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Salmonella spray promises no harm, no (infected) fowl
Gastroenterology News John H. Walsh, Section Editor
Salmonella Spray Promises No Harm, No (Infected) Fowl
cross-contamination, one Salmonellainfected bird can infect hundreds. The key, then, will be for Preempt to ood safety experts are optimistic be used on all of the flocks going to a about a new technology that enparticular slaughter plant. ables farmers to significantly reduce the Preempt would require the poulamount of Salmonella in chickens. try industry to change the way it Preempt, a spray developed by uses antibiotics. Giving antibiotics USDA scientists and MS Bioscience, to the chickens at birth, a common is a solution consisting of bacteria practice designed to protect against that occur naturally in chickens. It disease and speed the growth prowas approved by the FDA in March cess, would work against the posiand immediately hailed by Agricultive effects of the Preempt spray. ture Secretary Dan Glickman as ‘‘a Unlike irradiation, which many major milestone for food safety.’’ consumers fear despite experts’ as‘‘If this technology is used propsurances that it is safe and effective, erly, if all the flocks going into a Preempt will be welcomed by conparticular slaughter plant are being sumers, Smith de Waal predicts. treated with Preempt, it is likely to ‘‘There’s nothing exotic about it; significantly reduce the amount of it’s bacteria that currently exists in Salmonella in those products,’’ says Figure 1. Preempt (also known as CF-3) is a Caroline Smith de Waal of the Cen- bacterial spray administered to chicks that pro- the intestinal tracts of chickens, ter for Science in the Public Inter- duces normal intestinal flora and decreases infec- just being applied at an earlier est. ‘‘And if we combine it with tion with Salmonella and possibly Campylobacter in time,’’ she says. mature chickens. Still, no one expects the spray to other steps, we could have Salmobe a panacea. ‘‘I don’t think we’re nella rates, which today average 20% for chickens coming out of processbe species differences in how effec- going to see any technologies very ing plants, approaching zero.’’ tive it is, both in terms of pathogens soon that are going to mean that consumers don’t need to cook their Although Preempt has tested well and animals that it’s being used in.’’ in reducing Salmonella, it remains to Hedberg points out that because chicken,’’ Smith de Waal says. ‘‘Conbe determined whether the spray poultry slaughter and processing sumer handling will always be an will also help to protect chickens presents many opportunities for important issue.’’
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Cryptopatches: Intestinal Sites for gd T-Cell Replication p to one third of intraepithelial lymphocytes (IELs) are gd T cells, although their distribution differs in the mouse and human, with relatively more present in the mouse small intestine and in the human colon. As reviewed by Nigel Williams in the April 10, 1998 issue of Science, these cells may act as the first line of defense against intestinal infections and also may produce cytokines and growth factors that speed intestinal recovery from injury. In contrast to the more common ab T cells, which recognize antigens only after they have been broken down by enzymes into smaller fragments that are presented on antigen-presenting cells,
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against Campylobacter and other disease-causing bacteria. ‘‘It’s certainly a promising technique,’’ says Craig Hedberg, an epidemiologist with the Minnesota Health Department. ‘‘But it’s probably one in which there will
gd cells have the ability to respond to some whole proteins directly, including bacterial antigens. They also can respond to MICA and MICB, two members of the major histocompatibility complex family that are expressed on the surface of injured cells. The source of intestinal gd cells has been a mystery. Because they apparently can proliferate and differentiate outside the bone marrow in the absence of the thymus gland, an intestinal site of replication has long been suspected. In the same issue of Science, a group led by Hiromichi Ishikawa from Keio University in Tokyo reported that tiny lymphoid collections in the lamina propria, known as cryptopatches, probably are responsible for generating the intesti-
nal gd T-cell population, and perhaps also some ab IELs. Cryptopatches, which contain only about 1000 cells, are widely distributed throughout the small and large intestine. The basement membranes surrounding cryptopatches contain numerous pores through which T cells can migrate freely and thus communicate with adjacent epithelial cells. Precursor cells for gd T cells in cryptopatches have a characteristic combination of cell-surface markers They produce cKit and interleukin (IL)-7 receptors that respond to stem cell factor and IL-7, respectively. They are negative for another group of lineage markers, including CD3, commonly found in other intestinal lymphocytes. Such T-cell precursors GASTROENTEROLOGY 1998;114:1121–1122
Salmonella Spray Promises No Harm, No (Infected) Fowl
cross-contamination, one Salmonellainfected bird can infect hundreds. The key, then, will be for Preempt to ood safety experts are optimistic be used on all of the flocks going to a about a new technology that enparticular slaughter plant. ables farmers to significantly reduce the Preempt would require the poulamount of Salmonella in chickens. try industry to change the way it Preempt, a spray developed by uses antibiotics. Giving antibiotics USDA scientists and MS Bioscience, to the chickens at birth, a common is a solution consisting of bacteria practice designed to protect against that occur naturally in chickens. It disease and speed the growth prowas approved by the FDA in March cess, would work against the posiand immediately hailed by Agricultive effects of the Preempt spray. ture Secretary Dan Glickman as ‘‘a Unlike irradiation, which many major milestone for food safety.’’ consumers fear despite experts’ as‘‘If this technology is used propsurances that it is safe and effective, erly, if all the flocks going into a Preempt will be welcomed by conparticular slaughter plant are being sumers, Smith de Waal predicts. treated with Preempt, it is likely to ‘‘There’s nothing exotic about it; significantly reduce the amount of it’s bacteria that currently exists in Salmonella in those products,’’ says Figure 1. Preempt (also known as CF-3) is a Caroline Smith de Waal of the Cen- bacterial spray administered to chicks that pro- the intestinal tracts of chickens, ter for Science in the Public Inter- duces normal intestinal flora and decreases infec- just being applied at an earlier est. ‘‘And if we combine it with tion with Salmonella and possibly Campylobacter in time,’’ she says. mature chickens. Still, no one expects the spray to other steps, we could have Salmobe a panacea. ‘‘I don’t think we’re nella rates, which today average 20% for chickens coming out of processbe species differences in how effec- going to see any technologies very ing plants, approaching zero.’’ tive it is, both in terms of pathogens soon that are going to mean that consumers don’t need to cook their Although Preempt has tested well and animals that it’s being used in.’’ in reducing Salmonella, it remains to Hedberg points out that because chicken,’’ Smith de Waal says. ‘‘Conbe determined whether the spray poultry slaughter and processing sumer handling will always be an will also help to protect chickens presents many opportunities for important issue.’’
F
Cryptopatches: Intestinal Sites for gd T-Cell Replication p to one third of intraepithelial lymphocytes (IELs) are gd T cells, although their distribution differs in the mouse and human, with relatively more present in the mouse small intestine and in the human colon. As reviewed by Nigel Williams in the April 10, 1998 issue of Science, these cells may act as the first line of defense against intestinal infections and also may produce cytokines and growth factors that speed intestinal recovery from injury. In contrast to the more common ab T cells, which recognize antigens only after they have been broken down by enzymes into smaller fragments that are presented on antigen-presenting cells,
U
against Campylobacter and other disease-causing bacteria. ‘‘It’s certainly a promising technique,’’ says Craig Hedberg, an epidemiologist with the Minnesota Health Department. ‘‘But it’s probably one in which there will
gd cells have the ability to respond to some whole proteins directly, including bacterial antigens. They also can respond to MICA and MICB, two members of the major histocompatibility complex family that are expressed on the surface of injured cells. The source of intestinal gd cells has been a mystery. Because they apparently can proliferate and differentiate outside the bone marrow in the absence of the thymus gland, an intestinal site of replication has long been suspected. In the same issue of Science, a group led by Hiromichi Ishikawa from Keio University in Tokyo reported that tiny lymphoid collections in the lamina propria, known as cryptopatches, probably are responsible for generating the intesti-
nal gd T-cell population, and perhaps also some ab IELs. Cryptopatches, which contain only about 1000 cells, are widely distributed throughout the small and large intestine. The basement membranes surrounding cryptopatches contain numerous pores through which T cells can migrate freely and thus communicate with adjacent epithelial cells. Precursor cells for gd T cells in cryptopatches have a characteristic combination of cell-surface markers They produce cKit and interleukin (IL)-7 receptors that respond to stem cell factor and IL-7, respectively. They are negative for another group of lineage markers, including CD3, commonly found in other intestinal lymphocytes. Such T-cell precursors GASTROENTEROLOGY 1998;114:1121–1122