Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The objective of this study was to identify disease-related changes in lymphocyte populations within ileal mucosae of calves with cryptosporidiosis. Groups of five neonatal calves were orally infected at 3 days of age with 10(8) oocysts and maintained in enteric-pathogen-free conditions until clinical disease was established or until the animals had recovered from disease. Age-matched uninfected calves were used for comparison. Ileal mucosal lymphocytes were collected, quantitated, and phenotyped to determine whether changes in lymphocyte composition occurred in infected animals. We observed significantly larger numbers of intraepithelial CD8+ T lymphocytes in ileal mucosae from acutely infected calves compared with those from control animals. In addition, a proportion of intraepithelial CD4+ T cells from acutely infected calves coexpressed CD25, whereas there was an absence of coexpressed CD25 on CD4+ T cells from control calves. Ex vivo reverse transcriptase PCR of RNA from intraepithelial lymphocytes from control calves showed a cytokine expression pattern consisting of tumor necrosis factor alpha (TNF-alpha) and gamma interferon (IFN-gamma), while intraepithelial lymphocytes from calves with cryptosporidiosis expressed IFN-gamma but not TNF-alpha. Together, the results indicate that changes occur in the ileal intraepithelial lymphocyte population coincidently with Cryptosporidium parvum-induced enteric disease.
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PMID:Activation of intestinal intraepithelial T lymphocytes in calves infected with Cryptosporidium parvum. 897 10

This study was conducted to produce a recombinant species-specific oocyst wall protein of Cryptosporidium parvum. Antigens unique to C. parvum were identified by gradient sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting of oocyst proteins from several different Cryptosporidium species. Antiserum was then prepared against a 41-kDa antigen unique to C. parvum and used to identify a recombinant DNA clone, designated rCP41. Expression of CP41 mRNA in C. parvum oocysts was confirmed by reverse transcriptase PCR (RT-PCR). Although the CP41 sequence was shown by PCR to be present in the genome of C. baileyi, CP41 mRNA was not detected in this species by RT-PCR. Immunofluorescence staining with antiserum against recombinant CP41 detected native CP41 antigen on the surface of C. parvum oocysts but failed to detect CP41 on C. baileyi oocysts. Immunoelectron microscopy demonstrated that native CP41 was distributed unevenly on the C. parvum oocyst surface and was associated with amorphous oocyst wall material. In an enzyme-linked immunosorbent assay, purified rCP41 performed as well as native C. parvum oocyst protein in measuring the serological responses of young calves and adult cows to experimental and natural C. parvum infections. These results indicate that recombinant CP41 antigen may have potential in the immunodiagnosis of cryptosporidiosis.
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PMID:Cloning and expression of a DNA sequence encoding a 41-kilodalton Cryptosporidium parvum oocyst wall protein. 1054 85

Information about protease inhibitors and other antiretroviral drugs used to treat AIDS-related opportunistic infections is provided. Specific drugs addressed include ritonavir, a protease inhibitor that received the fastest approval in history, for HIV infection; Vitrasert, an intraocular form of ganciclovir, for treating CMV retinitis; 3TC, an antiviral agent for treating HIV infection; a combination of saquinavir and ritonavir for treating HIV infection; nevirapine, a reverse transcriptase inhibitor for HIV infection; nitazoxanide, available through an FDA-approved expanded access program, for cryptosporidiosis; indinavir, an HIV protease inhibitor used for HIV infection; and a combination of ddC and AZT for HIV infection.
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PMID:[New treatments for HIV]. 1136 30

The objective of this study was to determine whether changes in the ileal intraepithelial lymphocyte (TEL) phenotype and function occurred prior to development of diarrhea in Cryptosporidium parvum-infected calves. Calves were orally inoculated with 10(8) oocysts and maintained in enteric pathogen-free conditions until their use in experiments. Age-matched uninfected calves were used for comparisons. Ileal IELs were isolated and phenotyped to determine whether changes in lymphocyte population dynamics had occurred by 3 days postinoculation (PI). Ex vivo reverse transcriptase-polymerase chain reaction of messenger ribonucleic acid (mRNA) from IELs from infected calves was compared with controls to determine whether changes in cytokine expression had occurred by 3 days PI. No significant changes in lymphocyte population dynamics were documented, however, IELs isolated from 4 out of 8 infected calves, but not from 8 out of 8 control calves, expressed mRNA for interleukin-10 (IL-10). IL-10 expression by IELs was associated with the expression of a significantly larger (P < 0.001) proportion (0.75) of monoclonal antibody-defined C. parvum epitopes within infected ileal epithelium, as compared with a much smaller proportion (0.30) of epitopes with IL-10 lymphocytes. The results suggest that a temporal association exists between the expression of IL-10 by ileal IELs and the expression of C. parvum antigens in infected calf epithelium prior to development of cryptosporidiosis.
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PMID:Association of IL-10 expression by mucosal lymphocytes with increased expression of Cryptosporidium parvum epitopes in infected epithelium. 1205 98

A 173-bp fragment of the small extra-chromosomal double-stranded RNA (dsRNA) element of Cryptosporidium parvum was generated by reverse transcriptase PCR from nucleic acid extracted from whole faeces of 18 epidemiologically unrelated cases of cryptosporidiosis. Eleven different sequences were detected and two selected as reference DNA in a heteroduplex mobility assay (HMA). Although sequence diversity was detected, this was difficult to characterise because of the similarity in electrophoretic mobility of the homo- and heteroduplex bands. A PCR method was devised to generate synthetic polynucleotides of greater sequence diversity for use in the HMA. The presence of the synthetic 173-bp fragments was enriched by using, as template for the PCR, material excised from the area of the heteroduplex bands in stained electrophoresis gels. Nine novel sequences were generated and evaluated as reference sequences in the HMA. One of these with 20 bp different from the original sequence was selected for use in the HMA for improved resolution of heteroduplex and homoduplex bands and number of patterns easily resolved (nine different patterns corresponding to different DNA sequences). This method may be useful for analysis of DNA where there is limited natural variation or little sequence variation is described.
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PMID:A rapid method for identifying diversity within PCR amplicons using a heteroduplex mobility assay and synthetic polynucleotides: application to characterisation of dsRNA elements associated with Cryptosporidium. 1273 26

Differences in the virulence and fecundity of Cryptosporidium parvum isolates have been observed by several researchers studying cryptosporidiosis. The purpose of the present study was to determine if there was a correlation between intracellular levels of the viral symbiont CPV in C. parvum and fecundity of two isolates of the parasite, namely C. parvum Beltsville (B) and C. parvum Iowa (I). Dairy calves infected with 10(6)C. parvum-B excreted 5-fold more oocysts compared with calves infected with the same number of C. parvum-I oocysts. The increased fecundity of the former strain was corroborated by semi-quantitative PCR assay of DNA isolated from cell cultures infected with either C. parvum-B or C. parvum-I. Quantitative reverse transcriptase-PCR analysis of viral RNA revealed a 3-fold greater number of CPV in C. parvum-B compared with C. parvum-I oocysts. These findings may indicate a role for CPV in fecundity and possibly virulence of C. parvum.
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PMID:Fecundity of Cryptosporidium parvum is correlated with intracellular levels of the viral symbiont CPV. 1809 64

Cryptosporidium parvum is a leading pathogen in children in developing countries. To investigate whether early postnatal malnutrition leads to heavier C. parvum infections, we assessed intestinal adaptation and parasite load in suckling mice during the first 2 wk of life, analogous to the first postnatal yr in humans. Undernutrition was induced by daily C57BL6J pup separation from lactating dams. Half of the pups were separated daily, for 4 hr on day 4, 8 hr on day 5, and for 12 hr from day 6 until day 14. On day 6, each pup received an oral inoculum of 10(5) to 10(7) parasites in 10-25 microl of PBS. Littermate controls received PBS alone. Stools were assessed from days 8, 11, and 14 for oocyst counts. Mice were killed on day 14, 8 days postinoculation, at the peak of the infection. Ileal and colon segments were obtained for histology, real-time and reverse transcriptase PCR, and immunoassays. Villus and crypt lengths and cross-sectional areas were also measured. Undernourished and nourished mice infected with excysted 10(6) or 10(7) oocysts exhibited the poorest growth outcomes compared with their uninfected controls. Nourished 10(6)-infected mice had comparable weight decrements to uninfected undernourished mice. Body weight and villi were additively affected by malnutrition and cryptosporidiosis. Hyperplastic crypts and heavier inflammatory responses were found in the ilea of infected malnourished mice. Undernourished infected mice exhibited greater oocyst shedding, TNF-alpha and IFN-gamma intestinal levels, and mRNA expression compared to nourished mice infected with either 10(5) or 10(6) oocysts. Taken together, these findings show that Cryptosporidium infection can cause undernutrition and, conversely, that weanling undernutrition intensifies infection and mucosal damage.
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PMID:Cryptosporidium infection causes undernutrition and, conversely, weanling undernutrition intensifies infection. 1857 67

Cryptosporidium parvum is a widely distributed coccidian parasite and causes enteric disease in humans and animals. In addition to being a cause of life-threatening disease in immunodeficient people, mostly AIDS patients, C. parvum has been reported as a common serious primary cause of outbreaks of diarrhea in newborn calves, especially newborn ruminants (De Graaf et al. in Int J Parasitol 29:1269-1287, 1999). To obtain the recombinant P23 protein, we isolated the mRNA from oocyst of C. parvum and amplified the cDNA of P23 gene by reverse transcriptase PCR. Sequencing of cDNA showed 100% homology to the known P23 sequences. The double strand P23-cDNA was then cloned in pGEX-5X-2 expression vector. Western blot analysis of recombinant P23 showed that it could be recognized by the positive C. parvum serum. Since P23 is an immunodominant surface glycoprotein expressed in the early phase of infection (Jakobi and Petry in Microbes Infect 8:2186-2194, 2006) and the immunogenic epitopes are also found in the residual chain of amino acid sequence of this glycoprotein, the recombinant P23 was used for the screening of 437 serum samples collected from calves (#264) and cattle (#173). The dot blot analysis showed that from 264 calf and 173 cattle sera, 33% and 37% sera were positive, respectively. Due to the simple handling and equipment, dot blot analysis with P23 could be recommended for calves screening against cryptosporidiosis.
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PMID:Recombinant Cryptosporidium parvum p23 as a target for the detection of Cryptosporidium-specific antibody in calf sera. 1867 24

Pancreatitis is a well-described complication of human immunodeficiency virus (HIV) itself and its combination antiretroviral therapy. Historically, this has been predominantly associated with the usage of nucleoside reverse transcriptase inhibitors such as didanosine and stavudine, but only rarely with the usage of protease inhibitors via the induction of hypertriglyceridemia. Pancreatitis rates in HIV/AIDS population may have been exceedingly high because of the comorbid conditions prevalent in HIV/AIDS patients (e.g. ethanol use and biliary disease), and the use of non-combination antiretroviral therapy medications such as pentamidine, corticosteroids, ketoconazole, sulphonamides, metronidazole, isoniazid and opportunistic infections (e.g. cytomegalovirus, cryptosporidiosis, mycobacterial disease). In resource limited settings, where didanosine and stavudine are widely available in cheaper generic fixed dose combinations it is likely that their usage will remain in the first line HIV treatment in common. In such settings management or estimation of a patient's risk of pancreatitis still remains an issue of concern.
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PMID:Acute pancreatitis in HIV/AIDS patients: an issue of concern. 2373 May 53