Table 1.
Key features of replicating and non-replicating vaccine vectors
| Viral vector | Type | Insert | Advantages | Disadvantages |
|---|---|---|---|---|
| Adenovirus | Non-replicating; ds DNA | 7–8 kb | Common features: | Prior immunity to Ad5 |
| Targets mucosal inductive sites | High doses needed to elicit immunity | |||
| Infects dividing, non-dividing, and dendritic cells | ||||
| No integration | ||||
| Physically and genetically stable | ||||
| Specific for non-replicating vector: | ||||
| Safe | ||||
| Long history of gene therapy use | ||||
| Multiple serotypes and chimeric forms | ||||
| Adenovirus | Replicating ds DNA | 3–4 kb | Specific for replicating vector: | Small insert size |
| Common features above | Concern for intranasal administration | |||
| Low dose, mucosal delivery | ||||
| Persistent immunity | ||||
| Induction of immune modulators | ||||
| Safe as an oral vaccine | ||||
| Adeno-associated virus | Non-replicating; ss DNA | <5 kb | Resistant to acid; physically stable | Difficult production uses helper virus |
| Alternate serotypes available | Possible integration | |||
| Tropic for dendritic cells | Prior immunity to prevalent AAV2 | |||
| Non-pathogenic | ||||
| Alphavirus | Non-replicating; +ss RNA | <8 kb | No integration | Safety concerns regarding VEE |
| Does not elicit anti-vector immunity | Difficult to produce | |||
| Targets dendritic cells | ||||
| Highly immunogenic | ||||
| Herpesvirus | Non-replicating; ds DNA | <50 kb | Infects many cell types; targets mucosa | Prior immunity |
| Durable immunity | Lesser immunogenicity | |||
| Induces Th1 responses | Difficult to manufacture | |||
| Measles virus | Replicating; -ss RNA | >5 kb | Persistent immunity | Prior immunity |
| Infects dendritic cells, macrophages | ||||
| No integration; genetic stability | ||||
| Poxviruses: Vaccinia | Replicating; ds DNA | >10 kb | Excellent immunogenicity with history of eradicating smallpox | Safety concerns in immune compromised |
| Poxviruses: NYVAC; MVA | Non-replicating; ds DNA | >10 kb | Excellent immunogenicity; more immunogenic than avian poxviruses | Prior immunity |
| Poxviruses: ALVAC; FPV | Non-replicating; ds DNA | >10 kb | No prior immunity | Less immunogenic than mammalian poxviruses |
| Vesicular stomatitis virus | Replicating; -ss RNA | >5 kb | No integration; high level expression | Safety; potentially neurovirulent |
| Ease of production | Attenuated forms less immunogenic | |||
| No prior immunity | ||||
| Mucosal administration | ||||