RESUMO
The HIV epidemic in Argentina is characterized by the high prevalence of infections caused by subtype B and BF variants. In this study, the Nef protein was used as a tool to study the impact of HIV-1 BF variants in the design of future vaccines. DNA and MVA vectors expressing Nef of the CRF12_BF recombinant form of HIV-1 were generated and characterized. After the administration of single DNAprime/MVAboost immunization schedules in Balb/c mice we found that NefBF delivered from these vectors generated a response of high specificity with low cross-reactivity against subtype B. But, when a more potent response was induced after 3 priming DNA doses and a booster with MVA virus, cross-reactivity against NefB was detected, although of lower magnitude than the NefBF specific. These results will be pivotal for vaccines designs in our region, indicating that antigens from these viral variants must be considered for a future vaccine.
Assuntos
Vacinas contra a AIDS/imunologia , HIV-1/imunologia , Vacinas de DNA/imunologia , Vaccinia virus/genética , Produtos do Gene nef do Vírus da Imunodeficiência Humana/imunologia , Vacinas contra a AIDS/genética , Animais , Anticorpos Neutralizantes/sangue , Linhagem Celular , Chlorocebus aethiops , Cricetinae , Reações Cruzadas , Vetores Genéticos , Anticorpos Anti-HIV/sangue , Infecções por HIV/prevenção & controle , HIV-1/genética , Imunização Secundária/métodos , Interferon gama/metabolismo , Leucócitos Mononucleares/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Vacinas de DNA/genética , Vacinas de Subunidades Antigênicas/genética , Vacinas de Subunidades Antigênicas/imunologia , Produtos do Gene nef do Vírus da Imunodeficiência Humana/genéticaRESUMO
The well-established model of Chagas' disease in "l" rats was used to evaluate the effects of three injections of heat-killed Gordonia bronchialis, Rhodococcus coprophilus or saline on Trypanosoma cruzi parasitaemia and acute and chronic myocarditis, sequelae of the infection. Two vaccinating injections were given prior to challenge with T. cruzi, and the third, immunotherapeutic, injection was given 7 days after challenge. Treatment with either actinomycete significantly reduced acute parasitaemia (p<0.04), modified cellular infiltration during acute myocarditis and limited chronic myocarditis (p<0.03) in comparison with the saline-treated control animals. Immunological investigations showed that both bacterial preparations achieved their results through different mechanisms. The relevance of our findings to human Chagas' disease is discussed.
Assuntos
Actinomycetales/imunologia , Doença de Chagas/imunologia , Imunização , Animais , Anticorpos Antiprotozoários/sangue , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Cardiomiopatia Chagásica/imunologia , Microbiologia Ambiental , Imunoglobulina G/sangue , Masculino , Parasitemia/prevenção & controle , Ratos , SuspensõesRESUMO
Earlier work in Trypanosoma cruzi-infected C57BL/6 and BALB/c mice revealed an acute disease, of lethal outcome in the former group and lesser severity in BALB/c mice. Fatal course was not accompanied by an increased parasite load, but by a substantial imbalance between pro- and anti-inflammatory cytokine serum levels. To better characterise the mechanisms allowing the host to restrain the infection, we have now studied the specific IgG production and in vitro behaviour of peritoneal macrophages (PMs) when exposed to T. cruzi. BALC/c mice displayed higher serum levels of specific immunoglobulins in the first weeks of acute infection. In vitro infected PMs showed no between-group differences in the number of intracellular parasites, although TNFalpha levels were significantly higher in culture supernatants from C57BL/6 mice. Because an LPS-based pretreatment (desensitisation protocol followed by a sublethal LPS dose) reduced disease severity of C57BL/6 mice, we next explored the features of the in vitro infection in PMs from mice subjected to such protocol. PMs from LPS-pretreated mice had a decreased production of TNFalpha and IL-1beta, becoming more permissive to parasite replication. It is concluded that deficient control of T. cruzi infection in C57BL/6 mice may also involve a less satisfactory specific IgG response and increased TNFalpha production by PMs. Improved disease outcome in LPS-pretreated mice may be associated with the reduced inflammatory cytokine production by PMs, but the impaired ability of these cells to control parasite growth suggests that compensatory mechanisms are operating in the in vivo situation.
Assuntos
Doença de Chagas/imunologia , Citocinas/metabolismo , Imunoglobulina G/imunologia , Macrófagos Peritoneais/metabolismo , Trypanosoma cruzi/imunologia , Animais , Citocinas/imunologia , Primers do DNA , Ensaio de Imunoadsorção Enzimática , Técnica Indireta de Fluorescência para Anticorpo , Interleucina-1/imunologia , Interleucina-1/metabolismo , Lipopolissacarídeos , Macrófagos Peritoneais/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Estatísticas não Paramétricas , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/imunologia , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Inoculation at weaning with Trypanosoma cruzi in inbred "l" rats resulted in a self-resolving acute infection characterized by marked parasitaemias, whereas challenge to adult rats revealed a mild disease with extremely low parasitaemias. To explore the mechanisms underlying such age-associated differences in disease outcome, we analysed the in vitro replication of T. cruzi, nitric oxide and tumour necrosis factor-alpha (TNF-alpha) production in peritoneal macrophages (PMs), the serum concentrations of the specific immunoglobulins (Igs) IgM and IgG, antibodies exhibiting lytic activity against bloodstream forms of T. cruzi and circulating levels of nitrate, TNF-alpha and interferon-gamma (IFN-gamma). Macrophages from young rats were as effective as their adult counterparts for restraining intracellular parasite replication. When stimulated with IFN-gamma, culture supernatants from young PMs contained higher amounts of nitrite and TNF-alpha. Serum samples from 4 and 7 days post infection revealed easily detectable amounts of nitrate, with values being further augmented by day 7 post infection and significantly higher in the young group. TNF-alpha levels were only detected in the young group by day 7 post infection. Both groups had increased amounts of IFN-gamma in their sera, although in adult rats, this trend was followed by a significant drop at day 7, with young rats showing values still higher by the same time point evaluation. In contrast, young rats presented significantly lower levels of IgM and IgG antibodies during the first week of infection. Increased resistance in adult rats seems to be the result of a more appropriate antibody production.