Ancient West African foragers in the context of African population history.

Our knowledge of ancient human population structure in sub-Saharan Africa, particularly prior to the advent of food production, remains limited. Here we report genome-wide DNA data from four children-two of whom were buried approximately 8,000 years ago and two 3,000 years ago-from Shum Laka (Cameroon), one of the earliest known archaeological sites within the probable homeland of the Bantu language group1-11. One individual carried the deeply divergent Y chromosome haplogroup A00, which today is found almost exclusively in the same region12,13. However, the genome-wide ancestry profiles of all four individuals are most similar to those of present-day hunter-gatherers from western Central Africa, which implies that populations in western Cameroon today-as well as speakers of Bantu languages from across the continent-are not descended substantially from the population represented by these four people. We infer an Africa-wide phylogeny that features widespread admixture and three prominent radiations, including one that gave rise to at least four major lineages deep in the history of modern humans.

First early hominin from central Africa (Ishango, Democratic Republic of Congo).

Despite uncontested evidence for fossils belonging to the early hominin genus Australopithecus in East Africa from at least 4.2 million years ago (Ma), and from Chad by 3.5 Ma, thus far there has been no convincing evidence of Australopithecus, Paranthropus or early Homo from the western (Albertine) branch of the Rift Valley. Here we report the discovery of an isolated upper molar (#Ish25) from the Western Rift Valley site of Ishango in Central Africa in a derived context, overlying beds dated to between ca. 2.6 to 2.0 Ma. We used µCT imaging to compare its external and internal macro-morphology to upper molars of australopiths, and fossil and recent Homo. We show that the size and shape of the enamel-dentine junction (EDJ) surface discriminate between Plio-Pleistocene and post-Lower Pleistocene hominins, and that the Ishango molar clusters with australopiths and early Homo from East and southern Africa. A reassessment of the archaeological context of the specimen is consistent with the morphological evidence and suggest that early hominins were occupying this region by at least 2 Ma.

Surface-expressed viral proteins in feline infectious peritonitis virus-infected monocytes are internalized through a clathrin- and caveolae-independent pathway.

Infection with feline infectious peritonitis virus (FIPV), a feline coronavirus, frequently leads to death in spite of a strong humoral immune response. In previous work, we reported that infected monocytes, the in vivo target cells of FIPV, express viral proteins in their plasma membranes. These proteins are quickly internalized upon binding of antibodies. As the cell surface is cleared from viral proteins, internalization might offer protection against antibody-dependent cell lysis. Here, the internalization and subsequent trafficking of the antigen-antibody complexes were characterized using biochemical, cell biological and genetic approaches. Internalization occurred through a clathrin- and caveolae-independent pathway that did not require dynamin, rafts, actin or rho-GTPases. These findings indicate that the viral antigen-antibody complexes were not internalized through any of the previously described pathways. Further characterization showed that this internalization process was independent from phosphatases and tyrosine kinases but did depend on serine/threonine kinases. After internalization, the viral antigen-antibody complexes passed through the early endosomes, where they resided only briefly, and accumulated in the late endosomes. Between 30 and 60 min after antibody addition, the complexes left the late endosomes but were not degraded in the lysosomes. This study reveals what is probably a new internalization pathway into primary monocytes, confirming once more the complexity of endocytic processes.

Clathrin- and caveolae-independent entry of feline infectious peritonitis virus in monocytes depends on dynamin.

Feline infectious peritonitis virus (FIPV), a coronavirus that causes a lethal chronic disease in cats, enters feline monocytes via endocytosis. In this study, the pathway of internalization is characterized by evaluating the effect of chemical inhibitors and/or expression of dominant-negative (DN) proteins on the percentage of internalized virions per cell and infection. Further, co-localization studies were performed to determine the involvement of certain cellular internalization proteins. FIPV is not internalized through a clathrin-mediated pathway, as chlorpromazine, amantadine and DN eps15 did not influence virus uptake and FIPV did not co-localize with clathrin. The caveolae-mediated pathway could be excluded based on the inability of genistein and DN caveolin-1 to inhibit virus uptake and lack of co-localization between FIPV and caveolin-1. Dynamin inhibitory peptide and DN dynamin effectively inhibited virus internalization. The inhibitor strongly reduced uptake to 20.3+/-1.1% of uptake in untreated cells. In the presence of DN dynamin, uptake was 58.7+/-3.9% relative to uptake in untransduced cells. Internalization of FIPV was slightly reduced to 85.0+/-1.4 and 87.4+/-6.1% of internalization in control cells by the sterol-binding drugs nystatin and methyl-beta-cyclodextrin, respectively. Rho GTPases were inhibited by Clostridium difficile toxin B, but no effect was observed. These results were confirmed with infection studies showing that infection was not influenced by chlorpromazine, amantadine and genistein, but was significantly reduced by dynamin inhibition and nystatin. In conclusion, these results indicate that FIPV enters monocytes through a clathrin- and caveolae-independent pathway that strongly depends on dynamin and is slightly sensitive to cholesterol depletion.

Attachment and internalization of feline infectious peritonitis virus in feline blood monocytes and Crandell feline kidney cells.

In this study, kinetics of attachment and internalization of feline infectious peritonitis virus (FIPV) serotype I strain Black and serotype II strain 79-1146 were determined in feline monocytes from two cats and in Crandell feline kidney (CrFK) cells. Attached FIPV I (Black) particles were observed on almost all monocytes. Within 1 h, 17 particles were bound per cell and, within 1 min, 89 % of the bound particles were internalized. For FIPV II (79-1146), attachment was observed on 66 and 95 % of all monocytes from the two cats. After 1 h, respectively five and 20 particles were bound per cell (all cells considered). Within 1 min, 60 % of the bound particles were internalized. Internalization in monocytes was efficient and proceeded via endocytosis. In CrFK cells, attachment and internalization were less efficient, especially for FIPV I (Black), so this cell line is not suitable for studying FIPV entry.

Feline infectious peritonitis virus-infected monocytes internalize viral membrane-bound proteins upon antibody addition.

Feline infectious peritonitis virus (FIPV) may cause a highly lethal infection in cats, in spite of a usually strong humoral immune response. Antibodies seem unable to identify infected cells and mediate antibody-dependent cell lysis. In this study, the effect of antibodies on Feline coronavirus (FCoV)-infected monocytes was investigated. Upon addition of FCoV-specific antibodies, surface-expressed viral proteins were internalized through a highly efficient process, resulting in cells without visually detectable viral proteins on their plasma membrane. The internalization was also induced by mAbs against the Spike and Membrane proteins, suggesting that both proteins play a role in the process. The internalization did not occur spontaneously, as it was not observed in cells incubated with medium or non-specific antibodies. Further, the internalization could not be reproduced in feline cell lines, indicating its cell-type specificity. This study sheds new light on the immune-evasive nature of FIPV infections.