Immune activation alters cellular and humoral responses to yellow fever 17D vaccine.

Background. Defining the parameters that modulate vaccine responses in African populations will be imperative to design effective vaccines for protection against HIV, malaria, tuberculosis, and dengue virus infections. This study aimed to evaluate the contribution of the patient-specific immune microenvironment to the response to the licensed yellow fever vaccine 17D (YF-17D) in an African cohort. Methods. We compared responses to YF-17D in 50 volunteers in Entebbe, Uganda, and 50 volunteers in Lausanne, Switzerland. We measured the CD8+ T cell and B cell responses induced by YF-17D and correlated them with immune parameters analyzed by flow cytometry prior to vaccination. Results. We showed that YF-17D-induced CD8+ T cell and B cell responses were substantially lower in immunized individuals from Entebbe compared with immunized individuals from Lausanne. The impaired vaccine response in the Entebbe cohort associated with reduced YF-17D replication. Prior to vaccination, we observed higher frequencies of exhausted and activated NK cells, differentiated T and B cell subsets and proinflammatory monocytes, suggesting an activated immune microenvironment in the Entebbe volunteers. Interestingly, activation of CD8+ T cells and B cells as well as proinflammatory monocytes at baseline negatively correlated with YF-17D-neutralizing antibody titers after vaccination. Additionally, memory T and B cell responses in preimmunized volunteers exhibited reduced persistence in the Entebbe cohort but were boosted by a second vaccination. Conclusion. Together, these results demonstrate that an activated immune microenvironment prior to vaccination impedes efficacy of the YF-17D vaccine in an African cohort and suggest that vaccine regimens may need to be boosted in African populations to achieve efficient immunity. Trial registration. Registration is not required for observational studies. Funding. This study was funded by Canada's Global Health Research Initiative, Defense Threat Reduction Agency, National Institute of Allergy and Infectious Diseases, Bill & Melinda Gates Foundation, and United States Agency for International Development.

Immunogenicity and safety of yellow fever vaccination for 102 HIV-infected patients.

BACKGROUND: Yellow fever vaccine (17DV) has been investigated incompletely in human immunodeficiency virus (HIV)-infected patients, and adequate immunogenicity and safety are of concern in this population. METHODS: In the Swiss HIV Cohort Study, we identified 102 patients who received 17DV while they were HIV infected. We analyzed neutralization titers (NTs) after 17DV administration using the plaque reduction neutralization test. NTs of 1:>or=10 were defined as reactive, and those of 1:<10 were defined as nonreactive, which was considered to be nonprotective. The results were compared with data for HIV-uninfected individuals. Serious adverse events were defined as hospitalization or death within 6 weeks after receipt of 17DV. RESULTS: At the time of 17DV administration, the median CD4 cell count was 537 cells/mm(3) (range, 11-1730 cells/mm(3)), and the HIV RNA level was undetectable in 41 of 102 HIV-infected patients. During the first year after vaccination, fewer HIV-infected patients (65 [83%] of 78; P = .01) than HIV-uninfected patients revealed reactive NTs, and their NTs were significantly lower (P < .001) than in HIV-uninfected individuals. Eleven patients with initially reactive NTs lost these reactive NTs <or= 5 years after vaccination. Higher NTs during the first year after vaccination were associated with undetectable HIV RNA levels, increasing CD4 cell count, and female sex. We found no serious adverse events after 17DV administration among HIV-infected patients. CONCLUSION: Compared with HIV-uninfected individuals, HIV-infected patients respond to 17DV with lower reactive NTs, more often demonstrate nonprotective NTs, and may experience a more rapid decline in NTs during follow-up. Vaccination with 17DV appears to be safe in HIV-infected individuals who have high CD4 cell counts, although rate of serious adverse events of up to 3% cannot be excluded.

Variabilidade genética de Sugarcane mosaic virus, causando mosaico em milho no Brasil

O objetivo deste trabalho foi caracterizar biológica e molecularmente três isolados de Sugarcane mosaic virus (SCMV) de lavouras de milho, analisá-los filogeneticamente e discriminar polimorfismos do genoma. Plantas com sintomas de mosaico e nanismo foram coletadas em lavouras de milho, no Estado de São Paulo e no Município de Rio Verde, GO, e seus extratos foliares foram inoculados em plantas indicadoras e submetidos à análise sorológica com antissoros contra o SCMV, contra o Maize dwarf mosaic virus (MDMV) e contra o Johnsongrass mosaic virus (JGMV). Mudas de sorgo 'Rio' e 'TX 2786' apresentaram sintomas de mosaico após a inoculação dos três isolados, e o DAS-ELISA confirmou a infecção pelo SCMV. O RNA total foi extraído e usado para amplificação por transcriptase reversa seguida de reação em cadeia de polimerase (RT-PCR). Fragmentos específicos foram amplificados, submetidos à análise por polimorfismo de comprimento de fragmento de restrição (RFLP) e sequenciados. Foi possível discriminar os genótipos de SCMV isolados de milho de outros isolados brasileiros do vírus. Alinhamentos múltiplos e análises dos perfis filogenéticos corroboram esses dados e mostram diversidade nas sequências de nucleotídeos que codificam para a proteína capsidial, o que explica o agrupamento separado desses isolados e sugere sua classificação como estirpes distintas, em lugar de simples isolados geográficos.

Long-lasting stem cell-like memory CD8+ T cells with a naïve-like profile upon yellow fever vaccination.

Efficient and persisting immune memory is essential for long-term protection from infectious and malignant diseases. The yellow fever (YF) vaccine is a live attenuated virus that mediates lifelong protection, with recent studies showing that the CD8(+) T cell response is particularly robust. Yet, limited data exist regarding the long-term CD8(+) T cell response, with no studies beyond 5 years after vaccination. We investigated 41 vaccinees, spanning 0.27 to 35 years after vaccination. YF-specific CD8(+) T cells were readily detected in almost all donors (38 of 41), with frequencies decreasing with time. As previously described, effector cells dominated the response early after vaccination. We detected a population of naïve-like YF-specific CD8(+) T cells that was stably maintained for more than 25 years and was capable of self-renewal ex vivo. In-depth analyses of markers and genome-wide mRNA profiling showed that naïve-like YF-specific CD8(+) T cells in vaccinees (i) were distinct from genuine naïve cells in unvaccinated donors, (ii) resembled the recently described stem cell-like memory subset (Tscm), and (iii) among all differentiated subsets, had profiles closest to naïve cells. Our findings reveal that CD8(+) Tscm are efficiently induced by a vaccine in humans, persist for decades, and preserve a naïveness-like profile. These data support YF vaccination as an optimal mechanistic model for the study of long-lasting memory CD8(+) T cells in humans.

Transgenic passionfruit expressing RNA derived from Cowpea aphid-borne mosaic virus is resistant to passionfruit woodiness disease

Sixteen transgenic yellow passionfruit (Passiflora spp.) plants (R0) were obtained which express a non-translatable transgenic RNA corresponding to the 3' region of the NIb gene and the 5' region of the CP gene, derived from the genome of a Brazilian isolate of Cowpea aphid-borne mosaic virus (CABMV). The transgenic plants were propagated by stem cuttings and challenged by sap inoculation with isolates CABMV-MG1 and CABMV-PE1. One transgenic plant (TE5-10) was resistant to the isolate CABMV-MG1, but susceptible to CABMV-PE1. The remaining transgenic plants developed systemic symptoms, equal to non-transformed plants, when inoculated with either isolate. The absence of virus in TE5-10 plants was confirmed by indirect ELISA. Transcription analysis of the transgene demonstrated that the TE5-10 plant did not accumulate transgenic mRNA, even before inoculation. After inoculation, viral RNA was only detected in plants inoculated with CABMV-PE1. These results confirm that the transgenic plant TE5-10 is resistant to isolate CABMV-MG1, and suggest that the resistance mechanism is post-transcriptional gene silencing, which is already activated in the transgenic plants before virus inoculation.

Caracterização de um isolado do Sugarcane mosaic virus que quebra a resistência de variedades comerciais de cana-de-açúcar

Os vírus pertencentes ao subgrupo do Sugarcane mosaic virus (SCMV, gênero Potyvirus, família Potyviridae) infectam e causam mosaico em diferentes espécies botânicas da subfamília Panicoideae (família Poaceae), porém apenas o SCMV e o Sorghum mosaic virus (SrMV) infectam naturalmente cana-de-açúcar. No Brasil, a espécie SCMV parece ser o único agente causal da doença. Embora a maioria das variedades comerciais de cana-de-açúcar seja considerada resistente ou tolerante ao SCMV, relatos de incidência de mosaico em tais variedades têm ocorrido no campo. Amostras com sintomas, de diversos clones e variedades, foram coletadas em campos experimentais e comerciais de cana-de-açúcar. Dentre as variedades, a RB72-454, uma das mais plantadas no país e considerada resistente à doença, também apresentou plantas com sintomas de mosaico. As amostras foram testadas por DAS-ELISA, com anti-soros policlonais para as espécies SCMV, Johnsongrass mosaic virus (JGMV) e Maize dwarf mosaic virus (MDMV), apresentando resultados negativos. Porém, sintomas de mosaico foram observados em mudas de sorgo "Rio" e "TX2786" quando inoculadas mecanicamente com os isolados, indicando tratar-se de infecção pelo SCMV. RNA total foi extraído das folhas de cana e submetido a RT-PCR com oligonucleotídeos específicos para SCMV e SrMV. Fragmentos específicos de aproximadamente 880 pares de bases foram amplificados com os oligonucleotídeos para o SCMV, confirmando os resultados da inoculação mecânica. Os produtos de PCR foram clonados e seqüenciados. Um dos isolados de SCMV encontrado constitui uma nova estirpe, mais severa, capaz de infectar plantas da variedade RB72-454 e de outras variedades, consideradas tolerantes, no campo.

Ocorrência e variabilidade genética do Tomato severe rugose virus em tomateiro e pimentão no Estado de São Paulo

Um levantamento para avaliar a ocorrência de begomovírus nas culturas de pimentão e tomateiro no estado de São Paulo foi realizado entre janeiro/2007 e julho/2008. O DNA total de amostras de pimentão (710) e de tomateiro (103) foi extraído e a presença de begomovírus foi testada por PCR. Paralelamente, as mesmas amostras foram avaliadas por amplificação por círculo rolante (RCA) seguidas de PCR, e algumas amostras positivas analisadas por RCA-RFLP com a enzima de restrição HpaII, a fim de se conhecer a variabilidade genética dos isolados. Os resultados demonstraram que, para a técnica de PCR, 99 amostras de pimentão (13,94%) e 39 de tomateiro (37,86%) foram positivas para a presença de begomovírus, enquanto que por RCA-PCR, 333 (46,90%) de pimentão e 82 (79,61%) de tomateiro mostrando a maior sensibilidade desta técnica. Seqüências correspondentes à região 5' da capa protéica (CP) e um segmento de gene da região intergênica foram analisadas e indicaram apenas a presença da espécie Tomato severe rugose virus (ToSRV). Porém, seqüenciamento parcial de clones obtidos a partir de produto RCA de tomateiro permitiu a detecção de infecção mista de ToSRV e Tomato yellow vein streak virus (ToYVSV). Por RCA-RFLP quatro padrões de restrição foram observados para o ToSRV em pimentão, enquanto que em tomateiro observaram-se 18 padrões.Os resultados indicam maior diversidade genética dos begomovírus em tomateiro quando comparada com os de pimentão.

Ocorrência e variabilidade genética do Tomato severe rugose virus em tomateiro e pimentão no Estado de São Paulo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Variabilidade genética de Sugarcane mosaic virus, causando mosaico em milho no Brasil

O objetivo deste trabalho foi caracterizar biológica e molecularmente três isolados de Sugarcane mosaic virus (SCMV) de lavouras de milho, analisá-los filogeneticamente e discriminar polimorfismos do genoma. Plantas com sintomas de mosaico e nanismo foram coletadas em lavouras de milho, no Estado de São Paulo e no Município de Rio Verde, GO, e seus extratos foliares foram inoculados em plantas indicadoras e submetidos à análise sorológica com antissoros contra o SCMV, contra o Maize dwarf mosaic virus (MDMV) e contra o Johnsongrass mosaic virus (JGMV). Mudas de sorgo 'Rio' e 'TX 2786' apresentaram sintomas de mosaico após a inoculação dos três isolados, e o DAS-ELISA confirmou a infecção pelo SCMV. O RNA total foi extraído e usado para amplificação por transcriptase reversa seguida de reação em cadeia de polimerase (RT-PCR). Fragmentos específicos foram amplificados, submetidos à análise por polimorfismo de comprimento de fragmento de restrição (RFLP) e sequenciados. Foi possível discriminar os genótipos de SCMV isolados de milho de outros isolados brasileiros do vírus. Alinhamentos múltiplos e análises dos perfis filogenéticos corroboram esses dados e mostram diversidade nas sequências de nucleotídeos que codificam para a proteína capsidial, o que explica o agrupamento separado desses isolados e sugere sua classificação como estirpes distintas, em lugar de simples isolados geográficos.

Caracterização de um isolado do Sugarcane mosaic virus que quebra a resistência de variedades comerciais de cana-de-açúcar

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Hepatocyte lesions and cellular immune response in yellow fever infection

The study of the in-situ cellular immune response is very important for the understanding of different liver infections. In the present study, 53 liver samples obtained by viscerotomy from patients who died during the course of jungle yellow fever were analyzed. The diagnosis was confirmed by serology, viral isolation and virus-specific immunohistochemistry. The specimens were analyzed by immunohistochemistry using specific antibodies for apoptosis, CD45RO, CD4, CD8, CD20, S100, CD57 and CD68. Quantitative analysis of the labeling pattern showed a clear predominance of the different phenotypes in the portal tract and midzone region of the acini. There was a predominance of T CD4+ lymphocytes, accompanied by the presence of T CD8+ lymphocytes, natural killer cells (CD57), macrophages and antigen-presenting cells (S100). The disproportion between the intensity of inflammation and the degree of hepatic injury was probably due to the intense apoptotic component, which classically does not induce an inflammatory response. The present study demonstrates that, despite the disproportion between injury and inflammation, the cellular immune response plays an important role in the pathogenesis of the hepatocytic injury observed in yellow fever, probably as a result of cytolytic actions through mechanisms involving MHC II and the activation of Fas receptors and granzymes/perforins. (C) 2006 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.

Ocorrência de begomovírus de plantas de pimentão no Estado de São Paulo e comportamento de genótipos de Capsicum spp. ao tomato severe rugose virus e a Bemisia tabaci meam1

Pós-graduação em Agronomia (Proteção de Plantas) - FCA

Epidemiologia do Cowpea aphid borne mosaic virus (CABMV) em maracujazeiros na região produtora da Alta Paulista, SP

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Immunogenicity and safety of yellow fever vaccination for 102 HIV-infected patients

BACKGROUND: Yellow fever vaccine (17DV) has been investigated incompletely in human immunodeficiency virus (HIV)-infected patients, and adequate immunogenicity and safety are of concern in this population. METHODS: In the Swiss HIV Cohort Study, we identified 102 patients who received 17DV while they were HIV infected. We analyzed neutralization titers (NTs) after 17DV administration using the plaque reduction neutralization test. NTs of 1:>or=10 were defined as reactive, and those of 1:<10 were defined as nonreactive, which was considered to be nonprotective. The results were compared with data for HIV-uninfected individuals. Serious adverse events were defined as hospitalization or death within 6 weeks after receipt of 17DV. RESULTS: At the time of 17DV administration, the median CD4 cell count was 537 cells/mm(3) (range, 11-1730 cells/mm(3)), and the HIV RNA level was undetectable in 41 of 102 HIV-infected patients. During the first year after vaccination, fewer HIV-infected patients (65 [83%] of 78; P = .01) than HIV-uninfected patients revealed reactive NTs, and their NTs were significantly lower (P < .001) than in HIV-uninfected individuals. Eleven patients with initially reactive NTs lost these reactive NTs

A Photoperiod-Insensitive Barley Line Contains a Light-Labile Phytochrome B1

Barley (Hordeum vulgare L.) is a long-day plant whose flowering is enhanced when the photoperiod is supplemented with far-red light, and this promotion is mediated by phytochrome. A chemically mutagenized dwarf cultivar of barley was selected for early flowering time (barley maturity daylength response [BMDR]-1) and was made isogenic with the cultivar Shabet (BMDR-8) by backcrossing. BMDR-1 was found to contain higher levels of both phytochrome A and phytochrome B in the dark on immunoblots with monoclonal antibodies from oat (Avena sativa L.) that are specific to different members of the phytochrome gene family. Phytochrome A was light labile in both BMDR-1 and BMDR-8, decreasing to very low levels after 4 d of growth in the light. Phytochrome B was light stable in BMDR-8, being equal in both light and darkness. However, phytochrome B became light labile in BMDR-1 and this destabilization of phytochrome B appeared to make BMDR-1 insensitive to photoperiod. In addition, both the mutant and the wild type lacked any significant promotion of flowering in response to a pulse of far-red light given at the end of day, and the end-of-day, far-red inhibition of tillering is normal in both, suggesting that phytochrome B is not involved with these responses in barley.