Challenges in the research and development of new human vaccines

The field of vaccinology was born from the observations by the fathers of vaccination, Edward Jenner and Louis Pasteur, that a permanent, positive change in the way our bodies respond to life-threatening infectious diseases can be obtained by specific challenge with the inactivated infectious agent performed in a controlled manner, avoiding the development of clinical disease upon exposure to the virulent pathogen. Many of the vaccines still in use today were developed on an empirical basis, essentially following the paradigm established by Pasteur, "isolate, inactivate, and inject" the disease-causing microorganism, and are capable of eliciting uniform, long-term immune memory responses that constitute the key to their proven efficacy. However, vaccines for pathogens considered as priority targets of public health concern are still lacking. The literature tends to focus more often on vaccine research problems associated with specific pathogens, but it is increasingly clear that there are common bottlenecks in vaccine research, which need to be solved in order to advance the development of the field as a whole. As part of a group of articles, the objective of the present report is to pinpoint these bottlenecks, exploring the literature for common problems and solutions in vaccine research applied to different situations. Our goal is to stimulate brainstorming among specialists of different fields related to vaccine research and development. Here, we briefly summarize the topics we intend to deal with in this discussion.

Leishmanial infection: analysis of its first steps: a review

The first steps in leishmaniasis are critical in determining the evolution of the disease. Major advances have recently been done in understanding this crucial moment. Fundamental research in parasite-vector interaction, parasite biology, insect saliva, and vertebrate host response have shed new light and uncovered a most fascinating and complex moment in leishmaniasis. We review here some of these aspects and we try to connect them in a logical framework.

B-cell infiltration and frequency of cytokine producing cells differ between localized and disseminated human cutaneous leishmaniases

Biopsies from human localized cutaneous lesions (LCL n = 7) or disseminated lesions (DL n = 8) cases were characterized according to cellular infiltration,frequency of cytokine (IFN-g, TNF-alpha) or iNOS enzyme producing cells. LCL, the most usual form of the disease with usually one or two lesions, exhibits extensive tissue damage. DL is a rare form with widespread lesions throughout the body; exhibiting poor parasite containment but less tissue damage. We demonstrated that LCL lesions exhibit higher frequency of B lymphocytes and a higher intensity of IFN-gamma expression. In both forms of the disease CD8+ were found in higher frequency than CD4+ T cells. Frequency of TNF-alpha and iNOS producing cells, as well as the frequency of CD68+ macrophages, did not differ between LCL and DL. Our findings reinforce the link between an efficient control of parasite and tissue damage, implicating higher frequency of IFN-gamma producing cells, as well as its possible counteraction by infiltrated B cells and hence possible humoral immune response in situ

Interleukin 8 as a vaso-occlusive marker in Brazilian patients with sickle cell disease

Sickle cell disease has a worldwide distribution and is a public health problem in Brazil. Although vaso-occlusive crisis (VOC) is one of the most important clinical features of the disease, there are still several steps of its pathogenesis which are unknown. The increase of the chemotactic factor interleukin 8 (IL-8) has been reported to be involved in sickle cell disease crisis, but this has not been demonstrated conclusively. In the present study we analyzed serum IL-8 levels by ELISA and hematological parameters and hemoglobin patterns by standard techniques in 23 (21 SS and 2 SC) Brazilian patients with sickle cell syndromes during VOC caused by different inducing factors, 22 (21 SS and 1 SC) sickle cell patients out of crisis, and 11 healthy controls. Increased IL-8 levels were observed in 19 of 23 VOC patients (79.2 percent), 3 of them with more than 1,000 pg/ml. Seventeen of 22 (77.3 percent) non-crisis patients showed low IL-8 levels (less than 15 pg/ml). Healthy controls had low IL-8 levels. A significant difference in serum IL-8 levels was observed between crisis and non-crisis sickle cell patients (P<0.0001). There was no correlation between IL-8 levels and hematological data or hemoglobin patterns. High serum IL-8 levels were observed in VOC patients independently of the crisis-inducing factor. We conclude that in the studied population, IL-8 concentration may be a useful VOC marker, although the mechanism of the pathogenic process of sickle cell VOC syndromes remains unclear

A dhfr-ts- Leishmania major Knockout Mutant Cross-protects against Leishmania amazonensis

E10-5A3 is a dhfr-ts- Leishmania major double knockout auxotrophic shown previously to induce substantial protection against virulent L. major infection in both genetically susceptible and resistant mice. We investigated the capacity of dhfr-ts- to protect against heterologous infection by L. amazonensis. The degree of protection was evaluated by immunization of BALB/c or C57BL/6 mice with E10-5A3, followed by L. amazonensis challenge. Whether immunized by subcutaneous (SC) or intravenous (IV) inoculation, susceptible and resistant mice displayed a partial degree of protection against challenge with virulent L. amazonensis. SC-immunized BALB/c mice developed lesions 40 to 65 percent smaller than non immunized mice, while IV immunization led to protection ranging from 40 to 75 percent in four out of six experiments compared to non immunized animals. The resistant C57BL/6 mice displayed comparable degrees of protection, 57 percent by SC and 49 percent by IV immunization. Results are encouraging as it has been previously difficult to obtain protection by SC vaccination against Leishmania, the preferred route for human immunization

Valor da determinaçäo da atividade de adenosina desaminase (ADA) no diagnóstico diferencial dos derrames pleurais / Value of determining the activity of adenosine deaminase (ADA) in the differenrial diagnosis of pleural effusions

Justificativa. Derrame pleural é um problema freqüentemente encontrado na prática clínica. Enquanto o derrame pleural transudativo, geralmente, nao apresenta dificuldade no diagnóstico, as efusoes exsudativas necessitam de um diagnóstico diferencial cuidadoso que inclui, necessariamente, tuberculose e neoplasia metastática para a pleura. Métodos. Num estudo transversal, foram estudados 221 pacientes consecutivos, com derrame pleural persistente e/ou nao eslarecido, em um hospital de refência para doenças respiratórias na rede pública estadual, com o objetivo de avaliar a acurácia da determinaçao da atividade da adenosina desaminase (ADA) no líquido pleural para o diagnóstico de tuberculose. Esses pacientes foram enquadrados nos seguintes grupos: a) tuberculose (confirmada, n=150; provável, n=9); b) neoplasia (confirmada, n=21; provável, n=16; linfoma, n=3); e c) miscelânea (n=22). Os pacientes foram submetidos a exame clínico, radiografias de tórax, testes sanguíneos e toracocenteses com biópsias pleurais. No líquido pleural foram realizados os exames de rotina com adicional determinaçao da atividade da ADA pelo método de Giusti. Resultados. Estudando a inter-relaçao entre sensibilidade e especificidade da atividade da ADA em diferentes níveis de corte, foi determinado que o melhor nível seria o de 40U/L. assim, observou-se sensibilidade de 93,3 por cento, especificidade de 93,5 por cento, valor preditivo positivo de 97,2 por cento e valor preditivo negativo de 85,3 por cento, quando analisados apenas os pacientes com tuberculose confirmada e os nao-tuberculosos. Três dos quatro pacientes com elevada atividade da ADA, sem tuberculose, tinham linfoma. Conclusao. A determinaçao da atividade da ADA no líquido pleural é um exame de baixo custo, de técnica simples e rápida, tem alta sensibilidade e especificidade para identificar pacientes com pleurite tuberculosa. Os achados do presente estudo sao comparáveis a outras observaçoes publicadas, demonstrando a utilidade da incorporaçao deste teste na avaliaçao rotineira dos derrames pleurais em áreas com alta prevalência de tuberculose.

Transforming growth factor-ß in tegumentary leishmaniasis

1. The course of infection with the protozoan parasite Leishmania is determined in part by its early replication in macrophages, the exclusive host cells for these organisms. Resistance to and recovery from leishmanial infection is related to cell-mediated immune responses in all forms of human and murine leishmaniasis. 2. Factors contributing to the early inhibition or proliferation of Leishmania are poorly understood, but cytokines such as IFNÔ, IL-10 or transforming growth factor ß (TGF-ß) are known to influence the replication of Leishmania in macrophages. 3. TGF-ß is a multipotential cytokine with diverse effects on cells of the immune system, including down-regulation of certain macrophage functions. Infection of murine or human macrophages by Leishmania induces the production of active TGF-ß. Recombinant TGF-ß added to murine or human macrophage cultures leads to increased intracellular replication of Leishmania. Exogenous TGF-ß administered in vivo promotes enhancement of infection, whereas its neutralization by monoclonal antibodies decreases the level of in vitro infection, and protects susceptible mice. 4. Susceptible animals treated with anti-TGF-ß monoclonal antibodies change their immune response, not increasing the expression of IL-4 while increasing the expression of IFNÔ mRNA in their draining lymph nodes. Resistant animals treated with TGF-ß also change their pattern of immune response as indicated by an increase of the important Th2 cytokine IL-10 mRNA in the draining lymph node. 5. TGF-ß has profound effects on the host response to Leishmania in both mouse and man, and probably is an important parasite escape mechanism

Immunological studies with the venom of the scorpion Tityus serrulatus

We describe a "sandwich" enzyme-linkedimmunosorbent assay (ELISA) sensitive to quantities of scorpion (Tityus serrulatus) venom (TsV) in the range of 1-3 ng?ml sample. Cross-reactivity with the venom from the rattlesnake Crotalus durissus terrificus and with venoms from several snakes of the Bothrops genus was detected only at concentrations higher than 1 *g/ml sample. A conventional ELISA is also described for the detection of antibodies against TsV. Analysis by Western Blot (WB) demonstrated a 25-kDa protein band common to TsV and to the venoms of Bothrops moojeni, B. jararacussu and B. jararaca. Venom from C. d. terrificus exhibited WB cross-reactive bands of 16 and 25 kDa with TsV

Gamma interferon production by lymphocytes from children infected with L. chagasi

The present study was performed to evaluate the ability of lymphocytes from 18 children living in an endemic area of visceral leishmaniasis (VL) to produce gamma-interferon. These children had no previous history of VL and were considered to be infected with Leishmania chagasi based on leishamnial seroconversion. The gamma IFN levels were determined by radioimmunoassay on supernatants of lymphocyte cultures (3 x 10**6/ml). stimulate with PHA (final dilution 1:10) and Leishamnia chagasi antigen (10µg/ml). The gamma-IFN production by lymphocytes from seroconverting children stimulated with PHA (178 ñ 151 U/ml) and Leishmania chagasi (47 ñ 77 U/ml) was significantly higher than that observed in visceral leishmaniasis. For clinical follow-up, these 18 seroconverting children were divided into three groups: asymptomatic infection (N=4); self-healing subclinical illness (N=9), and sublinical infection progressing to VL (N=5). Gamma IFN levels inchildren with either asymptomatic or subclinical infection (65 ñ 85 U/ml were significantly higher (P < 0.003) than those observed in children progressing to VL (9 ñ 6 U/ml). The data demonstrate that there is an association between gamma IFN levels and the clinical course of Leishmania infection

Serum interferon activity of patients with leishmaniasis

Serum from a significant proportion of 29 cutaneous and 12 mucocutaneous leishmaniasis patients exhibited interferon activity in a cytopathic assay: positive tests were obtained for 24.1% and 41.7% of the patients, respectively. Similar positive frequencies were observed in other parasitic diseases (schistosomiasis, 12.5%; toxoplasmosis, 20%; Chagas' disease, 16%; leprosy, 12.5%; tuberculosis, 30%). In contrast, none of the 44 serum samples from American visceral leishmaniasis (AVL) patients had interferon activity during the active stage of the disease. However, 13% of the samples obtained from patients recovered from AVL were positive

Isolation and funectional characterization of a mitogenic lection from the marine sponge Cinachyrella alloclada

1. A D-galactose-specific lectin was isolated from crude extracts of the marine sponge Cinachyrella alloclada by affinity chromatography on sepharose 4B. 2. The lectin agglutinated human erythrocytes irrespective of ther ABO group antigens. 3. Hemagglutination inhibition tests indicated that the lectin binds D-galactose or carbohydrates having a terminal nonreducing D-galactosyl group. 4. C. alloclada lectin was mitogenic for human periheral blood lymphocytes when AB serum was omitted during the first 24 h of culture. 5 Human serum apparently contains substances which bind or inactivate this lectin