Academic journal article Iranian Journal of Public Health

Molecular Cloning and Expression an 8-kDa Subunit of Antigen B from G1 Strain of Echinococcus Granulosus

Academic journal article Iranian Journal of Public Health

Molecular Cloning and Expression an 8-kDa Subunit of Antigen B from G1 Strain of Echinococcus Granulosus

Article excerpt


Hydatidosis or cystic echinococcosis, caused by the larval stage of the dog taeniid tapeworm Echinococcus granulosus, is a chronic, prevalent and classic zoonotic disease of important public health problem. This disease has a worldwide distribution, especially in countries with a common livestock industry, such as Mediterranean and Middle Eastern countries. It is endemic in some parts of Iran (1-6).

In life cycle of E. granulosus, with an indirect twohost, carnivores (mostly dogs) are definitive hosts and wide range of mammals including humans act as intermediate hosts. Hydatidosis in intermediate hosts results from accidental ingestion of tapeworm eggs passed into the environment with fae- ces from definitive hosts. Hydatid cysts (metacestodes) can be established in any internal organs, mainly liver and/or lungs, of intermediate hosts (7-9).

There are currently three treatment options for cystic echinococcosis: surgery, PAIR) Puncture, Aspiration, Injection and Re-aspiration), and chemotherapy. Each of these modalities has limitations depending on the specific case. Chemotherapy constitutes a non-invasive treatment but has limitations to use in patients with chronic liver diseases, with bone marrow depression and during pregnancy. Further, chemotherapy is ineffective in 40% of cases (10-13).

Surgery is the main treatment, and is only way to completely remove the hydatid cyst. Nevertheless, for many reasons such as operative mortality, complications (anaphylaxis), relapse, temporary and permanent contraindications to surgery such as difficulty to reach the lesion, poor status of the patient, refusal of certain patients to undergo surgery poor and lack medical facilities/structures, is not always feasible (2, 11, 13).

Because of the difficulty of diagnosis due to the long incubation period, the difficulty of treatment and the risks and complications of the disease, control and prevention is important (14). Hydatid control programs have been successful in Iceland and New Zealand, mostly based on health education, control or elimination of home slaughter of sheep and in countries like Argentina, Chile and Uruguay, control programs have been reduced infections in cattle, dogs and humans. Hydatid control programs have been successful only at the local level and therefor, the global distribution and the important public health problem of hydatid cyst has not changed seriously (10, 11). In many endemic areas, effective control of the disease is not available or not applicable. In addition, failure or cessation this programs in endemic are as can turn it into a hyper endemic areas (10).

Mathematical models show that the most effective way of combating hydatid cyst is a combination of vaccination intermediate host and anti-helminthic treatment of definitive host (13, 15, 16). Vaccination has been considered as one of the ways to prevent hydatidosis in recent decades. DNA vaccines, third generation vaccines, are plasmid that has been genetically engineered to produce specific protein/proteins (antigens) from a pathogen, that after inoculation are expressed by cellular machinery. Among the key features of these vaccines can be noted to elicit each the three arms of acquired immunity (CTLs, Abs, T helper) and the innate immune response, strong and lasting immune response, at room temperature resistant, easy storage and transport (17, 18).

Antigen B (AgB) in hydatid cyst fluid of E. granulosus is a polymeric lipoprotein of 160 kDa and a highly immunogenic major antigen. The antigen is comprised of a group of subunit monomers of approximately 8 kDa in molecular size. Molecular studies have demonstrated that AgB is encoded by a multigene family having at least five gene loci (B1-B5), each one consisting of several minor variants that could be grouped into five clades, corresponding to the genes EgAgB8/1, EgAgB8/2, EgAgB8/3, EgAgB8/4 and EgAgB8/5 (19-22).

The aim of the present study was to construct a pcDNA3. …

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