The study investigates the nuclear entry of HIV-1 capsids in primary human macrophages, focusing on the interaction between the capsid and the nuclear pore complex (NPC). The authors used super-resolution microscopy, cryo-electron tomography, and molecular simulations to analyze the process. Key findings include: 1. **Accumulation at Nuclear Pores**: HIV-1 capsids accumulate at nuclear pores, suggesting that passage through the NPC is a rate-limiting step in early HIV-1 replication. 2. **Morphological Integrity**: Capsids remain morphologically intact during their passage through the NPC, with a cone-shaped structure facilitating entry. 3. **Cyclophilin A Loss**: Cyclophilin A (CypA), a cytosolic protein, is stripped off the capsid upon entering the NPC. 4. **NPC Cracking**: The NPC scaffold frequently cracks during capsid passage, consistent with computer simulations indicating the need for NPC widening. 5. **Molecular Dynamics Simulations**: Simulations support the idea that NPC cracking facilitates capsid passage by relieving steric barriers. 6. **Model for Nuclear Entry**: A model is proposed where capsids dock to the cytoplasmic face of the NPC, lose CypA, and then pass through the NPC by cracking its scaffold. These findings provide insights into the structural and functional aspects of HIV-1 capsid entry into the nucleus, highlighting the importance of NPC dynamics and the role of specific proteins in this process.The study investigates the nuclear entry of HIV-1 capsids in primary human macrophages, focusing on the interaction between the capsid and the nuclear pore complex (NPC). The authors used super-resolution microscopy, cryo-electron tomography, and molecular simulations to analyze the process. Key findings include: 1. **Accumulation at Nuclear Pores**: HIV-1 capsids accumulate at nuclear pores, suggesting that passage through the NPC is a rate-limiting step in early HIV-1 replication. 2. **Morphological Integrity**: Capsids remain morphologically intact during their passage through the NPC, with a cone-shaped structure facilitating entry. 3. **Cyclophilin A Loss**: Cyclophilin A (CypA), a cytosolic protein, is stripped off the capsid upon entering the NPC. 4. **NPC Cracking**: The NPC scaffold frequently cracks during capsid passage, consistent with computer simulations indicating the need for NPC widening. 5. **Molecular Dynamics Simulations**: Simulations support the idea that NPC cracking facilitates capsid passage by relieving steric barriers. 6. **Model for Nuclear Entry**: A model is proposed where capsids dock to the cytoplasmic face of the NPC, lose CypA, and then pass through the NPC by cracking its scaffold. These findings provide insights into the structural and functional aspects of HIV-1 capsid entry into the nucleus, highlighting the importance of NPC dynamics and the role of specific proteins in this process.