A pharmaceutical composition for use in treating of preventing an infection caused by a pathogen or toxicity from exposure to a toxin, the composition comprising immunoprotective primary mesenchymal stem cells (IP-MSC) that episomally express multiple immunoreactive polypeptides that specifically target a pathogen or toxin; the IP-MSC being transfected with one or more episomal vectors encoding multiple expressible immunoreactive polypeptides that specifically target the pathogen or toxin; wherein each immunoreactive polypeptide comprises an amino acid sequence from an antigen-binding region of a neutralizing antibody specific for an antigen produced by the pathogen or specific for the toxin, or an amino acid sequence of a variant of the antigen-binding region sequence comprising one or more substitutions in the amino acid sequence thereof and sharing at least about 50% sequence identity with the antigen-binding region sequence; the antigen-binding region sequence or variant thereof being arranged to specifically bind to and neutralize the pathogen or toxin; and wherein the episomal vector optionally includes an inducible apoptosis gene, wherein the immunoreactive polypeptides are selected from a full-length antibody, an antibody single-chain variable fragment (ScFV), a monovalent antibody antigen-binding fragment (Fab), a divalent antibody antigen-binding fragment (F(ab') 2), a diabody, and a tribody, and optionally wherein the IP-MSC also express one or more other immunomodulating agents, wherein the one or more immunomodulating agents are selected from interleukins and interferons; optionally wherein the pathogen is a viral pathogen, a bacterial pathogen, a single-celled parasitic pathogen, or a multicellular parasitic pathogen; optionally wherein the pathogen is a viral pathogen selected from the group consisting of: an adenovirus; a papillomavirus; a hepadnavirus; a parvovirus; a pox virus; Epstein-Barr virus; cytomegalovirus; a herpes simplex virus; roseolovirus; varicella zoster virus; a filovirus; a paramyxovirus; an orthomyxovirus; a rhabdovirus; an arenavirus; a coronavirus; a human enterovirus; hepatitis A virus; a human rhinovirus; polio virus; a retrovirus; a rotavirus; a flavivirus; a hepacivirus; and rubella virus; optionally wherein the pathogen is a bacterial pathogen from a genus selected from the group consisting of: Bacillus; Bordetella; Borrelia; Brucella; Burkholderia; Campylobacter; Chlamydia, Chlamydophila; Clostridium; Corynebacterium; Enterococcus; Escherichia; Francisella; Haemophilus; Helicobacter; Legionella; Leptospira; Listeria; Mycobacterium; Mycoplasma; Neisseria; Pseudomonas; Rickettsia; Salmonella; Shigella; Staphylococcus; Streptococcus; Treponema; Vibrio; and Yersinia; optionally wherein the pathogen is a parasitic pathogen selected from the group consisting of: Acanthamoeba; Anisakis; Ascaris lumbricoides; Balantidium coli; Cestoda (tapeworm); Chiggers; Cochliomyia hominivorax; Entamoeba histolytica; Fasciola hepatica; Giardia lamblia; Hookworm; Leishmania; Linguatula serrata, Liver fluke; Loa loa; Paragonimus (lung fluke); Pinworm; Plasmodium falciparum; Schistosoma; Strongyloides stercoralis; Toxoplasma gondii; Trypanosoma; Whipworm; and Wuchereria bancrofti; and optionally wherein the episomal vector comprises an Epstein-Barr Virus nuclear antigen 1 (EBVNA1) expression cassette. optionally wherein the pathogen is a viral pathogen, a bacterial pathogen, a single-celled parasitic pathogen, or a multicellular parasitic pathogen; optionally wherein the pathogen is a viral pathogen selected from the group consisting of: an adenovirus; a papillomavirus; a hepadnavirus; a parvovirus; a pox virus; Epstein-Barr virus; cytomegalovirus; a herpes simplex virus; roseolovirus; varicella zoster virus; a filovirus; a paramyxovirus; an orthomyxovirus; a rhabdovirus; an arenavirus; a coronavirus; a human enterovirus; hepatitis A virus; a human rhinovirus; polio virus; a retrovirus; a rotavirus; a flavivirus; a hepacivirus; and rubella virus; optionally wherein the pathogen is a bacterial pathogen from a genus selected from the group consisting of: Bacillus; Bordetella; Borrelia; Brucella; Burkholderia; Campylobacter; Chlamydia, Chlamydophila; Clostridium; Corynebacterium; Enterococcus; Escherichia; Francisella; Haemophilus; Helicobacter; Legionella; Leptospira; Listeria; Mycobacterium; Mycoplasma; Neisseria; Pseudomonas; Rickettsia; Salmonella; Shigella; Staphylococcus; Streptococcus; Treponema; Vibrio; and Yersinia; optionally wherein the pathogen is a parasitic pathogen selected from the group consisting of: Acanthamoeba; Anisakis; Ascaris lumbricoides; Balantidium coli; Cestoda (tapeworm); Chiggers; Cochliomyia hominivorax; Entamoeba histolytica; Fasciola hepatica; Giardia lamblia; Hookworm; Leishmania; Linguatula serrata, Liver fluke; Loa loa; Paragonimus (lung fluke); Pinworm; Plasmodium falciparum; Schistosoma; Strongyloides stercoralis; Toxoplasma gondii; Trypanosoma; Whipworm; and Wuchereria bancrofti; and optionally wherein the episomal vector comprises an Epstein-Barr Virus nuclear antigen 1 (EBVNA1) expression cassette.