Q.68 The oral polio vaccine (OPV) consists of
(A) live attenuated virus (B) killed virus
(C) viral toxin (D) viral capsid subunit
Oral Polio Vaccine (OPV) consists of live attenuated virus. This makes option (A) correct for the MCQ. OPV uses weakened poliovirus strains to safely mimic infection and build strong gut immunity.
Option Analysis
(A) Live attenuated virus: OPV contains live poliovirus strains (Sabin types 1, 2, 3) weakened by serial passage in non-human cells, losing neurovirulence but retaining replication in the gut for mucosal immunity.
(B) Killed virus: This describes IPV (Salk vaccine), inactivated by formalin; OPV is live and oral, unlike injected IPV.
(C) Viral toxin: Toxoids target bacterial exotoxins (e.g., tetanus); poliovirus has no toxin.
(D) Viral capsid subunit: Subunit vaccines use protein fragments (e.g., HPV); OPV delivers intact live virus, not just capsid parts.
The oral polio vaccine (OPV) consists of live attenuated virus, a cornerstone in global polio eradication efforts. Developed by Albert Sabin, OPV delivers weakened poliovirus strains via oral drops, inducing lifelong gut and systemic immunity without causing disease. Ideal for mass campaigns, it excels in resource-limited settings due to ease of administration and herd protection via fecal-oral shedding.
Vaccine Types Breakdown
| Vaccine Type | Composition | Examples | Key Feature |
|---|---|---|---|
| Live Attenuated | Weakened live pathogen | OPV, MMR | Strong mucosal immunity |
| Killed/Inactivated | Heat/chemically inactivated | IPV (Salk polio) | No replication risk |
| Toxoid | Inactivated toxin | Diphtheria | Targets virulence factor |
| Subunit | Protein fragments | HPV, Hep B | Capsid or antigen only |
OPV’s live attenuated polioviruses replicate locally in intestines, blocking wild-type transmission—unlike IPV, which focuses on humoral response. Rare risks include vaccine-derived polioviruses (VDPV) in low-vaccination areas.
CSIR NET Relevance
For competitive exams like CSIR NET Life Sciences, understanding OPV as live attenuated distinguishes it from IPV (killed). Attenuation via monkey kidney cells alters viral genome, reducing CNS tropism while preserving antigenicity. This MCQ tests vaccine classification in biotechnology/immunology sections.
