[Impacts of HIV-1 resistance mutations associated with nucleoside reverse transcriptase inhibitors on viral fitness].

Nucleoside reverse transcriptase inhibitors which act as a major component of highly active antiretroviral therapy regimens are widely used in treatment of Acquired Immune Deficiency Syndrome. However, the emergence of drug-resistant variants of HIV-1 severely limits the effectiveness of these drugs. Many drug resistance mutations confer a fitness cost, which can be partially overcome by compensatory mutations or other molecular mechanisms. This review focuses on the impacts of resistance mutations emerging during treatment with nucleoside reverse transcriptase inhibitors on viral fitness, and inter actions between these mutations.

Genetic characterization of Human astrovirus infection in Wuhan, People's Republic of China, 2007-2008.

Human astrovirus (HAstV) was an important cause of viral gastroenteritis in infants in Wuhan city based on our previous study. The aim of the study was to investigate the nature of HAstV infection in Wuhan, People's Republic of China, especially in adults. Stool specimens were collected from 361 children and 301 adults with diarrhea from July 2007 to June 2008 and were tested for HAstV RNA by RT-PCR. The 348-bp PCR product of positive samples was further sequenced and analyzed for multiple sequence alignment and phylogenetic tree. HAstV RNA was detected in 2.33% (7/301) adults, which was significantly lower than that in children (13.57%, 49/361). HAstV-positive patients were either older than 50 years of age or younger than 3. Genetic analysis showed that the HAstV strain in adults was the same as that in children in 2007-2008. Contrarily, HAstV strains prevalent in 2007-2008 showed genetic characteristics different from those in 2004-2005 and belonged to two new groups of HAstV-1b. Thus, our data characterized HAstV infection in Wuhan 2007-2008, suggesting that HAstV infection also played an important role in adults in Wuhan, especial in patients of >50 years, and should be included for routine diagnosis in the population with diarrheal illness.

Changes in PGRMC1, a potential progesterone receptor, in human myometrium during pregnancy and labour at term and preterm.

This study assesses the role of progesterone receptor membrane component 1 (PGRMC1) in actions of progesterone (P4) on human myometrium during pregnancy and labour. Myometrial tissues were obtained from non-pregnant patients during hysterectomy or pregnant women undergoing C-section at term and preterm, before and during labour. PGRMC1 expression in myometrial tissues and in a human myometrial cell line (HM9) was assessed by western blots and RT-PCR. The subcellular localization of PGRMC1 in HM9 was performed by immunofluorescence staining. Isometric contractions of myometrial tissues were obtained in response to P4 with and without addition of specific antibodies against PGRMC1. Endogenous and over-expressed PGRMC1 proteins are detected by western blots in myometrial tissues, HM9 and 293 cells, respectively. PGRMC1 is localized to the plasma membrane, cytoplasm and nuclear membranes. PGRMC1 is lower in myometrium of women at term either not in labour (P = 0.004) or in labour (P = 0.005) compared with tissues from women in preterm non-labour. PGRMC1 levels are also decreased (P = 0.02) in myometrial tissues from women during preterm labour compared with preterm non-labour. P4 rapidly inhibits contractions of myometrial tissues compared with control (P < 0.05) in vitro. Pretreatment of myometrial strips with PGRMC1 antibody, suppresses the P4-induced relaxation (P < 0.05). PGRMC1 may mediate the non-genomic action of P4 and the relaxation effect on human myometrium during pregnancy. A decrease in PGRMC1 during term or preterm labour might contribute to the 'functional withdrawal' of P4 action and shift the balance to a state of heightened uterine contractility.

Prospective study of colonization and infection because of Pseudomonas aeruginosa in mechanically ventilated patients at a neonatal intensive care unit in China.

BACKGROUND: Ventilator-associated pneumonia (VAP) is an important nosocomial infection at neonatal intensive care units (NICU), frequently caused by Pseudomonas aeruginosa. A 6-month prospective study from January 2009 through June 2009 was performed to investigate the respective contribution of endogenous and exogenous transmission of P aeruginosa in the respiratory colonization or/and infection in the mechanically ventilated patients at a NICU to identify routes of lung infection with P aeruginosa and to assess risk factors for colonization or respiratory infection with P aeruginosa. METHODS: Samples from oropharyngeal swab, tracheobronchial aspirates, gastric aspirate, and rectal swab were obtained in each patient after intubation and then twice a week. Surveillance cultures for the presence of P aeruginosa from environmental surfaces of the ICU were taken once every 5 days during the study period. Pulsed-field gel electrophoresis was used to characterize the clonal relatedness of the strains by SpeI-digested genomic DNA. RESULTS: Eighteen patients (78.3%) had colonization of the upper respiratory tract. Sixteen (69.6%) patients with colonization of the respiratory tract were infected from other patients or environmental surfaces, which was considered exogenous, and, among strains causing pulmonary infection, there were 4 (50%) patients with exogenous infection. Eight of these developed VAP after a mean of 9 ± 3.4 days. The incidence of P aeruginosa VAP on the unit was 6.2%. The respiratory tract was the earliest site of colonization in all patients of VAP. Low birth weight, duration of mechanical ventilation, previous ampicillin group use, and previous second-generation cephalosporins use were independently associated with patient-related acquisition of P aeruginosa. CONCLUSION: Our results confirm that the upper respiratory tract acts as an important reservoir of P aeruginosa colonization and infection in the mechanically ventilated patients and emphasize the importance of exogenous acquisition of P aeruginosa. A combination of early identification and eradication of airways colonization by P aeruginosa plus infection control measures may be the basis to prevent pulmonary infection.

Identification of new subtype of astrovirus type 3 from an infant with diarrhea in Wuhan, China.

Human astrovirus is one of the important causes for viral gastroenteritis in young children. In previous study where we examined the molecular epidemiology of human astrovirus (HAstV) infection in infants in Wuhan City, we isolated and identified a new subtype (WH1859) of HAstV genotype 3 from an infant with diarrhea. The sequence analysis of this strain showed that the complete region of ORF2 of WH1859 contains 2385-bp of nucleotides that encode 795 amino acids. Because WH1859 strain has the identity of less than 95% with the distance of more than 0.05 to the reference strains of HAstV-3, WH1859 represents a distinct subtype within HAstV-3 strains. Further studies are needed to determine the role of this new subtype strain of HAstV in viral gastroenteritis among young children.

Study on the blood-borne virus co-infection and T lymphocyte subset among intravenous drug users.

AIM: To investigate the features of various blood-borne virus infections and co-infection in intravenous drug users (IDUs), and to examine the correlation of T lymphocyte subsets with virus co-infection. METHODS: Four hundred and six IDUs without any clinical manifestation of hepatitis and 102 healthy persons were enrolled in this study. HBV-DNA and HCV-RNA were detected by fluorescence quantitative PCR. HBsAg, HBeAg, anti-HBc, anti-HCV, HDV-Ag, anti-HGV, anti-HIV, and HCMV-IgM were assayed by enzyme-linked immunosorbent assay (ELISA) and immunochromatographic tests. The levels of Th1 and Th2 cytokines were measured by ELISA and radioactive immune assay (RIA). The T lymphocyte subpopulation was detected by using fluorescence immunoassay. The similar indices taken from the healthy persons served as controls. RESULTS: The viral infection rate among IDUs was 36.45% for HBV, 69.7% for HCV, 47.3% for HIV, 2.22% for HDV, 1.97% for HGV, and 3.45% for HCMV. The co-infection rate of blood-borne virus was detected in 255 of 406 (62.81%) IDUs. More than 80% (161/192) of subjects infected with HIV were co-infected with the other viruses, such as HBV, HCV. In contrast, among the controls, the infection rate was 17.65% for HBV and 0% for the other viruses. Our investigation showed that there was a profound decrease in the proportion of CD4/CD8 and the percentage of CD3 and CD4, but not in the percentage of CD8. The levels of PHA-induced cytokines (IFN-gamma and IL-4) and serum IL-2 were obviously decreased in IDUs. On the other hand, the level of serum IL-4 was increased. The level of IFN-gamma and the percentage of CD4 were continuously decreased when the IDUs were infected with HIV or HIV co-infection. IDUs with HIV and HBV co-infection was 15.1% (29/192). Of those 29 IDU with HIV and HBV co-infection, 51.72% (15/29) and 37.93% (11/29) were HBV-DNA-positive and HBeAg-positive, respectively. But, among IDUs without HIV infection, only 1.68% (2/119) of cases were HBV-DNA-positive. CONCLUSION: HCV, HBV and HIV infections are common in this population of IDU, leading to a high incidence of impaired Th1 cytokine levels and CD4 lymphocyte. IDUs with HIV and HBV/HCV co-infection have lower expression of Th1 cytokine with enhancement of the Th2 response. HIV may be causing HBV replication by decreasing Th1 function.

[The roles of active efflux system overexpression and outer membrane protein OprD deficiency or loss in carbapenem resistance of Pseudomonas aeruginosa].

OBJECTIVE: To investigate the mechanisms of carbapenem resistance in Pseudomonas aeruginosa (PA). METHODS: Forty-nine strains of PA were isolated from surgical intensive care unit during a period of 3 years. The levels of outer membrane protein OprD and OprN were measured by Western blotting. RT-PCR was used to measure the transcription levels of mexA gene. The metallo-beta-lactamase genes IMP and VIM and the negative regulator gene mexR for mexAB-OprM operon were amplified. The DNA fragments were sequenced by automated ABI PRISM 3700 sequencer. RESULTS: 42 of the 49 strains were resistant to carbapenem. 23 of the 42 strains showed loss of OprD and were all resistant to imipenem, but only one strain was resistant to meropenem. 18 of the 42 strains had a decreased OprD expression, 17 of which were resistant to Imipenem, and 3 were resistant to meropenem as well. 7 strains expressed OprD, all of which were sensitive to carbapenem. 27 strains overexpressed the mexAB-OprM. The resistant rate to imipenem of the mexAB-OprM overexpression group was 86.4%, not significantly different from that of the mexAB-OprM low expression group (81.5%, chi(2) = 0.005, P = 0.943). But the resistant rate to meropenem of the mexAB-OprM overexpression group was 44.4%, statistically higher than that of mexAB-OprM low expression group (13.6%, chi(2) = 5.417, P = 0.020). Nucleotide sequences and deduced amino acid sequences analysis revealed that eight strains overexpressed mexAB-OprM carried mutations in mexR gene, 7 of which had amino acid substitutions in MexR protein, and one of which had terminal code at the position of amino acid 32. 14 strains were found expressing OprN. Neither IMP gene nor VIM gene was found in the isolates. CONCLUSION: In the clinical strains from SICU, the imipenem resistance is mainly mediated by OprD deficiency or loss. Overexpression of MexAB-OprM is the primary mechanism of meropenem resistance, which is upregulated by mutations in mexR gene. Metallo-beta-lactamases IMP and VIM are rarely seen.