Immunization with Pneumocystis Antigen Pca1 Protects against Pneumonia
Despite effective chemoprophylaxis, life-threatening opportunistic Pneumocystis pneumonia (PcP) infection remains a significant problem. Since the demonstration 30 years ago that antibody to Pneumocystis glycoprotein A reduces organism burden, laboratories have investigated the vaccine potential of various antigens. This effort has been hindered by the host species specificity of Pneumocystis. Tesini et al. (e00850-16) identified a potential vaccine candidate, Pneumocystis cross-reactive antigen 1 (Pca1), that both protected mice against PcP and induced antibody that recognizes the human pathogen, P. jirovecii. Such cross-reactivity is highly unusual and suggests that the vaccine potential of Pca1 and its homolog in P. jirovecii should be determined.
See also the related commentary by Garvy (e00035-17).
Severity of Plasmodium falciparum Malaria Is Associated with Parasites Expressing P. falciparum Erythrocyte Membrane Protein 1 Binding to Human Endothelial Protein C Receptor
Infection with Plasmodium falciparum can be asymptomatic or cause severe or fatal malaria, most often in children who have not yet developed protective immunity. Malaria pathology is linked to parasite-mediated attachment of infected red blood cells to specific endothelial receptors on blood vessel walls. Mkumbaye et al. (e00841-16) studied expression of the polymorphic P. falciparum erythrocyte membrane protein 1 (PfEMP1) genes encoding parasite adhesion molecules and found that expression of PfEMP1, which binds human endothelial protein C receptor (EPCR), was associated with the increasing severity of malaria in Tanzanian children. These data suggest that the PfEMP1-EPCR interaction is key to malaria pathology and potentially to the onset of malaria pathogenesis.
Type III Effectors from Enteropathogenic Escherichia coli Have Distinct Antiapoptotic Roles
Enteropathogenic Escherichia coli (EPEC) utilizes a type III secretion system to translocate virulence effector proteins into enterocytes during infection. One such effector, NleB1, inhibits FAS ligand (FasL)-induced caspase-8 cleavage and apoptosis by modifying the mammalian signaling adapter protein FADD. Another effector is the caspase inhibitor NleF. Pollock et al. (e01071-16) investigated possible synergy between these two effectors and found that NleF also inhibited FasL-induced caspase-8 cleavage and apoptosis during EPEC infection. However, this complementarity was not observed during infection with the EPEC-like mouse pathogen Citrobacter rodentium, suggesting distinct roles for NleB1 and NleF in vivo.