Escheriosomes entrapped DNA vaccine co-expressing Cu-Zn superoxide dismutase and IL-18 confers protection against Brucella abortus.

In the present study, we evaluated prophylactic prospective of liposome based DNA vaccine co-expressing Cu-Zn superoxide dismutase (SOD) along with interleukin-18 (IL-18) against experimental murine brucellosis. The immunization schedule involves liposome-mediated delivery of pVsod (encoding SOD of Brucella abortus) and pVIL18-sod (encoding IL-18 of mouse and SOD of B. abortus) DNA constructs. The data highlight potential of Escherichia coli lipid liposome (escheriosome) based DNA delivery vehicle to induce SOD specific humoral and cellular immune responses in the immunized mice. The co-expression of SOD along with IL-18 ensued in higher lymphoproliferative response and IFN-gamma production in comparison to the group of animals that were immunized with free form of SOD-DNA. Antibody response developed upon immunization with both DNA vaccines was of IgG2a type mainly. The results of the present study show that co-expression of IL-18 along with SOD polarized the antigen specific immune responses toward Th-1 direction, a desirable feature to control intracellular pathogens.

Escheriosome-mediated delivery of recombinant ribosomal L7/L12 protein confers protection against murine brucellosis.

Brucellosis is an important zoonotic disease that causes abortion in cattle and undulant fever, arthritis, endocarditis and meningitis in human. In spite of the fact that immunization could be an efficient measure to control brucellosis, not a single ideal vaccine against this important disease has been developed so far. In order to develop an effective vaccine against Brucella abortus (B. abortus), various protective immunodominant gene/protein products of the pathogen have been studied in combination with different adjuvants. For example, recombinant ribosomal protein L7/L12 (rL7/L12) although an interesting T-cell antigen, normally failed to evoke protective immune response when used in free form. In the present study we have demonstrated that Escherischia coli (E. coli) lipid liposome (escheriosome)-mediated cytosolic delivery of recombinant rL7/L12 protein can elicit strong immunological responses in the Balb/c mice. In contrast, egg PC/Chol liposome entrapped rL7/L12, in a manner similar to its free form, was found to impart relatively poor immune response. Furthermore, escheriosome entrapped rL7/L12 protein elicited high IgG2a isotype response suggestive of its relevance in imparting protection against brucellosis in mice. Altogether the present study is a clear indicative of the possible use of escheriosome-based delivery of rL7/L12 protein to induce protective immune responses against experimental murine brucellosis.

Liposomised recombinant ribosomal L7/L12 protein protects BALB/c mice against Brucella abortus 544 infection.

Brucella abortus, a facultative intracellular pathogen, is of tremendous zoonotic importance because of its ability to induce spontaneous abortion in cattle and other livestock. It is also known to cause persistent undulant fever, endocarditis, arthritis, osteomyelitis and meningitis in humans. The available vaccines against this dreadful infection suffer from limitations like short-term immunity, increased risk of hypersensitivity and low prophylactic index in the recipients. In the present study, we have demonstrated that liposomal form of a recombinant ribosomal L7/L12 protein, a B-T cell antigen of B. abortus, activates strong immune response in the host. In contrast, free antigen generates moderate immune response in the immunised animals. The liposomisation of rL7/L12 protein causes tremendous increase in cell-mediated immune response in terms of delayed type hypersensitivity, T-cell proliferation and up-regulation in type I cytokine expression, etc. Moreover, the liposome encapsulated antigen elicited stronger humoral immune response as compared to standard vaccine (S-19) or IFA-L7/L12 combination in the immunised animals. The effectiveness of liposome-based vaccine was also substantiated by better systemic clearance of bacterial load after challenging the animals with B. abortus 544 pathogen. The results of the present study suggest the potential of liposome-based rL7/L12 antigen as prospective and efficient candidate vaccine capable of eliciting both cell mediated as well as humoral immune responses against experimental murine brucellosis.

Co-administration of immunomodulator tuftsin and liposomised nystatin can combat less susceptible Candida albicans infection in temporarily neutropenic mice.

In order to develop a prospective chemotherapeutic agent against opportunistic infections, it is important to know that host factors such as degree of immunological debility as well as recovery of immune functions to normality may contribute significantly to a successful elimination of the pathogens. We demonstrated previously that concomitant delivery of antimicrobial agents and immunomodulators to the pathogen harbouring-host contributes to the complete elimination of the deep-seated fungal infections (aspergillosis and candidiasis) in animals with normal immune status. Considering that neutropenic hosts are the main targets of such infections, it can be argued about the potential of the immunomodulator-based therapy in subjects with non-functional immune system. To resolve the hypothesis, we studied the role of immunomodulator tuftsin against experimental murine candidiasis in temporarily neutropenic Balb/c mice. The neutropenic mice were challenged with an isolate of Candida albicans that was showing less susceptibility to both free and liposomised-amphotericin B. The co-administration of tuftsin increased the efficiency of liposomised-polyene antibiotics (nystatin and amphotericin B) against experimental murine candidiasis in immunocompromised Balb/c mice. Pretreatment with liposomised tuftsin prior to C. albicans infection clearly enhanced protection against candidiasis, suggesting a prophylactic role of tuftsin in normal and temporarily neutropenic animals.