Cell culture — Which of the following are continuous (immortal) human cell lines used in virology labs?

Introduction / Context:
Choosing the right cell line is critical for virus isolation and research. Continuous (immortal) lines divide indefinitely under culture, unlike primary or semi-continuous diploid strains that senesce after limited passages.

Given Data / Assumptions:

• HeLa (cervical carcinoma), HEp-2 (laryngeal/epithelial carcinoma), and KB (epithelial carcinoma) are widely cited.
• Continuous lines are aneuploid and immortal.

Concept / Approach:
HeLa, HEp-2, and KB are classic continuous human lines, commonly permissive for a range of human viruses. In contrast, semi-continuous diploid lines include WI-38 and MRC-5, which have finite lifespans and near-diploid karyotypes.

Step-by-Step Solution:

Verification / Alternative check:
Standard virology manuals categorize these three as continuous lines used for viral culture and research.

Why Other Options Are Wrong:

• HeLa alone, HEp-2 alone, or KB alone: each is true but incomplete; the grouping answer captures all correct cases.

Common Pitfalls:
Confusing continuous lines with human diploid strains like WI-38/MRC-5; the latter are not immortal.

Final Answer:
All of these