Question:medium
Which virus among the following is least likely to cross the placenta?
Which virus among the following is least likely to cross the placenta?
Show Hint
Neonatal infection here happens mainly during delivery, not in the womb.
Updated On: Jun 24, 2026
- Rubella
- Herpes simplex
- HIV
- HBV
Show Solution
The Correct Option is B
Solution and Explanation
Transplacental (vertical, in-utero) viral transmission is the focus here. Rubella is the prototype TORCH agent and crosses the placenta with ease, producing the well known congenital rubella triad. HIV reaches the fetus across the placenta during pregnancy and also during delivery and lactation, so it is not the least likely. Hepatitis B virus can infect the fetus in utero, though most neonatal infection occurs at the time of birth, so it too is capable of crossing. Herpes simplex virus behaves differently: the overwhelming majority of neonatal herpes results from direct contact with virus shed in the genital tract during vaginal delivery, and true intrauterine transplacental herpes is uncommon. Comparing the four options, HSV stands out as the agent least dependent on, and least likely to use, the transplacental route.
\[\boxed{\text{Herpes simplex}}\]
\[\boxed{\text{Herpes simplex}}\]
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