Cholera vibrios produce a single polymeric protein that (i) causes hemagglutination; (ii) appears to participate in their attachment to gut epithelium; (iii) may mediate their detachment from gut epithelium; and (iv) is a protease that hydrolyzes fibronectin and mucin, cleaves lactoferrin, and nicks the A subunit of the choleragen-related heat-labile enterotoxin of Escherchia coli.In 1947, F. M. Burnet reported the discovery of a mucinase, elaborated by Vibrio cholerae, which participated in the desquamation of epithelium from pieces of guinea pig intestine in vitro (1, 2). Even though Burnet meticulously avoided overstating his conclusions, the observations inspired a flurry of activity among cholera researchers, which led to recommendations that cholera mucinase be included in cholera vaccines (3-6). The concept that the cholera mucinase played a significant direct role in the pathogenesis of choleraic diarrhea was, however, short-lived. Gangarosa et al. (7) showed that the integrity of the intestinaltepithelium was unaltered during the disease in human beings; Gordon (8) found that the disease was not an "exudative enteropathy"; Phillips (9) observed. that the intestinal secretions were low in protein and isotonic; and Finkelstein et al. (10) found that the enterotoxin (choleragen) which caused the diarrhea of cholera could be separated from the cholera mucinase and that the mucinase was not diarrheagenic. Our current observations, however, indicate that Burnet's mucinase may still be involved in the pathogenesis of cholera even though it is not responsible directly for the diarrhea of cholera.Recent efforts in our laboratory have been directed toward understanding the mechanism(s) by which the cholera vibrios elude the host intestinal clearance mechanisms of mucus secretion and peristalsis (11). We have isolated (12), from broth cultures of V. cholerae, a hemagglutinin (HA), which we previously called cholera lectin (13). This protein, a polymer of 32,000 Mr subunits, which appears to participate in the attachment of cholera vibrios to intestinal epithelium, has inherent protease activity (12). Specific antibody against the purified HA inhibits its protease function and also inhibits attachment of V. cholerae to intestinal epithelium (12).The present report shows that the HA/lectin/protease is produced in both a cell-associated and a soluble form in vivo and that it hydrolyzes fibronectin, mucin, -and lactoferrin-three proteins that may participate in host defense against cholera. It also nicks the A subunit of the choleragen-related heat-labile enterotoxin (LT) of Escherichia coli (14) 18)]. The infant rabbits (nine were inoculated with CA 401, three with 569B, and five with 3083) were sacrificed approximately 18 hr later and intestinal fluids ranging between 6 and 17.5 ml and containing 2.0-42 x 107 live cholera vibrios per ml, were harvested and lightly centrifuged (200 x g for 5 min) to sediment the nonbacterial solids. The supernates were subjected to higher speed (12,000 x g for 20 min) cent...

A move from conventional cages to either an enriched cage or a noncage system may affect the safety or quality, or both, of the eggs laid by hens raised in this new environment. The safety of the eggs may be altered either microbiologically through contamination of internal contents with Salmonella enterica serovar Enteritidis (Salmonella Enteritidis) or other pathogens, or both, or chemically due to contamination of internal contents with dioxins, pesticides, or heavy metals. Quality may be affected through changes in the integrity of the shell, yolk, or albumen along with changes in function, composition, or nutrition. Season, hen breed, flock age, and flock disease-vaccination status also interact to affect egg safety and quality and must be taken into account. An understanding of these different effects is prudent before any large-scale move to an alternative housing system is undertaken.

Prompt refrigeration to temperatures capable of restricting microbial growth has been recommended as an approach to reducing the likelihood that contaminated eggs will transmit Salmonella enteritidis to humans. By using experimentally contaminated egg components, the present study determined the extent to which small numbers of S. enteritidis could grow to more dangerous levels at different temperatures over a period up to 3 d. This model was intended to simulate the potential opportunities for S. enteritidis multiplication following oviposition and prior to the achievement of internal temperatures able to prevent further microbial growth in eggs. At a relatively warmer incubation temperature (25 C) and with higher inoculum doses (150 cells), rapid and substantial S. enteritidis multiplication often occurred, especially when the bacteria had an opportunity for access to yolk nutrients and when contaminated eggs were incubated for 2 or 3 d before sampling. Extensive multiplication of S. enteritidis was less frequently observed at lower inoculum doses (15 cells), shorter storage times (1 d), and lower temperatures (10 to 17.5 C) and when contaminants were introduced into the albumen.

Houseflies (Musca domestica) released into rooms containing hens challenged with Salmonella enterica serovar Enteritidis (Salmonella serovar Enteritidis) rapidly became contaminated with Salmonella serovar Enteritidis. Forty to 50% of the flies were contaminated at 48 h, and the percentage increased to 50 to 70% at 4 and 7 days postexposure and then decreased to 30% at day 15. Initial attempts at recovering surface organisms for culture using an aqueous rinse were largely unsuccessful, while cultures of internal contents readily recovered Salmonella serovar Enteritidis. However, when 0.5% detergent was incorporated into the rinse, high recovery levels of bacteria were observed from both external and internal culture regimens, indicating equal distribution of the organism on and in the fly and a tighter interaction of the organism with the host than previously thought. Salmonella serovar Enteritidis was isolated routinely from the fly gut, on rare occasions from the crop, and never from the salivary gland. Feeding contaminated flies to hens resulted in gut colonization of a third of the birds, but release of contaminated flies in a room containing previously unchallenged hens failed to result in colonization of any of the subject birds. These results indicate that flies exposed to an environment containing Salmonella serovar Enteritidis can become colonized with the organism and might serve as a source for transmission of Salmonella serovar Enteritidis within a flock situation.

Induced molting is an important economic tool used by the egg industry to recycle an aging layer flock. It is estimated that approximately 70% of the flocks nationwide and almost 100% in California are molted annually. Considering that there are approximately 240 million hens in production in the U.S., a rough estimate of the numbers of hens molted every year would be between 144 and 168 million birds, a substantial number. There are many methods to induce molt, but feed removal until hens lose a specific weight is the most prevalent molt strategy in the U.S. However, experimental studies in our laboratory have shown that induced molting via feed removal depresses the immune system of hens and exacerbates a Salmonella enteritidis (SE) problem in a simulated flock situation. Molted hens excreted significantly higher SE numbers in the feces, had higher numbers of SE in internal organs, and exhibited more intestinal inflammation. Molted hens were 100- to 1,000-fold more susceptible to infection by SE and therefore more readily transmitted the organism to uninfected hens in neighboring cages. With the problems identified, solutions were sought, and several were successful in ameliorating the SE issue. Antibiotic therapy, vaccination, and use of low-energy, low-calcium diets to molt hens all dramatically decreased SE shedding during molt. All of the solutions provide the producer with many potential solutions to the SE food safety issue and still allow them to recycle their hens.