Production of glycosylphosphatidylinositol-anchored proteins for vaccines and directed binding of immunoliposomes to specific cell types

Liposomes are highly useful carriers for delivering drugs or antigens. The association of glycosylphosphatidylinositol (GPI)-anchored proteins to liposomes potentially enhances the immunogenic effect of vaccine antigens by increasing their surface concentration. Furthermore, the introduction of a universal immunoglobulin-binding domain can make liposomes targetable to virtually any desired receptor for which antibodies exist. Methods: We developed a system for the production of recombinant proteins with GPI anchors and histidine tags and Strep-tags for simplified purification from cells. This system was applied to i) the green fluorescent protein (GFP) as a reporter, ii) the promising Plasmodium falciparum vaccine antigen PfRH5 and iii) a doubled immunoglobulin Fc-binding domain termed ZZ from protein A of Staphylococcus aureus. As the GPI-attachment domain, the C-terminus of murine CD14 was used. After the recovery of these three recombinant proteins from Chinese hamster ovary (CHO) cells and association with liposomes, their vaccine potential and ability to target the CD4 receptor on lymphocytes in ex vivo conditions were tested. Results: Upon immunization in mice, the PfRH5-GPI-loaded liposomes generated antibody titers of 103 to 104, and showed a 45% inhibitory effect on in vitro growth at an IgG concentration of 600 µg/mL in P. falciparum cultures. Using GPI-anchored ZZ to couple anti-CD4 antibodies to liposomes, we created immunoliposomes with a binding efficiency of 75% to CD4+ cells in splenocytes and minimal off-target binding. Conclusions: Proteins are very effectively associated with liposomes via a GPI-anchor to form proteoliposome particles and these are useful for a variety of applications including vaccines and antibody-mediated targeting of liposomes. Importantly, the CHO-cell and GPI-tagged produced PfRH5 elicited invasion-blocking antibodies qualitatively comparable to other approaches.(AU)

Recent Patents Applications in Red Biotechnology: A Mini-Review.

BACKGROUND: The different fields of biotechnology can be classified by colors, as a "rainbow" methodology. In this sense, the red biotechnology, focused on the preservation of health, has been outstanding in helping to solve this challenge through the provision of technologies, including diagnostic kits, molecular diagnostics, vaccines, innovations in cancer research, therapeutic antibodies and stem cells. OBJECTIVE: The main goal of this work is to highlight the different areas within the red Biotechnology. In this sense, we revised some patents regarding red biotechnology as examples to cover this subject. METHODS: A literature search of patents was performed from the followings Patents Database: INPI, USPTO, Esp@cenet, WIPO and Google Patents. RESULTS: Our analysis showed the following numbers from patents found: cancer research (8), diagnosis kit (9), vaccines (8), stem cells (9) and therapeutic antibodies (5), where the United States is the leader for most filled patents in Red Biotechnology. CONCLUSION: This mini-review has provided an update of some patents on Recent Patents in Red Biotechnology. As far as we know, this is the first mini-review report on Red Biotechnology based on patents.

Optimization of the Production of Inactivated Clostridium novyi Type B Vaccine Using Computational Intelligence Techniques.

Clostridium novyi causes necrotic hepatitis in sheep and cattle, as well as gas gangrene. The microorganism is strictly anaerobic, fastidious, and difficult to cultivate in industrial scale. C. novyi type B produces alpha and beta toxins, with the alpha toxin being linked to the presence of specific bacteriophages. The main strategy to combat diseases caused by C. novyi is vaccination, employing vaccines produced with toxoids or with toxoids and bacterins. In order to identify culture medium components and concentrations that maximized cell density and alpha toxin production, a neuro-fuzzy algorithm was applied to predict the yields of the fermentation process for production of C. novyi type B, within a global search procedure using the simulated annealing technique. Maximizing cell density and toxin production is a multi-objective optimization problem and could be treated by a Pareto approach. Nevertheless, the approach chosen here was a step-by-step one. The optimum values obtained with this approach were validated in laboratory scale, and the results were used to reload the data matrix for re-parameterization of the neuro-fuzzy model, which was implemented for a final optimization step with regards to the alpha toxin productivity. With this methodology, a threefold increase of alpha toxin could be achieved.

Refolding of the recombinant protein Sm29, a step toward the production of the vaccine candidate against schistosomiasis.

Schistosomiasis is an important parasitic disease, with about 240 million people infected worldwide. Humans and animals can be infected, imposing an enormous social and economic burden. The only drug available for chemotherapy, praziquantel, does not control reinfections, and an efficient vaccine for prophylaxis is still missing. However, the tegumental protein Sm29 of Schistosoma mansoni was shown to be a promising antigen to compose an anti-schistosomiasis vaccine. Though, recombinant Sm29 is expressed in Escherichia coli as insoluble inclusion bodies requiring an efficient process of refolding, thus, hampering its production in large scale. We present in this work studies to refold the recombinant Sm29 using high hydrostatic pressure, a mild condition to dissociate aggregated proteins, leading to refolding on a soluble conformation. Our studies resulted in high yield of rSm29 (73%) as a stably soluble and structured protein. The refolded antigen presented protective effect against S. mansoni development in immunized mice. We concluded that the refolding process by application of high hydrostatic pressure succeeded, and the procedure can be scaled-up, allowing industrial production of Sm29.

Developing country applications of molecular farming: case studies in South Africa and Argentina.

Molecular farming is a technology that is very well suited to being applied in developing countries, given the reasonably high level of expertise in recombinant plant development in many centers. In addition, there is an urgent need for products such as inexpensive vaccines and therapeutics for livestock and for some human diseases - and especially those that do not occur or are rare in developed regions. South Africa and Argentina have been at the fore in this area among developing nations, as researchers have been able to use plants to produce experimental therapeutics such as nanoantibodies against rotavirus and vaccines against a wide variety of diseases, including Rabbit haemorrhagic disease virus, Foot and mouth disease virus, Bovine viral diarrhoea virus, bovine rotaviruses, Newcastle disease virus, rabbit and human papillomaviruses, Bluetongue virus, and Beak and feather disease virus of psittacines. A combination of fortuitous scientific expertise in both places, coupled with association with veterinary and human disease research centers, has enabled the growth of research groups that have managed to compete successfully with others in Europe and the USA and elsewhere, to advance this field. This review will cover relevant work from both South Africa and Argentina, as well as a discussion about the perspectives in this field for developing nations.

Brazilian avian metapneumovirus subtypes A and B: experimental infection of broilers and evaluation of vaccine efficacy / Metapneumovirus aviário subtipos A e B brasileiros: infecção experimental em frangos de corte e eficácia vacinal

Avian metapneumovirus (aMPV) is a respiratory pathogen associated with the swollen head syndrome (SHS) in chickens. In Brazil, live aMPV vaccines are currently used, but subtypes A and, mainly subtype B (aMPV/A and aMPV/B) are still circulating. This study was conducted to characterize two Brazilian aMPV isolates (A and B subtypes) of chicken origin. A challenge trial to explore the replication ability of the Brazilian subtypes A and B in chickens was performed. Subsequently, virological protection provided from an aMPV/B vaccine against the same isolates was analyzed. Upon challenge experiment, it was shown by virus isolation and real time PCR that aMPV/B could be detected longer and in higher amounts than aMPV/A. For the protection study, 18 one-day-old chicks were vaccinated and challenged at 21 days of age. Using virus isolation and real time PCR, no aMPV/A was detected in the vaccinated chickens, whereas one vaccinated chicken challenged with the aMPV/B isolate was positive. The results showed that aMPV/B vaccine provided a complete heterologous virological protection, although homologous protection was not complete in one chicken. Although only one aMPV/B positive chicken was detected after homologous vaccination, replication in vaccinated animals might allow the emergence of escape mutants.

O Metapneumovírus aviário (aMPV) é um patógeno respiratório associado à síndrome da cabeça inchada (SHS) em galinhas. Apesar de vacinas vivas contra o aMPV serem utilizadas no Brasil, os subtipos A e B (aMPV/A e aMPV/B) são ainda encontrados no país, com predominância do subtipo B. Este estudo foi conduzido com o intuito de estudar dois isolados brasileiros de aMPV (subtipos A e B) isolados de frango. Para isto, um desafio experimental em frangos foi conduzido com o intuito de explorar a capacidade de replicação dos subtipos A e B Brasileiros. Posteriormente, a protecção virológica conferida por uma vacina do subtipo B em pintos foi realizada com os mesmos isolados. Após o desafio experimental demonstrou-se, por isolamento viral e PCR em tempo real, que o isolado do subtipo B replicou por maior período de tempo e em quantidades maiores, em comparação com o subtipo A. Para o estudo de proteção, 18 pintos de um dia de idade foram vacinados e desafiados aos 21 dias. Usando isolamento viral e PCR em tempo real, em nenhuma ave vacinada e desafiada com aMPV/A foi detectado o vírus, ao passo que uma ave vacinada e desafiada com o aMPV/B foi positiva. Os resultados mostraram que a vacina do subtipo B forneceu protecção heteróloga completa, embora a protecção homóloga não tenha sido conferida em uma ave. Apesar de o aMPV/B ter sido detectado em apenas um frango após vacinação homóloga, a replicação viral em aves vacinadas pode resultar em emergência de mutantes de escape.

Brazilian avian metapneumovirus subtypes A and B: experimental infection of broilers and evaluation of vaccine efficacy / Metapneumovirus aviário subtipos A e B brasileiros: infecção experimental em frangos de corte e eficácia vacinal

Avian metapneumovirus (aMPV) is a respiratory pathogen associated with the swollen head syndrome (SHS) in chickens. In Brazil, live aMPV vaccines are currently used, but subtypes A and, mainly subtype B (aMPV/A and aMPV/B) are still circulating. This study was conducted to characterize two Brazilian aMPV isolates (A and B subtypes) of chicken origin. A challenge trial to explore the replication ability of the Brazilian subtypes A and B in chickens was performed. Subsequently, virological protection provided from an aMPV/B vaccine against the same isolates was analyzed. Upon challenge experiment, it was shown by virus isolation and real time PCR that aMPV/B could be detected longer and in higher amounts than aMPV/A. For the protection study, 18 one-day-old chicks were vaccinated and challenged at 21 days of age. Using virus isolation and real time PCR, no aMPV/A was detected in the vaccinated chickens, whereas one vaccinated chicken challenged with the aMPV/B isolate was positive. The results showed that aMPV/B vaccine provided a complete heterologous virological protection, although homologous protection was not complete in one chicken. Although only one aMPV/B positive chicken was detected after homologous vaccination, replication in vaccinated animals might allow the emergence of escape mutants.(AU)

O Metapneumovírus aviário (aMPV) é um patógeno respiratório associado à síndrome da cabeça inchada (SHS) em galinhas. Apesar de vacinas vivas contra o aMPV serem utilizadas no Brasil, os subtipos A e B (aMPV/A e aMPV/B) são ainda encontrados no país, com predominância do subtipo B. Este estudo foi conduzido com o intuito de estudar dois isolados brasileiros de aMPV (subtipos A e B) isolados de frango. Para isto, um desafio experimental em frangos foi conduzido com o intuito de explorar a capacidade de replicação dos subtipos A e B Brasileiros. Posteriormente, a protecção virológica conferida por uma vacina do subtipo B em pintos foi realizada com os mesmos isolados. Após o desafio experimental demonstrou-se, por isolamento viral e PCR em tempo real, que o isolado do subtipo B replicou por maior período de tempo e em quantidades maiores, em comparação com o subtipo A. Para o estudo de proteção, 18 pintos de um dia de idade foram vacinados e desafiados aos 21 dias. Usando isolamento viral e PCR em tempo real, em nenhuma ave vacinada e desafiada com aMPV/A foi detectado o vírus, ao passo que uma ave vacinada e desafiada com o aMPV/B foi positiva. Os resultados mostraram que a vacina do subtipo B forneceu protecção heteróloga completa, embora a protecção homóloga não tenha sido conferida em uma ave. Apesar de o aMPV/B ter sido detectado em apenas um frango após vacinação homóloga, a replicação viral em aves vacinadas pode resultar em emergência de mutantes de escape.(AU)

Vacina experimental produzida em cultivo celular confere proteção parcial contra o ectima contagioso em ovinos / Experimental vaccine produced in tissue culture confers partial protection against contagious ecthyma in sheep

O ectima contagioso (também conhecido como orf), é uma doença debilitante de ovinos e caprinos causada pelo vírus do orf (ORFV). A vacinação tem sido usada com relativo sucesso no controle da doença. No entanto, as vacinas atuais contêm amostras virulentas do agente, são produzidas por escarificação cutânea de animais, e apresentam eficácia questionável. Assim, o presente trabalho teve como objetivo produzir e testar a eficácia de uma vacina experimental produzida em cultivo celular. A cepa IA-82 do ORFV foi submetida a 21 passagens em cultivo de células BHK-21 e usada para vacinar ovinos jovens (n=30), por escarificação cutânea na face interna da coxa. A vacinação produziu pústulas e crostas em 16 dos 30 ovinos vacinados, indicando imunização adequada. Noventa dias após a vacinação, ovinos vacinados (n=16) e controles (n=16) foram inoculados com uma cepa virulenta do ORFV (10(6,9)DICC50/mL) após escarificação na comissura labial. Todos os animais desenvolveram lesões típicas de ectima, incluindo hiperemia, vesículas, pústulas e crostas. No entanto, os animais vacinados desenvolveram lesões mais leves e passageiras do que os controles, e os escores clínicos foram estatisticamente diferentes (p<0,05) entre os dias 10 e 22 pós-desafio. Além disso, o tempo de duração da doença foi significativamente inferior (p<0,05) nos animais vacinados. Os animais vacinados também excretaram menor quantidade de vírus (p<0,05) e por um período significativamente mais curto do que os controles (13 dias versus 22 dias, p<0,001). Esses resultados demonstram a proteção parcial conferida pela vacina experimental e, dependendo da melhoria dos índices de imunização e proteção, são promissores no sentido da utilização de vacinas contra o ORFV produzidas em cultivo celular.

Contagious ecthyma, also known as orf, is a debilitating disease of sheep and goats caused by the parapoxvirus, orf virus (ORFV). Vaccination has been used with relative success to reduce the losses caused by the disease, yet the current vaccines contain virulent virus, are empirically produced through skin scarification of live lambs, and present questionable efficacy. Therefore, the present study aimed at developing and testing an experimental ORFV vaccine produced in tissue culture. The ORFV strain IA-82 was submitted to 21 passages in BHK-21 cells and then used to immunize lam bs (n=30) through skin scarification of the internal face of the hind limb. Vaccination produced localized pustules and scabs lesions in 16 out of 30 animals, indicating an adequate replication of the vaccine virus. Ninety days after vaccination, vaccinated (n=16) and control lambs (n=16) were inoculated with a virulent ORFV strain (10(6,9)TCID50/ml) in the labial commissure. Vaccinated and control lambs developed typical orf lesions, characterized by hyperemia, vesicles, pustules and scab formation. Nonetheless, vaccinated animals developed milder lesions compared to controls and the clinical scores were significantly lower (p<0.05) between days 10 and 22 post-challenge. In addition, the mean duration of clinical disease was significantly reduced in vaccinated animals (p<0.05). Furthermore, vaccinated animals excreted much less virus (p<0.05) and for a significantly shorter period of time than did the controls (13 days versus 22 days, p<0.001). These results demonstrate partial protection by the experimental vaccine and, upon improvement of immunization and protection indices, are promising towards the use of tissue culture-based ORFV vaccines.

Vacina experimental produzida em cultivo celular confere proteção parcial contra o ectima contagioso em ovinos / Experimental vaccine produced in tissue culture confers partial protection against contagious ecthyma in sheep

O ectima contagioso (também conhecido como orf), é uma doença debilitante de ovinos e caprinos causada pelo vírus do orf (ORFV). A vacinação tem sido usada com relativo sucesso no controle da doença. No entanto, as vacinas atuais contêm amostras virulentas do agente, são produzidas por escarificação cutânea de animais, e apresentam eficácia questionável. Assim, o presente trabalho teve como objetivo produzir e testar a eficácia de uma vacina experimental produzida em cultivo celular. A cepa IA-82 do ORFV foi submetida a 21 passagens em cultivo de células BHK-21 e usada para vacinar ovinos jovens (n=30), por escarificação cutânea na face interna da coxa. A vacinação produziu pústulas e crostas em 16 dos 30 ovinos vacinados, indicando imunização adequada. Noventa dias após a vacinação, ovinos vacinados (n=16) e controles (n=16) foram inoculados com uma cepa virulenta do ORFV (10(6,9)DICC50/mL) após escarificação na comissura labial. Todos os animais desenvolveram lesões típicas de ectima, incluindo hiperemia, vesículas, pústulas e crostas. No entanto, os animais vacinados desenvolveram lesões mais leves e passageiras do que os controles, e os escores clínicos foram estatisticamente diferentes (p<0,05) entre os dias 10 e 22 pós-desafio. Além disso, o tempo de duração da doença foi significativamente inferior (p<0,05) nos animais vacinados. Os animais vacinados também excretaram menor quantidade de vírus (p<0,05) e por um período significativamente mais curto do que os controles (13 dias versus 22 dias, p<0,001). Esses resultados demonstram a proteção parcial conferida pela vacina experimental e, dependendo da melhoria dos índices de imunização e proteção, são promissores no sentido da utilização de vacinas contra o ORFV produzidas em cultivo celular.(AU)

Contagious ecthyma, also known as orf, is a debilitating disease of sheep and goats caused by the parapoxvirus, orf virus (ORFV). Vaccination has been used with relative success to reduce the losses caused by the disease, yet the current vaccines contain virulent virus, are empirically produced through skin scarification of live lambs, and present questionable efficacy. Therefore, the present study aimed at developing and testing an experimental ORFV vaccine produced in tissue culture. The ORFV strain IA-82 was submitted to 21 passages in BHK-21 cells and then used to immunize lam bs (n=30) through skin scarification of the internal face of the hind limb. Vaccination produced localized pustules and scabs lesions in 16 out of 30 animals, indicating an adequate replication of the vaccine virus. Ninety days after vaccination, vaccinated (n=16) and control lambs (n=16) were inoculated with a virulent ORFV strain (10(6,9)TCID50/ml) in the labial commissure. Vaccinated and control lambs developed typical orf lesions, characterized by hyperemia, vesicles, pustules and scab formation. Nonetheless, vaccinated animals developed milder lesions compared to controls and the clinical scores were significantly lower (p<0.05) between days 10 and 22 post-challenge. In addition, the mean duration of clinical disease was significantly reduced in vaccinated animals (p<0.05). Furthermore, vaccinated animals excreted much less virus (p<0.05) and for a significantly shorter period of time than did the controls (13 days versus 22 days, p<0.001). These results demonstrate partial protection by the experimental vaccine and, upon improvement of immunization and protection indices, are promising towards the use of tissue culture-based ORFV vaccines.(AU)

Rhipicephalus (Boophilus) microplus: expression and characterization of Bm86-CG in Pichia pastoris.

The cattle tick Rhipicephalus (Boophilus) microplus is responsible for great economic losses. It is mainly controlled chemically, with limitations regarding development of resistance to the chemicals. Vaccines may help control this parasite, thereby reducing tick pesticide use. In this light, we performed subcloning of the gene of the protein Bm86-GC, the homologue protein that currently forms the basis of vaccines (Gavac(TM) and TickGard(PLUS)) that have been developed against cattle ticks. The subcloning was done in the pPIC9 expression vector, for transformation in the yeast Pichia pastoris. This protein was characterized by expression of the recombinant Mut+ strain, which expressed greater quantities of protein. The expressed protein (rBm86-CG) was recognized in the Western-blot assay using anti-Gavac, anti-TickGard, anti-larval extract and anti-rBm86-CG polyclonal sera. The serum produced in cattle vaccinated with the antigen CG rBm86 presented high antibody titers and recognized the native protein. The rBm86-GC has potential relevance as an immunogen for vaccine formulation against cattle ticks.

Rhipicephalus (Boophilus) microplus: expression and characterization of Bm86-CG in Pichia pastoris / Rhipicephalus (Boophilus) microplus: expressão e caracterização da Bm86-CG em Pichia pastoris

The cattle tick Rhipicephalus (Boophilus) microplus is responsible for great economic losses. It is mainly controlled chemically, with limitations regarding development of resistance to the chemicals. Vaccines may help control this parasite, thereby reducing tick pesticide use. In this light, we performed subcloning of the gene of the protein Bm86-GC, the homologue protein that currently forms the basis of vaccines (GavacTM and TickGardPLUS) that have been developed against cattle ticks. The subcloning was done in the pPIC9 expression vector, for transformation in the yeast Pichia pastoris. This protein was characterized by expression of the recombinant Mut+ strain, which expressed greater quantities of protein. The expressed protein (rBm86-CG) was recognized in the Western-blot assay using anti-Gavac, anti-TickGard, anti-larval extract and anti-rBm86-CG polyclonal sera. The serum produced in cattle vaccinated with the antigen CG rBm86 presented high antibody titers and recognized the native protein. The rBm86-GC has potential relevance as an immunogen for vaccine formulation against cattle ticks.

O carrapato-do-boi Rhipicephalus (Boophilus) microplus é responsável por grandes perdas econômicas. Seu controle é principalmente químico e apresenta limitações quanto ao desenvolvimento de resistência aos princípios ativos. As vacinas podem auxiliar no controle deste parasita diminuindo as aplicações de carrapaticidas. Considerando isso, foi realizada a subclonagem do gene da proteína Bm86-CG, proteína homologa a que atualmente é a base das vacinas desenvolvidas (GavacTM e TickGardPLUS) contra o carrapato-do-boi, no vetor de expressão pPIC9, para ser transformado em levedura, Pichia pastoris. Esta proteína foi caracterizada pela expressão da cepa recombinante Mut+ que expressou maior quantidade de proteína. A proteína expressa, rBm86-CG, foi reconhecida no ensaio de Western-blot pelos soros policlonais anti-Gavac, anti-TickGard, anti-Extrato de larva e anti-rBm86-CG. O soro produzido em bovinos vacinados com o antígeno rBm86-CG apresentou altos títulos de anticorpo e reconheceu a proteína nativa. A rBm86-CG possui potencial relevância como imunógeno para formulação vacinal contra o carrapato de bovinos.

Two decades of plant-based candidate vaccines: a review of the chimeric protein approaches.

Genetic engineering revolutionized the concept of traditional vaccines since subunit vaccines became reality. Additionally, over the past two decades plant-derived antigens have been studied as potential vaccines with several advantages, including low cost and convenient administration. More specifically, genetic fusions allowed the expression of fusion proteins carrying two or more components with the aim to elicit immune responses against different targets, including antigens from distinct pathogens or strains. This review aims to provide an update in the field of the production of plant-based vaccine, focusing on those approaches based on the production of chimeric proteins comprising antigens from human pathogens, emphasizing the case of cholera toxin/E. coli enterotoxin fusions, chimeric viruses like particles approaches as well as the possible use of adjuvant-producing plants as expression hosts. Challenges for the near future in this field are also discussed.

Robust artificial intelligence tool for automatic start-up of the supplementary medium feeding in recombinant E. coli cultivations.

One of the most important events in fed-batch fermentations is the definition of the moment to start the feeding. This paper presents a methodology for a rational selection of the architecture of an artificial intelligence (AI) system, based on a neural network committee (NNC), which identifies the end of the batch phase. The AI system was successfully used during high cell density cultivations of recombinant Escherichia coli. The AI algorithm was validated for different systems, expressing three antigens to be used in human and animal vaccines: fragments of surface proteins of Streptococcus pneumoniae (PspA), clades 1 and 3, and of Erysipelothrix rhusiopathiae (SpaA). Standard feed-forward neural networks (NNs), with a single hidden layer, were the basis for the NNC. The NN architecture with best performance had the following inputs: stirrer speed, inlet air, and oxygen flow rates, carbon dioxide evolution rate, and CO2 molar fraction in the exhaust gas.

Allelic diversity at the Merozoite surface protein-1 (MSP-1) locus in natural Plasmodium falciparum populations: a brief overview

The merozoite surface protein-1 (MSP-1) locus of Plasmodium falciparum codes for a major asexual blood-stage antigen currently proposed as a major malaria vaccine candidate. The protein, however, shows extensive polymorphism, which may compromise its use in sub-unit vaccines. Here we compare the patterns of allelic diversity at the MSP-1 locus in wild isolates from three epidemiologically distinct malaria-endemic areas: the hypoendemic southwestern Brazilian Amazon (n=54), the mesoendemic southern Vietnam (n=238) and the holoendemic northern Tanzania (n=79). Fragments of the variable blocks 2, 4a, 4b and 6 or 10 of this single-copy gene were amplified by the polymerase chain reaction, and 24 MSP-1 gene types were defined as unique combinations of allelic types in each variable block. Ten different MSP-1 types were identified in Brazil, 23 in Vietnam and 13 in Tanzania. The proportion of genetically mixed infections (isolates with carrying more one MSP-1 version) ranged from 39 per cent in Brazil to 44 per cent in Vietnam and 60 per cent in Tanzania. The vast majority (90 per cent) of the typed parasite populations from Brazil and Tanzania belonged to the same seven most frequent MSP-1 gene types. In contrast, these seven types corresponded to only 61 per cent of the typed parasite populations from Vietnam. Non-random associations were found between allelic types in blocks 4a and 6 among Vietnamese isolates, the same pattern being observed in independent studies performed in 1994, 1995 and 1996. These results suggest that MSP-1 is under selective pressure in the local parasite population. Nevertheless, the finding that similar MSP-1 type frequencies were found in 1994 and 1996 argues against the prominence of short-term frequency-dependent immune selection of MSP-1 polymorphisms. Non-random associations between MSP-1 allelic types, however, were not detected among isolates from Brazil and Tanzania. A preliminary analysis of the distribution od MSP-1 gene types per host among isolates from Tanzania, but not among those from Brazil and Vietnam, shows significant deviation from that expected under the null hypothesis of independent distribution of parasites carrying different gene types in the human hosts. Some epidemiological consequences of these findings are discussed.

An overview of health-related industrial biotechnology in Latin America and the Caribbean.

There is some uncertainty about the extent to which Latin America and the Caribbean have participated in the advances of health-related industrial biotechnology. This article reviews the available literature and seeks to provide an overview of the prevailing situation. In general, national governments and multinational agencies have provided most of the health-related biotechnology investments within this region. Efforts to achieve technology transfers, a subject of prime concern, have been developed by a number of programs including the WHO Special Program for Research and Training in Tropical Diseases, the UNDP/UNESCO/UNIDO Regional Biotechnology Program for Latin America and the Caribbean; PAHO's Program for the Regional Development of Biotechnology as Applied to Health; The PAHO/WHO Expanded Program on Immunization (EPI); and PAHO's Regional System of Vaccines (SIREVA). Regarding current production capacity, some successful efforts have been made to produce a variety of therapeutic products including recombinant and natural interferons, interleukins, insulin, and recombinant streptokinase; but in general the region's current potential in this area is at best incipient and uncertain. However, the region does have a limited ability to make diagnostic products and a well-established capacity for vaccine development. Overall, this picture suggests that the region has the potential to play a small but significant role in health-related biotechnology.

An overview of health-related industrial biotechnology in Latin American and the Caribbean

There is some uncertainty about the extent to which Latin America and the Caribbean have participated in the advances of health-related industrial biotechnology. This article reviews the available literature and seeks to provide an overview of the prevailing situation. In general, national governments and multinational agencies have provided most of the health-related biotechnology investments within this region. Efforts to achieve technology transfers, a subject of prime concern, have been developed by a number of programs including the WHO Special Programme for Research and Training in Tropical Diseases, the UNDP/UNESCO/UNIDO Regional Biotechnology Program for Latin America and the Caribbean; PAHO's Program for the Regional Development of Biotechnology as Applied to Health; the PAHO/WHO Expanded Program of Immunization (EPI); and PAHO's Regional System of Vaccines (SIREVA). Regarding current production capacity, some successful efforts have been made to produce a variety of therapeutic products including recombinant and natural ionterferons, interleukins, insulin, and recombinant streptokinase; but in general the region's current potential in this area is at best incipient and uncertain. However, the region does have a limited ability to make diagnostic products and a well-established capacity for vaccine development. Overall, this picture suggests that the region has the potential to play a small but significant role in health-related biotechnology (AU).

Vacunación contra la shigelosis / Vaccination against shigelosis

Se define como shigelosis a la enfermedad intestinal producida por las diferentes especies del género Shigella, de las cuales el humano es el principal hospedero. Shigella es un bacilo corto, Gram-negativo, de la familia Enterobacteriaceae. La shigelosis se manifiesta en tres formas: 1) disentería clásica (sangre, moco, pus), 2) diarrea acuosa no complicada y 3) una combinación de disentería y diarrea acuosa. La mayoría de los casos de diarrea acuosa no son distinguibles de las que son ocacionadas por otras etiologías. Concluye el documento enfatizando que, no existe hasta el momento actual ninguna vacuna contra Shigella que pueda ser recomendable para la aplicación en población general. Todos los esfuerzos hasta ahora realizados han quedado en pequeños estudios en voluntarios, en los cuales se han obtenido fracasos y en otros ensayos se han vislumbrado posibles vacunas para emplear en el futuro. Dentro de los modelos experimentales de vacunas que hasta el momento hay, se está intentando corregir los posibles errores y por otra parte conjuntar los mecanismos de acción propuestos para cada tipo de vacuna. Finalmente si la shigelosis es un problema de salud pública, principalmente en los países en vías de desarrollo, son importantes los esfuerzos para lograr obtener una vacuna que en lo futuro pueda reducir uno de los principales problemas de morbilidad infantil

Nuevos enfoques en la obtención de vacunas / New approaches in the attainment of vaccines

Las llamadas vacunas de nueva generación incluyen a aquellas que no se preparan con un enfoque tradicionalista, es decir no usan al patógeno completo: virus, bacteria, protozoario, etc. atenuado o muerto. Su desarrollo conjunta información inmunológica y los avances en las técnicas de biología molecular. Con este enfoque, las nuevas vacunas sólo incluyen algunas moléculas (nativas o recombinantes), parte de éstas (péptidos sintéticos) o en su defecto, anticuerpos anti-idiotipo que mimetizan alguna estructura original en el patógeno. Entre los factores que han aumentado el interés para este enfoque, destaca la accesibilidad a las técnicas de biología molecular, que han permitido sobrepasar las limitaciones del enfoque tradicional. Prácticamente todas las vacunas que actualmente se emplean fueron desarrolladas antes del advenimiento de la biología molecular y aunque sólo se han podido obtener un número limitado de ellas, han significado un gran logro científico, que erradicó ya una enfermedad (viruela) y está en vías de hacer lo mismo con otras (tétanos, difteria, tosferina, poliomielitis, sarampión, etc.). No obstante, aún faltan muchas vacunas para prevenir un gran número de enfermedades infecciosas cuya trascendencia en la salud puede ser muy seria como lo ejemplifica el avance epidémico del Síndrome de Inmunodeficiencia Adquirida. Se abordan los diferentes énfoques que varios investigadores han empleado para el desarrollo de las nuevas vacunas