Provided is a set of viral vectors, comprising: a first viral vector that carries a first nucleic acid molecule encoding an envelope protein, and a second viral vector that carries a second nucleic acid molecule encoding a fusion protein, the fusion protein comprising: a single-chain antibody capable of binding to CD28 or CD3, and a C-terminal domain, comprising a transmembrane region and an intracellular region, of the envelope protein. The C terminal of the single-chain antibody is connected to the N terminal of the C-terminal domain of the envelope protein, and the envelope protein and the fusion protein are in a non-fusion form. Also provided are a method for obtaining a lentivirus and an obtained lentivirus, a method for introducing a lentivirus into an unactivated T lymphocyte, a method for expressing a target gene, a method for obtaining a CAR-T cell and an obtained CAR-T cell, a pharmaceutical composition, and a use thereof.

Provided for herein are viral particles comprising a heterologous viral glycoprotein and a targeting moiety, wherein the targeting moiety comprises a polypeptide comprising a formula of T-S.sub.1, wherein T is a target binding domain and S.sub.1 is a stalk portion. The stalk portion may comprise a variant Fe domain. The stalk portion may comprise a flexible polypeptide domain. The targeting moiety comprising the formula T-S.sub.1 may be incorporated into a viral particle to assist with targeting such particles to a specific cell type. Also provided for herein are compositions comprising the same, and methods of using the same.

Provided for herein are viral particles comprising a heterologous viral glycoprotein and a targeting moiety, wherein the targeting moiety comprises a polypeptide comprising a formula of T-S.sub.1, wherein T is a target binding domain and S.sub.1 is a stalk portion. The stalk portion may comprise a variant Fc domain. The stalk portion may comprise a flexible polypeptide domain. The targeting moiety comprising the formula T-S.sub.1 may be incorporated into a viral particle to assist with targeting such particles to a specific cell type. Also provided for herein are compositions comprising the same, and methods of using the same.

A nanoparticle comprising a cytoplasmic type citrus leprosis virus-like particle (CiLV-C) p29 protein coat and an optional agent encapsulated with the protein coat is provided herein. The nanoparticles are useful for the delivery of the agents to cells or tissues.