhibition and single radial haemolysis, in vaccinated horses with commercial and experimental vaccines

Foram avaliadas, através de testes de inibiçäo da hemaglutinaçäo (HI) e da hemólise radial simples (HRS), as respostas de anticorpos contra influenza em 4 lotes de eqüinos adultos. O grupo do lote 01 recebeu a imunizaçäo com 2 doses de vacina contra influenza, preparada experimentalmente no Instituto Butantan. Nos lotes 02 e 03, regularmente imunizados contra a influenza, foram administradas doses de reforço anual com a vacina comercial e com a vacina experimental, respectivamente. O lote 04 foi o grupo controle da avaliaçäo. Os resultados dos testes demonstraram que as médias de títulos de HRS e IH do lote 01 apresentaram diferenças ao nível de p < 0,001, com significante aumento das médias de títulos detectados nos soros após a 2a. imunizaçäo. Näo foram observadas diferenças significantes entre as médias de títulos de anticorpos em soros obtidos antes e após a dose de reforço anual dos eqüinos dos lotes 02 e 03, atribuindo-se a persistência de nível de anticorpos protetores mantida após 1 ano da imunizaçäo regular com vacina comercial. A conversäo sorológica dos eqüinos do lote 01, à persistência dos títulos de anticorpos nos eqüinos dos lotes 02 e 03 e, ainda, os baixos títulos de anticorpos verificados nos eqüinos näo vacinados do lote 04 comprovam o resultado da resposta sorológica das duas vacinas, a experimental e a comercial, avaliadas neste trabalho

The role of antigenically different virus neuraminidases as structures implicated in receptor-binding processes

Influenza A viruses exhibit segmented nucleic acid coding for eight different proteins, two of them as glycoproteins exposed on their lipoprotein envelopes, hemagglutinin (HA) and neuraminidase (NA). Hemagglutinin exhibits recptor-binding activity while neuraminidase develps sialidase cleavage activity which acts on cell receptors. Influenza A strains responsible for human, avian, equine and porcine respiratory infections all over the world present antigenically different hemagglutinin (H1 to H14) and neutraminidase (N1 to N9) structures on their surface. The objective of the present investigation was study the role of N2, N8 and N9, anti-genically diverse neuraminidase structures of human (N2) and animal (N8 and N9) influenza viruses, in the receptor-binding process. REceptor-binding activity of N2 and N8 was anlyzed by crossed tests using H3N2 and H3N8 antisera and the hemagglutination inhibition test as a model. Hemangglutinating activity of antigenically different N2 and N8 structures was demonstrable and was inhibited by homologous antisera (N2-H3N2, N8-H3N8) but not by heterologous antisera (N2-H3-N8,N8-H3-N2). This previously demonstrated N9 hemagglutinating activity was analysed for receptor-binding specificity using hemagglutination test and NeuAc alpha2,3Gal and NeuAc alpha2,6Gal derivatized erythrocytes. This highly purified N9 strain was obtained from a virus strain isolated from terns by Dr. Peter Colman (CSIRO Division of Biomolecular Engineering, Parkville, Victoria, Australia)...

Single radial immunodiffusion potency test for standardization of indigenous equine influenza vaccine.

Single radial immunodiffusion (SRD) assays were used for measuring the haemagglutinin antigen contents of equine influenza vaccine prepared from an Indian virus isolate. A/Equine-2/Ludhiana/1/87 (H3N8). Five different preparations of the vaccine were standardized by SRD to prepare 913 doses, each containing 20 micrograms HA/ml-1 dose-1. This test also showed influenza virus subtype specificity as no cross reaction was observed between subtype 1 (H7N7) and subtype 2 (H3N8) viruses.