No abstract

Spinal cord injury in adult mammals causes atrophy or loss of axotomized neurons. We have previously found that the product of the antiapoptotic gene Bcl-2, delivered by intraspinal injection of a DNA plasmid, reduces atrophy and loss of axotomized Clarke's nucleus neurons in adult rats. Here we studied whether the same treatment protects axotomized red nucleus (RN) neurons. Two months after the right dorsolateral funiculus was ablated in adult Sprague-Dawley rats by C3/C4 subtotal hemisection, there was approximately 48% loss of RN neurons in the magnocellular portion of the RN contralateral to the lesion and atrophy of many surviving neurons. When a DNA plasmid encoding the human Bcl-2 gene and the bacterial reporter gene LacZ, complexed with cationic lipids, was injected just rostral to the subtotal hemisection site, 87% of RN neurons survived, and there was partial, but robust, protection from atrophy. These and our previous results indicated that intraspinal administration of the Bcl-2 gene can prevent retrograde cell loss and reduce atrophy of axotomized RN and Clarke's nucleus neurons in adult rats and provide an effective means to rescue neurons whose survival depends on different growth factors.

TRIM5α and MxB are known as restriction factors that inhibit the early step of intracellular HIV-1 replication cycle. Both factors are believed to interact with the incoming virus core to suppress HIV-1 infection. The extreme diversity of HIV-1 is thought to be a consequence of its propensity to mutate to escape immune responses and host restriction factors. We recently determined the capsid sequences for 144 HIV-1 CRF01_AE viruses obtained in Thailand from 2005 to 2011. In this study, we further analyzed the amino acid variations among the capsid sequences of 204 HIV-1 CRF01_AE obtained in Thailand and China, including 84 of the aforementioned 144 viruses, to detect mutations permitting escape from restriction by host factors. We found a characteristic combination of E79D, V83T, and H87Q in sequences from Chinese viruses and subsequently showed that this combination conferred partial resistance to MxB. Interestingly, this combination conferred resistance to human TRIM5α as well. The H87Q mutation alone conferred resistance to MxB in the CRF01_AE background, but not in subtype B virus. In contrast, the H87Q mutation alone conferred resistance to human TRIM5α in both the CFR01_AE and subtype B backgrounds. BLAST analysis revealed the presence of the E79D, V83T, and H87Q combination in CRF01_AE viruses isolated not only in China but also in many other countries. Although the mechanistic details as well as precise role of MxB antiviral activity in infected individuals remain to be clarified, our data suggest an interaction between MxB and the HIV-1 capsid in vivo.