F. Javier Enriquez

Prevalence of Intestinal Encephalitozoonosis in Mexico

Infections with Encephalitozoon (phylum Microspora) protozoa in immunodeficient patients have emerged worldwide. The prevalence of infections due to Encephalitozoon species in nonclinical populations remains unclear. We conducted a cross-sectional survey of two rural highland villages in Mexico by using monoclonal antibody 3B6 to Encephalitozoon in immunofluorescence to assess the prevalence of Encephalitozoon spores in human stools. We found that 20 (7.84%) of the 255 subjects were positive and that 15 (21.4%) of the 70 households had at least one member who was positive. These results suggest that Encephalitozoon species, most likely Encephalitozoon intestinalis, may be commonly present in community settings.

Development of a monoclonal antibody to detect predation of the sweetpotato whitefly, Bemisia tabaci

We have developed an enzyme‐linked immunosorbent assay (ELISA) for detection of whitefly antigen in the guts of predaceous arthropods based on a monoclonal antibody (MAb) produced in response to Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) egg antigen. We observed positive antigen‐antibody reactions with the egg and the adult female stages of certain whitefly species and not with others. This MAb did not cross‐react with any of the whitefly nymphs or adult males we tested. Moreover, this MAb did not cross‐react with the various life stages of other insect species we examined. This immunologically‐based technique to identify whitefly egg facilitates examinations of predator gut contents in the field. Such a specific and sensitive whitefly egg immunoassay will expedite the characterization of the B. tabaci predator complex in the southwestern United States.

An egg-specific monoclonal antibody to Lygus hesperus

Abstract A species- and stage-specific monoclonal antibody (MAb) for a Lygus hesperus Knight egg antigen was developed. Positive antigen-antibody reactions were associated only with L. hesperus eggs and adult females. There was no cross-reactivity with any of the other L. hesperus life stages nor with any stage of L. lineolaris (Palisot de Beauvois). Furthermore, this MAb did not cross-react with the eggs of 10 other insect species examined. Electrophoretic and Western blot analyses indicated that the egg antigen had four polypeptides that bound to this MAb with molecular weights estimated at 64,000, 123,250, 140,300, and 150,300 Da. The use of this MAb as a diagnostic probe for gut content analysis of potential natural predators of L. hesperus eggs is discussed.

Adoptive Transfer of Immunity with Intraepithelial Lymphocytes in Cryptosporidium parvum-Infected Severe Combined Immunodeficient Mice

Background:Intestinal infections with the protozoan parasite Cryptosporidium parvum are prevalent in both immunocompetent and immunocompromised hosts. Although C parvum is an important cause of outbreaks and opportunistic infections worldwide, little is known about protective mucosal immune responses. This is in part because animal models of infection are limited to those with genetic or induced immunodeficiencies. Method:In this report, we isolated immune (primed) or nonimmune (unprimed) intraepithelial lymphocytes (IEL) from BALB/cJ mouse intestines, adoptively transferred them into C parvum-infected severe combined immunodeficient (SCID) mice, and evaluated infection and cell phenotype responses. Results:Control SCID mice that received no IEL shed large numbers of oocysts throughout the experimental period (day 18 to day 72). Transfer of primed IEL significantly reduced fecal oocyst shedding in recipient SCID mice compared with SCID mice that received unprimed IEL or no IEL. SCID mice transferred with unprimed IEL shed variable numbers of fecal oocysts that increased and decreased in bursts until day 57 after infection. SCID mice transferred with primed IEL exhibited significantly higher proportions of T-cell receptor (TCR) &agr;&bgr;+, CD8+, and CD8&agr;&bgr;+ EL compared with inoculated SCID mice that received unprimed or no IEL. Conclusion:We conclude that primed IEL from immunocompetent mice may influence protective mucosal response against cryptosporidiosis when transferred into SCID mice. In addition, the increased percentage of TCR &agr;&bgr;+, CD8+, CD8&agr;&bgr;+ IEL in recipient SCID mice may reflect mucosal cell populations involved in these responses during chronic C parvum infection.

Differential intra-epithelial lymphocyte phenotypes following Cryptosporidium parvum challenge in susceptible and resistant athymic strains of mice

The lack of immunocompetent laboratory animal models has limited our understanding of functional immune responses to Cryptosporidium parvum infection, but such responses have been studied in susceptible laboratory rodents with genetic, acquired, or induced immunodeficiencies. We previously observed that athymic C57BL/6J nude mice inoculated with C. parvum oocysts had lower or absent fecal oocyst excretion when compared to inoculated athymic BALB/cJ nude mice. This discrepancy prompted us to explore potential differences in intestinal immune responses in both strains. Prior to and after C. parvum challenge, BALB/cJ nude and C57BL/6J nude mice did not differ in either spleen cell numbers or in parasite-specific proliferation. However, both strains of mice exhibited a significant increase in intra-epithelial lymphocyte (IEL) numbers prior to and following C. parvum inoculation when compared to uninoculated controls (P<0.05). Prior to challenge, C57BL/6J nude mice had a higher percentage of both CD8+ and CD8+ gammadelta+ IEL than BALB/cJ nude mice. Following challenge, resistant C57BL/6J nude mice had a higher percentage of gammadelta+, CD4+, and CD8+ gammadelta+ IEL than uninoculated C57BL/6J nude mice and than susceptible BALB/cJ nude mice (P<0.05). Conversely, inoculated C57BL/6J nude mice had a significantly lower percentage of alphabeta+ IEL than inoculated BALB/cJ nude mice (P<0.05). We conclude that gammadelta+, CD4+, and/or CD8+ gammadelta+ IEL may influence responses to cryptosporidiosis in athymic murine models, and that the increased percentage of alphabeta+ IEL in susceptible BALB/cJ nude mice could reflect a preferential expression during chronic C. parvum infection and/or might downregulate local protective responses.