Prolongada persistência do vírus da gripe em hamsters inoculados por vias parenterais e nasal

As experiências relatadas no presente trabalho visaram observar a persistência do vírus da gripe em hamsters inoculados pelas vias subcutânea, peritoneal e nasal. Usaram-se 53 hamsters na verificação da persistência do vírus nos seus organismos a qual atingiu até um ano e cinco meses, pelo menos, numa das séries de experiências. A outra parte do trabalho consistiu em verificar a passagem do vírus, em série, de hamster a hamster. Observamo-la até o máximo de nove vezes, o que foi excepcional, notando-se passagens, na série, com resultados negativos intercalados. Para esta última parte forma usados 91 hamsters, perfazendo o total de 144 em todas as experiências realizadas.

Persistência do vírus da gripe no cérebro de Hamsters inoculados por via intracerebral

Visou-se, no presente trabalho, observar a persistência do vírus da gripe em hamsters inoculados por via intracerebral. Foram empregados 10 desses animais, assinalando-se a presença do vírus, no tecido nervoso, até, pelo menos, 10 meses e 9 dias após a inoculação.

Presença do vírus da gripe no sangue e órgãos de animais inoculados por via intracardíaca

Executou-se o presente trabalho com a finalidade de isolar o vírus da gripe do sangue e de órgãos de camundongos inoculados por via intracardíaca. A observação foi feita com intervalos de 3 a 120 dias após à inoculação. O isolamento do vírus apresentou algumas variações, conforme o tempo decorrido e o material examinado. A presente publicação foi feita em prosseguimento ás anteriores (1 e 2) que tratam da persistência do vírus da gripe em animais inoculados. Neste caso, inocularam-se camundongos brancos por via intracardíaca, ainda não experimentada por nós.

A reação de fixação do complemento na tipificação de vírus da gripe isolados no Rio de Janeiro

O autor estudou, pela reação de fixação do complemento, amostras de vírus da gripe isoladas no Rio de janeiro, durante a epidemia de 1973. Preparou imunesoros em hamsters pela inoculação do líquido alantóide de embriões de galinha infectados. o antígeno solúvel foi preparado com líquido obtido da mesma proveniência. As reações foram positivas, em grau variável, com as amostras clássicas PR8, FM1 e Ásia dos subtipos A0,A1 e A2 e as mais recentes A2/Hong Kong/68 e A2/England/72 e negativa com o anticorpo B/Mass/66. Para as duas variantes do subtipo A2, acima assinaladas e para as 7 amostras isoladas o comportamento foi praticamente o mesmo, não deixando de ser uma reação tipo específica se encararmos, também, as reações obtidas com as demais variantes do tipo A.

Demonstração por imunofluorescência direta de antígenos do vírus da febre amarela em tecido hepático pré-tratado com tripsina

Neste trabalho descreve-se uma prova de imunofluorescência direta (IFD), com o mesmo material de fragmentos de tecido hepático, fixados em formol, obtidos de casos suspeitos de infecção por febre amarela e utilizados para a histopatologia; um conjugado fluorescente foi preparado com soro de macacos sem anticorpos para hepatite A e B, previamente inoculados com a amostra vacinal 17D de febre amarela. São considerados positivos para febre amarela por esta técnica os casos que apresentaram fluoresc~encia citoplasmática de seus hepatócitos, após um tratamento prévio do tecido com tripsina a 0,1% por 2 horas a 37°C. Em 76 casos estudados, 33 considerados positivos e 34 considerados negativos na histopatologia apresentaram resultados concordantes com a reação de imunofluorescência, de 9 casos com diagnóstico duvidoso, 8 foram negativos e 1 apresentou-se positivo na prova da IFD. Materiais obtidos de casos de hepatite e de tecidos hepáticos normais foram sempre negativos na IFD para febre amarela; utilizou-se como controle positivo, células em cultura de linhagem Vero, infectadas com a mesma amostra 17D, as quais mostraram intensa fluorescência específica. A técnica descrita mostrou-se de utilidade, como uma reação específica, em complemento aos estudos patológicos, em especial no diagnóstico de casos duvidosos, com a vantagem de utilizar o mesmo material previamente fixado em formol, recebido rotineiramente pelos laboratórios responsáveis pelo diagnóstico de febre amarela no país.

Influenza surviellance in Rio de Janeiro between 1980-1981: a virological and serological study

Laboratory surveillance of influenza has shown a low virus activity in Rio de Janeiro during 1980 and 1981. A few influenza A (H3N2) viruses were isolated in both years during the winter months. Serological investigations showed that this subtype has circulated mostly among children under 10 years of age. No H1N1 virus was isolated but an increase in the proportion of adults with antibody to his virus was noted in sera collected in 1981. Influenza B virus was isolated from children in the spring of 1981 and again an increase was noted in the proportion of adults with antibody to this virus.

The feasibility of forecasting influenza epidemics in Cuba

A large influenza epidemic took place in Havana during the winter of 1988. The epidemiologic surveillance unit of the Pedro Kouri Institute of Tropical Medicine detected the begining of the epidemic wave. The Rvachev-Baroyan mathematical model of the geographic spread of an epidemic was used to forecast this epidemic under routine conditions of the public health system. The expected number of individuals who would attend outpatient services, because of influenza-like illness, was calculated and communicated to the health authorities within enough time to permit the introduction of available control measures. The approximate date of the epidemic peak, the daily expected number of individuals attending medical services, and the approximate time of the end of the epidemic wave were estimated. The prediction error was 12%. The model was sufficienty accurate to warrant its use as a pratical forecasting tool in the Cuban public health system.

Characterization of the hemagglutinin receptor specificity and neuraminidase substrate specificity of clinical isolates of human influenza A viruses

Six clinical isolates of influenza A viruses were examined for hemagglutinin receptor specificity and neuraminidase substrate specificity. All of the viral isolates minimally passaged in mammalian cells demonstrated preferential agglutination of human erythrocytes enzymatically modified to contain NeuAc alpha 2,6Gal sequences, with no agglutination of cells bearing NeuAc alpha 2,3Gal sequences. This finding is consistent with the hemagglutination receptor specificity previously demonstrated for laboratory strains of influenza A viruses. The neuraminidase substrate specificities of the clinical isolates examined were also identical to that described for the N2 neuraminidase of recent laboratory strains of human influenza viruses. The H3N2 viruses all displayed the ability to release sialic acid from both alpha 2, 3 and alpha 2, 6 linkages. In addition, two clinical isolates of H1N1 viruses also demonstrated this dual neuraminidase substrate specificity, a characteristic which has not been previously described for the N1 neuraminidase. These results demonstrate that complementary hemagglutinin and neuraminidase specificities are found in recent isolates of both H1N1 and H3N2 influenza viruses.

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.

The epidemiology and antigenic characterization of influenza viruses isolated in Curitiba, South Brazil

Several studies conducted all over the world have reported that the influenza virus is associated with great morbidity and mortality rates. In this study, we analyzed the incidence of the influenza virus between 2000 and 2003 in Curitiba. We studied 1621 samples obtained from outpatients and hospitalized patients of both sexes and all ages. The study was conducted at the local primary care health units (outpatients) and at the tertiary care unit (hospitalized) of the General Hospital of the Federal University in the state of Paraná, Brazil. Nasopharyngeal aspirates and, eventually, bronchoalveolar lavage were assayed for the presence of viral antigens, either by indirect immunofluorescence or cell culture. Of the samples studied, 135 (8.3%) were positive for influenza virus, and of those, 103 (76.3%) were positive for type A and 32 (23.7%) for type B. Additionally, positive samples were analyzed by reverse transcription followed by polymerase chain reaction and subtypes H1 and H3 were identified from this group. A high incidence of positive samples was observed mainly in the months with lower temperatures. Furthermore, outpatients showed a higher incidence of influenza viruses than hospitalized patients.

The risk of acquiring the new influenza A(H1N1) for Brazilian travelers to Chile, Argentina and the USA

We estimate the risk of acquiring the new influenza A(H1N1) for Brazilian travelers to Chile, Argentina and the USA. This is done by a mathematical model that quantifies the intensity of transmission of the new virus in those countries and the probability that one individual has of acquiring the influenza depending on the date of arrival and time spent in the area. The maximum estimated risk reached 7.5 cases per 10,000 visitors to Chile, 17 cases per 10,000 travelers to Argentina and 23 cases per 10,000 travelers to the USA. The estimated number of imported cases until 27 July is 57 ± 9 from Chile, 136 ± 27 from the USA and 301 ± 21 from Argentina, which are in accord with the official figures. Estimating the number of imported cases was particularly important for the moment of the disease introduction into this country, but it will certainly be important again as a tool to calculate the number of future imported cases from northern countries in our next inter-epidemic season, were imported cases can constitute again the majority of the new influenza burden to the Brazilian health services.

Sequence analysis of the 2009 pandemic influenza A H1N1 virus haemagglutinin gene from 2009-2010 Brazilian clinical samples

In this paper, we analysed the haemagglutinin (HA) gene identified by polymerase chain reaction from 90 influenza A H1N1 virus strains that circulated in Brazil from April 2009-June 2010. A World Health Organization sequencing protocol allowed us to identify amino acid mutations in the HA protein at positions S220T (71%), D239G/N/S (20%), Y247H (4.5%), E252K (3.3%), M274V (2.2%), Q310H (26.7%) and E391K (12%). A fatal outcome was associated with the D239G mutation (p < 0.0001). Brazilian HA genetic diversity, in comparison to a reference strain from California, highlights the role of influenza virus surveillance for study of viral evolution, in addition to monitoring the spread of the virus worldwide.

VaxcineTM: an oil-based adjuvant for influenza vaccines

Vaccination is the method of choice for the prevention of influenza infection. However, the quantity of the antigen available, especially in the case of pandemics, often fails to meet the global demand. However, improved adjuvants can overcome this problem. Preliminary results obtained in this study revealed that one year after a single subcutaneous immunisation with influenza A H3N2 virus in an oil-based carrier, VaxcineTM, outbreed mice produced a high immunoglobulin G response that lasted for up to one year and exhibited less variation in titre compared with the response of the control group treated with alum. The haemagglutination-inhibition titres induced by VaxcineTM were also higher than those generated by alum. These data indicate that VaxcineTM is a good adjuvant candidate for seasonal influenza vaccines.

Comparison of adverse events following immunization with pandemic influenza A (H1N1)pdm09 vaccine with or without adjuvant among health professionals in Rio de Janeiro, Brazil

A vaccination campaign against pandemic influenza A (H1N1)pdm09 was held in Brazil in March 2010, using two types of monovalent split virus vaccines: an AS03-adjuvanted vaccine and a non-adjuvanted vaccine. We compared the reactogenicity of the vaccines in health professionals from a Clinical Research Institute in Rio de Janeiro, Brazil and there were no serious adverse events following immunization (AEFI) among the 494 subjects evaluated. The prevalence of any AEFI was higher in the AS03-adjuvanted vaccine at 2 h and 24 h post-vaccination [preva-lence ratio (PR): 2.05, confidence interval (CI) 95%: 1.55-2.71, PR: 3.42, CI 95%: 2.62-4.48, respectively]; however, there was no difference between the vaccines in the assessments conducted at seven and 21 days post-vaccination. The group receiving the AS03 post-adjuvanted vaccine had a higher frequency of local reactions at 2 h (PR: 3.01, CI 95%: 2.12-4.29), 24 h (PR: 4.57, CI 95%: 3.29-6.37) and seven days (PR: 6.05, CI 95%: 2.98-12.28) post-vaccination. We concluded that the two types of vaccines caused no serious AEFI in the studied population and the adjuvanted vaccine was more reactogenic, particularly in the 24 h following vaccination. This behaviour must be confirmed and better characterised by longitudinal studies in the general population.

Oseltamivir-resistant influenza A(H1N1)pdm09 virus in southern Brazil

The neuraminidase (NA) genes of A(H1N1)pdm09 influenza virus isolates from 306 infected patients were analysed. The circulation of oseltamivir-resistant viruses in Brazil has not been reported previously. Clinical samples were collected in the state of Rio Grande do Sul (RS) from 2009-2011 and two NA inhibitor-resistant mutants were identified, one in 2009 (H275Y) and the other in 2011 (S247N). This study revealed a low prevalence of resistant viruses (0.8%) with no spread of the resistant mutants throughout RS.