Synergism/complementarity of recombinant adenoviral vectors and other vaccination platforms during induction of protective immunity against malaria

The lack of immunogenicity of most malaria antigens and the complex immune responses required for achieving protective immunity against this infectious disease have traditionally hampered the development of an efficient human malaria vaccine. The current boom in development of recombinant viral vectors and their use in prime-boost protocols that result in enhanced immune outcomes have increased the number of malaria vaccine candidates that access pre-clinical and clinical trials. In the frontline, adenoviruses and poxviruses seem to be giving the best immunization results in experimental animals and their mutual combination, or their combination with recombinant proteins (formulated in adjuvants and given in sequence or being given as protein/virus admixtures), has been shown to reach unprecedented levels of anti-malaria immunity that predictably will be somehow reproduced in the human setting. However, all this optimism was previously seen in the malaria vaccine development field without many real applicable results to date. We describe here the current state-of-the-art in the field of recombinant adenovirus research for malaria vaccine development, in particular referring to their use in combination with other immunogens in heterologous prime-boost protocols, while trying to simultaneously show our contributions and point of view on this subject.

Construction of a recombinant adenovirus co-expressing truncated human prostate-specific membrane antigen and mouse 4-1BBL genes and its effect on dendritic cells

Our aim was to construct a recombinant adenovirus co-expressing truncated human prostate-specific membrane antigen (tPSMA) and mouse 4-1BBL genes and to determine its effect on dendritic cells (DCs) generated from bone marrow suspensions harvested from C57BL/6 mice for which the effect of 4-1BBL on DCs is not clear, especially during DCs processing tumor-associated antigen. Replication deficient adenovirus AdMaxTM Expression System was used to construct recombinant adenovirus Ad-tPSMA-internal ribosome entry site-mouse 4-1BBL (Ad-tPSMA-IRES-m4-1BBL) and Ad-enhanced green fluorescent protein. Day 7 proliferating DC aggregates generated from C57BL/6 mice were collected as immature DCs and further mature DCs were obtained by lipopolysaccharide activated immature DCs. After DCs were exposed to the recombinant adenovirus with 250 multiplicity of infection, the expression of tPSMA and m4-1BBL proteins were detected by Western blot, and the apoptosis and phenotype of DCs were analyzed by flow cytometry. Cytokines (IL-6 and IL-12) in the supernatant were detected by enzyme-linked immunosorbent assay (ELISA). Proliferation of T cells was detected by allogeneic mixed lymphocyte reactions. The tPSMA and m4-1BBL proteins were expressed correctly. The apoptosis rate of DCs transfected with Ad-tPSMA-IRES-m4-1BBL was 14.6 percent, lower than that of control DCs. The expression of co-stimulatory molecules [CD80 (81.6 ± 5.4 percent) and CD86 (80.13 ± 2.81 percent)] up-regulated in Ad-tPSMA-IRES-m4-1BBL-pulsed DCs, and the level of IL-6 (3960.2 ± 50.54 pg/mL) and IL-12 (249.57 ± 12.51 pg/mL) production in Ad-tPSMA-IRES-m4-1BBL-transduced DCs were significantly higher (P < 0.05) than those in control DCs. Ad-tPSMA-IRES-m4-1BBL induced higher T-cell proliferation (OD450 = 0.614 ± 0.018), indicating that this recombinant adenovirus can effectively enhance the activity of DCs.

Investigation of circulating anti-coxsackie B, anti- polio and anti-adeno IgG in newly diagnosed T1DM children

Viruses may be involved in the pathogenesis of Type 1 Diabetes Mellitus [T1DM], either through direct beta-cell infection or as triggers of autoimmunity. To investigate the presence of specific anti- viral IgG antibodies for Coxsackie virus type B [CVB5], Poliovirus, and Adenovirus which proposed to be involved in the etiology of T1DM. A total of 60 Iraqi T1DM children were included in the present study. They were new onset of the disease [diagnosis was from one week up to five months]. For the purpose of comparisons, 50 apparently healthy control subjects were selected. Serum IgG against Coxsackie virus type B[5], Adenovirus type 3, 4, and 7, and Poliovaccin Trivalent were detected quantitatively with an indirect ELISA. High proportion of anti-CVB5 IgG [20%][p<0.05] and anti- Polio IgG [31.67%] were found in T1DM children compared to controls [8%, 26% respectively], while anti- Adeno IgG were detected in diabetic patients only [6.67%][p<1.0001]

Recombinant viruses as vaccines against viral diseases

Vaccine approaches to infectious diseases are widely applied and appreciated. Amongst them, vectors based on recombinant viruses have shown great promise and play an important role in the development of new vaccines. Many viruses have been investigated for their ability to express proteins from foreign pathogens and induce specific immunological responses against these antigens in vivo. Generally, gene-based vaccines can stimulate potent humoral and cellular immune responses and viral vectors might be an effective strategy for both the delivery of antigen-encoding genes and the facilitation and enhancement of antigen presentation. In order to be utilized as a vaccine carrier, the ideal viral vector should be safe and enable efficient presentation of required pathogen-specific antigens to the immune system. It should also exhibit low intrinsic immunogenicity to allow for its re-administration in order to boost relevant specific immune responses. Furthermore, the vector system must meet criteria that enable its production on a large-scale basis. Several viral vaccine vectors have thus emerged to date, all of them having relative advantages and limits depending on the proposed application, and thus far none of them have proven to be ideal vaccine carriers. In this review we describe the potential, as well as some of the foreseeable obstacles associated with viral vaccine vectors and their use in preventive medicine.

Enzyme linked immunosorbent assay: determination of anti-adenovirus antibodies in an infant population

Com a finalidade de encontrar um ensaio preciso para a detecçäo de anticorpos anti-adenovírus, o teste ELISA recentemente padronizado foi compardo à inmunofluorescência indireta (IFI) e à fixaçäo de complemento (FC). Após testar 58 sóros, o ELISA demonstrou maior sensibilidade do que a IFI e a FC, que mostraram sensibilidades relativas de 94% e 63%, respectivamente. A falta de um padräo universal näo permitiu alcançar conclusöes definitivas quanto à especificidade dos ensaios. Além disso, o ELISA foi utilizado para estabelecer a prevalência de anticorpos anti-adenovírus em 116 crianças entre 1 e 24 meses de idade (média 7.28). Os dados mostraram que os anticorpos maternos desaparecem ao redor dos 5 a 6 meses de idade e que mais de 80% das crianças tinham sido infectadas antes dos 10 meses de idade