SUMMARY The high-mannose patch on HIV Env is a preferred target for broadly neutralizing antibodies (bnAbs), but to date, no vaccination regimen has elicited bnAbs against this region. Here, we present the development of a bnAb lineage targeting the high-mannose patch in an HIV-1 subtype-C-infected donor from sub-Saharan Africa. The Abs first acquired autologous neutralization, then gradually matured to achieve breadth. One Ab neutralized >47% of HIV-1 strains with only ~11% somatic hypermutation and no insertions or deletions. By sequencing autologous env, we determined key residues that triggered the lineage and participated in Ab-Env coevolution. Next-generation sequencing of the Ab repertoire showed an early expansive diversification of the lineage followed by independent maturation of individual limbs, several of them developing notable breadth and potency. Overall, the findings are encouraging from a vaccine standpoint and suggest immunization strategies mimicking the evolution of the entire high-mannose patch and promoting maturation of multiple diverse Ab pathways.

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Transcription and replication of influenza A virus are carried out in the nuclei of infected cells in the context of viral ribonucleoproteins (RNPs). The viral polymerase responsible for these processes is a protein complex composed of the PB1, PB2, and PA proteins. We previously identified a set of polymerase-associated cellular proteins by proteomic analysis of polymerase-containing intracellular complexes expressed and purified from human cells. Here we characterize the role of NXP2/MORC3 in the infection cycle. NXP2/MORC3 is a member of the Microrchidia (MORC) family that is associated with the nuclear matrix and has RNA-binding activity. Influenza virus infection led to a slight increase in NXP2/MORC3 expression and its partial relocalization to the cytoplasm. Coimmunoprecipitation and immunofluorescence experiments indicated an association of NXP2/MORC3 with the viral polymerase and RNPs during infection. Downregulation of NXP2/MORC3 by use of two independent short hairpin RNAs (shRNAs) reduced virus titers in low-multiplicity infections. Consistent with these findings, analysis of virus-specific RNA in high-multiplicity infections indicated a reduction of viral RNA (vRNA) and mRNA after NXP2/MORC3 downregulation. Silencing of NXP2/MORC3 in a recombinant minireplicon system in which virus transcription and replication are uncoupled showed reductions in cat mRNA and chloramphenicol acetyltransferase (CAT) protein accumulation but no alterations in cat vRNA levels, suggesting that NXP2/MORC3 is important for influenza virus transcription. IMPORTANCE Influenza virus infections appear as yearly epidemics Influenza viruses cause an acute respiratory disease that annually affects millions of people worldwide (Global Influenza Surveillance and Response System [GISRS] [http://www.who .int/influenza/gisrs_laboratory/en/]). The genome of influenza A viruses is about 13 kb long and consists of eight single-stranded negative-sense RNA segments. The viral proteome includes 10 viral proteins that have been studied extensively (1) and another 8 proteins, probably accessory proteins, that were identified more recently (reviewed in reference 2). The transcription and replication of influenza viruses occur in the nuclei of infected cells and are mediated by the viral polymerase, a heterotrimer composed of the PB1, PB2, and PA subunits, in the context of viral ribonucleoprotein complexes (RNPs) (3; reviewed in references 4 to 7). The virus recruits host cell factors to help carry out these processes, and in some specific cases, their roles in virus replication have been determined (reviewed in references 4 and 8 to 10). In one such study, we identified the nuclear matrix NXP2 protein as a factor associated with influenza virus polymerase in vivo by proteomic analysis of recombinant purified polymerase complexes (11). Since influenza virus RNA synthesis is connected to the nuclear matrix (12, 13), we decided to further characterize the role of NXP2 in the virus infection cycle.The NXP2 protein (also called MORC3, ZCW...