Although the field of drug delivery systems (DDS) has undergone a critical leap in the past few decades, the main drawback of most potential drugs is the inability to achieve targeted effects. Generally, cancer treatment includes chemotherapy, surgery and radiation, but all three have limitations. Both radiation therapy, as well as surgical procedures, restrict themselves to a localized tumor. Chemotherapy is widely used for a variety of cancers, including distal cancers, through systemic use of anti-tumor drugs. However, it often destroys healthy cells and causes severe systemic toxicity. To prevent this systemic toxicity, new and accurate targeting mechanisms are needed for drug delivery.

Also, some promising drugs are often stopped during development because they cannot be properly delivered to target cells, tissues and organs. To address these challenges, virosomal technology has emerged as a novel and sophisticated delivery system to help scientists solve current problems and achieve effective results. Virosomes are specialized liposomes with a diameter of around 150 nm, consisting of monolayer or bilayer phospholipid membrane vesicles incorporating virus-derived proteins, which can be used as carries for cellular delivery of various macromolecules.

Several types of virosomes have been generated, such as virosomes based on influenza virus, hepatitis B virus, human immunodeficiency virus, Newcastle disease virus, and Sendai virus. Influenza virus is most commonly used for virosome production. Till now, virosomes have been widely used as carries for cancer treatment, gene delivery, and malaria therapy, and have made great achievements. Besides, non-influenza virosomes are being considered for HIV-1 vaccine research.

※ Cancer treatment
Several virosome-based agents with high safety profiles have been approved by the United States Food and Drug Administration (FDA) for use in humans. Virosomes are ideal vehicles for delivering immunogenic substances in host bodies due to their reciprocally reinforcing functions when used as vaccines. Virosome vaccines had been used in several preclinical studies and clinical trials for cancer treatment. For example, cervical cancer is one of the cancers that has been successfully treated by immunotherapy of virosome-formulated vaccines.

Besides, virosomes can deliver drugs specifically to the target cancer cells by displaying appropriate molecules (such as antibodies or affibodies) on their surface. Even tumor-specific monoclonal antibody fragments (Fab) can be attached to virosomes to direct the carrier to selected tumor cells.

※ Gene delivery
Virosomes are a chemical DNA vaccine delivery tool. These vesicular DNA delivery moieties are similar to liposomes except for the inclusion of viral envelope proteins. These proteins (e.g., influenza hemagglutinin) render virosomes similar to native enveloped viruses and label them for fusion into target cells. They also protect virosomes from degradation and fusion or interaction with the cell membrane.

※ Malaria therapy
Malaria, caused by plasmodium falciparum, remains a major public health threat, especially among children and pregnant women in Africa. An effective malaria vaccine would be a valuable tool to reduce the disease burden and could contribute to elimination of malaria in some regions of the world. The concept of using antigen-loaded influenza virosomes for vaccination against malaria in humans has already been clinically validated by a virosomal formulation that combines optimized peptidomimetics derived from two effectors (circumsporozoite protein (CSP) and the apical membrane antigen 1 (AMA-1)). The virosome containing malarial vaccine is formulated with antimalarial peptides, showing superior tolerability and greater immune responses.

Author's Bio: 

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