Papers by Alejandro Cisneros
FEMS microbiology …, Jan 1, 1998
Dengue \iruses are arthropod-borne. single-stranded R N A viruses. AEdes oegjpri and Aedes nlh~pi... more Dengue \iruses are arthropod-borne. single-stranded R N A viruses. AEdes oegjpri and Aedes nlh~picrus are the principal \.ectors. In order to understand the molecular basis of dengue virus infections we explored the biochemical identity of dengue-? I D E S -2 ) \irus receptors in the Aedcs rrlhopicrrrs-deri\'ed cell line C6136. We show here that DEN-? interacts with two major pol!.peptides of 80 and 67 kDa. Polyclonal antK6136 membrane antibodies block DEN-2 binding to intact C6136 monolayers as \\.ell as to membrane extracts. Our results strongly suggest that the identified polypeptides are part of the DEN-?
Infection and immunity, Jan 1, 1995
Acquired cellular resistance against Mycobacterium avium complex (MAC) infections involves the in... more Acquired cellular resistance against Mycobacterium avium complex (MAC) infections involves the induction of Th1 type gamma interferon (IFN-gamma)-producing T cells. Interleukin-12 (IL-12) is a cytokine involved in the control of IFN-gamma production by T cells and NK cells. The role of IL-12 in the response to MAC infection was investigated. Depletion of endogenous IL-12 by injection of monoclonal antibody prior to and during intranasal infection with MAC resulted in an 150- to 550-fold increase in bacterial load in lung, spleen, and liver homogenates by 10 weeks postinfection. Depletion of IL-12 abrogated the ability of spleen cell cultures to produce IFN-gamma in response to stimulus with live MAC. IL-12-depleted mice showed a 75% decrease in the number of inflammatory cells entering the lungs following intranasal infection with MAC, with significant reductions in cytotoxic activity and nitric oxide production by lung cells. This work suggests that IL-12 plays a major role in the activation of IFN-gamma-producing cells during MAC infection.
Molecular and Cellular …, Jan 1, 2001
Real-time PCR-based assays specific for Brucella abortus, Brucella melitensis and Brucella suis w... more Real-time PCR-based assays specific for Brucella abortus, Brucella melitensis and Brucella suis were developed. The assays utilize an upstream primer that is derived from 3' end of the genetic element IS 711, whereas the downstream primers and probes are designed from signature sequences specific to a species or a biovar. The PCR reactions were monitored for fluorescence resonance energy transfer by including two adjacent labeled probes that hybridize to the amplicons as they are formed. The upstream probes were labeled with fluorescein at 3' end while Cy5 was attached to the 5' end of the downstream probes. An increase in the ratio of fluorescein to Cy5 fluorescence during the cycling was indicative of positive amplification event. The assays were accomplished in less than 30 min using a LightCycler in real-time mode. The assays were tested on known strains as well as field isolates and were found to be specific for all known biovars of B. abortus, B. melitensis and biovar 1 of B. suis. Therefore, specificity, sensitivity, speed and real-time detection make these assays attractive for use in epidemiological and ecological studies.
Infection and immunity, Jan 1, 1979
The bactericidal activity of guinea pig and human polymorphonuclear leukocytes (PMNs) against a s... more The bactericidal activity of guinea pig and human polymorphonuclear leukocytes (PMNs) against a smooth-intermediate strain (45/0) and a rough strain (45/20) of Brucella abortus has been examined. After incubation for 120 min, guinea pig PMNs incubated with either the smooth strain 45/0 or the rough strain 45/20 exhibited no bactericidal activity against the former and caused only a 34% decrease in viability of the latter. Human PMNs were more bactericidal than guinea pig PMNs to both strains; however, the killing of strain 45/20 by human PMNs was less than that observed in control experiments with S. aureus strain 502A. Both strains of B. abortus readily associated with guinea pig and human PMNs, and the bacteria were apparently ingested without stimulation of the hexose monophosphate pathway. Lysates (10 pg/ml, pH 5.5), prepared from guinea pig or human granules, were not particularly toxic to either strain unless supplemented with H202 and a halide (I-or Cl-). An oxygen-dependent killing system appeared to be lethal against both strains of B. abortus, with I-being more active than Cl-in the presence of H202 and granule lysate. The data suggest that degranulation after ingestion of Brucella by phagocytes does not occur due to the lack of a proper stimulus or possibly the baccilli actively inhibit the degranulation process thereby protecting the microbe from killing systems normally effective against extracellular parasites.
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Papers by Alejandro Cisneros