Formylglycine-Generating Enzyme-Like Proteins Constitute a Novel Family of Widespread Type VI Secretion System Immunity Proteins.

Competition is a critical aspect of bacterial life, as it enables niche establishment and facilitates the acquisition of essential nutrients. Warfare between Gram-negative bacteria is largely mediated by the type VI secretion system (T6SS), a dynamic nanoweapon that delivers toxic effector proteins from an attacking cell to adjacent bacteria in a contact-dependent manner. Effector-encoding bacteria prevent self-intoxication and kin cell killing by the expression of immunity proteins, which neutralize effector toxicity by specifically binding their cognate effector and either occluding its active site or preventing the structural rearrangements necessary for effector activation. In this study, we investigate Tsi3, a previously uncharacterized T6SS immunity protein present in multiple strains of the human pathogen Acinetobacter baumannii. We show that Tsi3 is the cognate immunity protein of an antibacterial effector of unknown function, Tse3. Our bioinformatic analyses indicate that Tsi3 homologs are widespread among Gram-negative bacteria, often encoded within T6SS effector-immunity modules. Surprisingly, we found that Tsi3 homologs are predicted to possess a characteristic formylglycine-generating enzyme (FGE) domain, which is present in various enzymatic proteins. Our data show that Tsi3-mediated immunity is dependent on Tse3-Tsi3 protein-protein interactions and that Tsi3 homologs from various bacteria do not provide immunity against nonkin Tse3. Thus, we conclude that Tsi3 homologs are unlikely to be functional enzymes. Collectively, our work identifies FGE domain-containing proteins as important mediators of immunity against T6SS attacks and indicates that the FGE domain can be coopted as a scaffold in multiple proteins to carry out diverse functions. IMPORTANCE Despite the wealth of knowledge on the diversity of biochemical activities carried out by T6SS effectors, comparably little is known about the various strategies that bacteria employ to prevent susceptibility to T6SS-dependent bacterial killing. Our work establishes a novel family of T6SS immunity proteins with a characteristic FGE domain. This domain is present in enzymatic proteins with various catalytic activities. Our characterization of Tsi3 expands the known functions carried out by FGE-like proteins to include defense during T6SS-mediated bacterial warfare. Moreover, it highlights the evolution of FGE domain-containing proteins to carry out diverse biological functions.

Cryptosporidium sp. E isospora belli en pacientes con diarrea, infectados por el virus de inmunodeficiencia humana, Maracaibo 1993 / Cryptosporidium sp and isospora belli in patients with diarrhea infected with human immunodeficiency virus. Maracaibo 1993

Para investigar la prevalencia de Cryptosporidium sp e isospora belli entre pacientes con infección por el Virus de Inmunodeficiencia Humana (VIH) y diarrea, se estudiaron 20 pacientes VIH seropositivos con evacuaciones líquidas o semilíquidas, en números de 3 ó más por día, con 7 ó más días de evolución. A cada uno se le practicó examen de heces al fresco y con la coloración de Zielh Neelsen (ZN) modificada, realizándose estos examenes en forma seriada según los resultados, e individualizando cada caso para la solicitud de otros estudios. De los 20 pacientes, la mayoría fueron del sexo masculino y de 25 a 44 años de edad, de ellos 11 (55.5 por ciento) presentaron coccidios asociados a la diarrea. Entre los pacientes con coccidios, 8 presentaron Cryptosporidium sp y a 3 se les encontró Isospora belli correspondiéndole el 40 por ciento y 15 por ciento respectivamente del total. La observación del primer examen de heces al fresco y/o con la tinción de ZN modificada, permitió el diagnóstico en 7 de los pacientes con Cryptosporidium sp y en 2 de los 3 con Isospora belli. En algunos de los casos, Criptosporidiosis (75 por ciento) e Isosporiasis (100 por ciento) fueron la primera infección oportunista. Condiciones sanitarias inadecuadas parecen ser un factor de riesgo importante

Infección por virus de inmunodeficiencia humana (VIH-1) en donantes de sangre: Maracaibo, Edo. Zulia-Venezuela / Infection by human immunodeficiency virus (HIV-1) in blood donors: Maracaibo State Zulia-Venezuela

Fueron procesados 16.489 sueros sanguíneos por los Métodos de Inmunoanálisis Enzimático ELISA Abbot Laboratorio y Western Blot, para la investigación de anticuerpos contra el Virus de Inmunodeficiencia Humana (VIH-1) en donantes de sangre del Instituto Hematólogico de Occidente (IHO) Maracaibo Edo. Zulia, Venezuela durante los meses de enero-diciembre 1993; obteniéndose 16 casos positivos (0.097 por ciento)