About 10% of the coding capacity of the Mycobacterium tuberculosis (M. tb) genome is devoted to the PE/PPE family of genes scattered throughout the genome. We have identified 28 PE/PPE operons which are organized within the M. tb genome in such a way that most PE members are upstream to PPE members. One example of such a gene arrangement is the PPE gene Rv2430c, earlier shown by us to code for a highly antigenic protein eliciting strong B-cell responses in TB patients [Choudhary, R.K., Mukhopadhyay, S., Chakhaiyar, P., Sharma, N., Murthy, K.J.R., Katoch V.M. and Hasnain, S.E. (2003) PPE antigen Rv2430c of Mycobacterium tuberculosis induces a strong B cell response. Infect. Immun. 71, 6338-6343], situated downstream to PE gene Rv2431c. Rv2431c and Rv2430c are transcribed as an operon. Expression of either rRv2431c or rRv2430c alone in E. coli limited their localization to the inclusion bodies. However, when they were co-expressed, both the proteins appeared in the soluble fraction. These two proteins interact with each other and form oligomers when alone, however, when present together they exist as heteromer.

The epidemiology of canine parvovirus (CPV) infections in dogs in India was examined using 27 isolates collected during a two-year period. The VP2 genes of 22 isolates were sequenced, and the deduced amino acid sequences were compared. The results indicated that the isolates belonged to CPV type 2a except four, which belonged to CPV type 2b. Comparison of the VP2 gene sequences revealed that the Indian isolates formed separate lineages distinct from the South East Asian isolates. The canine parvovirus isolates in India appear to evolve independently, and distinct geographical patterns of evolution could not be discerned in the isolates examined.

Although the antimicrobial activity of reactive oxygen species (ROSs) is well defined, the role of ROSs in regulating the immune response of the body is not well understood. We now provide evidence that hydrogen peroxide (H 2 O IntroductionAccumulated damage due to reactive oxygen species (ROSs) has been suggested to occur during aging 1,2 and more clearly demonstrated during the respiratory burst of phagocytes. 3,4 Hydrogen peroxide (H 2 O 2 ), is a primary component of ROSs produced in large amounts by macrophages and granulocytes and is a mediator of innate immunity against the invading pathogens. 5,6 H 2 O 2 is known to function as a second messenger 7,8 and regulates activation of many important transcription factors, such as nuclear factor-B (NF-B) and activator protein-1 (AP-1), 9,10 that control the inducible expression of genes regulating macrophage-effector functions and cytokine signaling. [11][12][13] The macrophage-induced cytokines determine the fate of the subsequent T-cell responses as type 1 14,15 or type 2. 16,17 Thus, the possibility exists that H 2 O 2 may alter the T-cell immune responses by affecting the macrophageeffector responses. The function of ROSs may not be restricted to its antimicrobial activity alone, 18 but ROSs may also play an important role in regulating the immune environment in the body. Such situations may arise during certain pathophysiologic conditions such as tuberculosis. 19,20 We earlier reported that activated macrophages from the Bruton tyrosine kinase (btk)-deficient mice (CBA/N) produced lower levels of ROSs as compared to the wild-type mice (CBA/J). 21 However, in contrast to CBA/J macrophages, the IL-12 induction was significantly higher in macrophages from CBA/N mice with T-cell responses biased toward type 1. 21,22 Although the contribution of btk enzyme in controlling the signal transduction cascades responsible for ROS production independent of IL-12 signal may not be ruled out, it is possible that btk targets the ROS pathway to influence IL-12 production. However, the exact mechanism by which ROSs down-regulate IL-12 production is not well understood. We now provide evidence that H 2 O 2 /ROSs affect the signaling events important for IL-12 production, leading to downregulation of the same in activated macrophages. Materials and methods MiceBALB/c mice were bred and maintained in the animal facility of Indian Immunologicals (IIL; Hyderabad, India). All mice were 6 to 12 weeks old and experimental protocol was approved by the Institutional Review Committee for care and usage of animals of Indian Immunologicals. Macrophage stimulation assayThe peritoneal exudate cells (PECs) were harvested by injecting 4% thioglycolate broth as described elsewhere. 23 The RAW 264.7 macrophages were obtained from NCCS (National Centre for Cell Science, Pune, India) and maintained in Dulbecco minimal essential medium (DMEM; Invitrogen, Grand Island, NY) containing 10% fetal calf serum and antibiotics (DMEM-10). The macrophages were plated at a density of 3 ϫ 10 6 cells/mL and ...

To understand the mechanism of transovarian transmission of Salmonella enteritidis in laying hens, experiments were conducted to examine the isolation of S. enteritidis from the preovulatory follicles of experimentally infected hens. Salmonella enteritidis was isolated from the preovulatory follicles in 16 birds (from follicle membrane alone in 10 birds, from the follicle yolk alone in 4 birds, and from both membrane and yolk in 2 birds). In addition, 83 S. enteritidis isolates of the major phage types prevalent in United States were tested for attachment to hen ovarian granulosa cells and HEp-2 cells. Salmonella enteritidis demonstrated three different patterns of attachment to granulosa cells, namely, local, diffuse, and aggregative; whereas, only local attachment pattern was observed on HEp-2 cells. The total number of S. enteritidis isolates that demonstrated any pattern of attachment was significantly greater on the granulosa cells than on HEp-2 cells (P < .05). Salmonella enteritidis isolates of phage Types 8 and 28 demonstrated similar patterns of attachment on granulosa cells derived from the mature and developing follicles of the hen ovary. This suggest that S. enteritidis can colonize the preovulatory follicles at different stages of development. Preincubation of bacteria with the tetrapeptide arg-gly-asp-ser, the amino acid sequence known to mediate the interaction of adhesive proteins with cells, abrogated the local attachment of bacteria to granulosa cells. These results suggest that S. enteritidis can colonize the preovulatory follicles by interacting with the ovarian granulosa cells and that adhesive proteins may be involved in this process.