[Exploration and thinking on functional preservation after orthotopic neobladder construction].

The concept of functional preservation after orthotopic neobladder construction has gradually attracted attention. Reconstruction of urine storage and voiding is the basic function preservation of orthotopic neobladder. Clinical exploration mainly focuses on the optimization of neobladder reconstruction methods and procedures, and there is still a lack of summary of existing surgical characteristics and high-quality functional comparative studies. For strictly selected patients, on the basis of tumor control and standardized postoperative rehabilitation guidance, most patients with preserved nerve can retain satisfied sexual function after surgery. The protection of neurovascular bundle and ancillary structures combined with postoperative exercise is crucial to the improvement of urinary continence. According to the characteristics of patients, choosing the appropriate urinary diversion methods and function preserving can help patients establish a normal life style after surgery and improve their self-image and quality of life.

[Risk factors of permanent stoma in rectal cancer patients undergoing transabdominal anterior resection with temporary stoma].

Objective: To investigate the risk factors of turning temporary stoma into permanent stoma in rectal cancer patients undergoing transabdominal anterior resection with temporary stoma. Methods: A case-control study was carried out. Data of rectal cancer patients who underwent transabdominal anterior resection with temporary stoma and completed follow-up in Department of General Surgery of Xiangya Hospital of Central South University from June 2008 to June 2018 were collected and analyzed. In this study, temporary stoma included defunctioning stoma (ostomy was made during operation) and salvage stoma (ostomy was made within one month after operation due to anastomotic leakage or severe complications). Cases of multiple intestinal tumors were excluded. A total of 308 rectal cancer patients were enrolled in the study, including 198 males and 110 females with a median age of 56 (48-65) years. Ninety-four patients received intraperitoneal chemotherapy during operation. Among 308 patients, upper rectal cancer was observed in 64 cases, middle rectal cancer in 89 cases and low rectal cancer in 155 cases. Twenty patients underwent transverse colostomy and 288 underwent ileostomy. Phone call following-up was conducted from August to September 2019 to investigate whether stoma was reversed, causes of reversal failure, and tumor relapsed or not in detail. Permanent stoma was defined as that the stoma was still not reversed by the latest follow-up. The univariate analysis was performed with chi-square test or Fisher's exact test, and variables with P value < 0.10 were included in the non-conditional logistic regression model for multivariate analysis. Results: The median follow-up time was 54.3 (32.4-73.8) months. During follow-up, 8 cases had local recurrence and 37 cases had distant metastasis. Among the 308 patients with temporary ostomy, 247 (80.2%) patients had stomas reversed and the median interval time was 4.5 (3.5-6.1) months. The median interval time in 65 patients with salvage stoma was significantly longer that in 182 patients with defunctioning stoma [5.5 (4.3-7.5) vs. 4.2 (3.4-5.5) months; Z=-4.387, P<0.001]. The temporary ostomy was confirmed to become permanent stoma in 61 patients (19.8%), including 45 cases of defunctioning stoma and 16 cases of salvage stoma. Univariate analysis showed that preoperative anemia, intraperitoneal chemotherapy during operation, middle rectal cancer, transverse colostomy, pathological stage, postoperative local recurrence and distant metastasis were associated with permanent stoma (all P<0.10). Multivariate analysis revealed that the intraperitoneal chemotherapy during operation (OR=1.961, 95% CI: 1.029-3.738, P=0.041), middle rectal cancer (OR=2.401, 95% CI: 1.195-4.826, P=0.014), transverse colostomy (OR=3.433, 95% CI: 1.234-9.553, P=0.018), and distant metastasis (OR=8.282, 95% CI:3.820-17.954, P<0.001) were independent risk factors of permanent stoma. Conclusions: There is high risk of turning temporary stoma into permanent stoma among rectal cancer patients undergoing transabdominal anterior resection who receive intraperitoneal chemotherapy during operation, present as the middle rectal cancer, undergo transverse colostomy or develop distant metastasis. Surgeons need to evaluate and balance the risks and benefits thoroughly, and then inform the patients in order to avoid potential conflicts.

Clinical significance of tumor mutation burden and DNA damage repair in advanced stage non-small cell lung cancer patients.

OBJECTIVE: This study aimed to investigate the impact of tumor mutational burden (TMB) and DNA damage repair (DDR) gene alteration on overall survival (OS) in advanced non-small cell lung cancer (NSCLC) patients. PATIENTS AND METHODS: A DNA library of cancer cells from 67 NSCLC patients in stages III-IV was constructed for next-generation sequencing (NGS). Geneseeq422 probes were used for hybridization enrichment. The target-enriched library was sequenced on HiSeqNGS platforms, and we analyzed the relevant signaling pathways. Then, we correlated the OS of the patients with TMB and DDR mutations. RESULTS: Many significant alterations were found, including in the EGFR, p53, KRAS, RB1, ERBB2, NF1, DNMT3A, ALK, MYC, PIK3CA, ROS1, BRAF, ARID1A, PTEN, CDKN2A, and FGF19 genes. We also identified many mutations in the genes relevant to the DDR pathway. Interestingly, we found that the TMB of patients with DDR gene mutations was dramatically higher than that in the DDR wild-type (WT). Univariable analysis showed that DNMT3A, RB1, DDR pathway-related gene mutations, and TMB were critical factors for the effects on OS. Multivariable analysis confirmed that DNMT3A and mutations in the DDR pathway-related genes were important for predicting OS. CONCLUSIONS: Multiple mutations in the genes of the DDR pathway caused higher TMB levels, which resulted in longer OS. By contrast, OS was significantly longer in patients with non-DNMT3A mutations than in those with DNMT3A variants. DNMT3A alteration in NSCLC patients led to poor outcomes.

[Interpretation of clinical practice guideline for anorectal day surgery 2019 edition].

As the rapid development of minimally invasive techniques, anesthesia, and enhanced recovery after surgery (ERAS), anorectal day surgery receiving more and more attention by improving efficiency of medical care while reducing cost and hospitalized infection. However, day surgery also faces the challenge of completing the whole process from patient admission to discharge within 24 hours. Therefore, establishing a reasonable and detailed day surgery process is the cornerstone to guarantee safe medical practice and patients satisfaction. National Clinical Research Center for Geriatric Disorders (Xiangya), together with China Ambulatory Surgery Alliance formulates the clinical practice guideline for anorectal day surgery 2019 edition. Here we make some interpretations of the guidelines on the detailed process of anorectal day surgery, including indication, preoperative examination, preoperative risk evaluation, health education, assessment of day surgery anesthesia and before leaving postanesthesia care unit (PACU), postoperative management, assessment of discharge and follow-up, for the convenience of various medical centers.

δ34S and δ18O of dissolved sulfate as biotic tracer of biogeochemical influences on arsenic mobilization in groundwater in the Hetao Plain, Inner Mongolia, China.

Environmental isotopology of sulfur and oxygen of dissolved sulfate in groundwater was conducted in the Hetao Plain, northwestern China, aiming to better understand the processes controlling arsenic mobilization in arsenic-rich aqueous systems. A total of 22 groundwater samples were collected from domestic wells in the Hetao Plain. Arsenic concentrations ranged from 11.0 to 388 µg/L. The δ(34)S-SO4 and δ(18)O-SO4 values of dissolved sulfate covered a range from +1.48 to +22.4‰ and +8.17‰ to +14.8‰ in groundwater, respectively. The wide range of δ(34)S-SO4 values reflected either an input of different sources of sulfate, such as gypsum dissolution and fertilizer application, or a modification from biogeochemical process of bacterial sulfate reduction. The positive correlation between δ(34)S-SO4 and arsenic concentrations suggested that bacteria mediated processes played an important role in the mobilization of arsenic. The δ(18)O-SO4 values correlated non-linearly with δ(34)S-SO4, but within a relatively narrow range (+8.17 to +14.8‰), implying that complexities inherent in the sulfate-oxygen (O-SO4(2-)) origins, for instance, water-derived oxygen (O-H2O), molecular oxygen (O-O2) and isotope exchanging with dissolved oxides, are accounted for oxygen isotope composition of dissolved sulfate in groundwater in the Hetao Plain.

Proficiency of drug susceptibility testing for Mycobacterium tuberculosis in Taiwan, 2007-2011.

SETTING: Authorised clinical mycobacteriology laboratories in Taiwan. OBJECTIVE: To evaluate the impact of external quality assessment (EQA) on the quality of drug susceptibility testing (DST) in 2007-2011. DESIGN: Panels consisting of 20-30 Mycobacterium tuberculosis strains were used. Efficiency of 95% in detecting resistance to both isoniazid (INH) and rifampicin (RMP), and of 90% to ethambutol (EMB) and streptomycin (SM) was used to define a competent laboratory. RESULTS: The proportion of laboratories that fulfilled the competency criteria for all first-line drugs was 16.7% in 2007, increasing to 85.7% in 2008, 86.1% in 2009, 82.4% in 2010, and to 96.8% in 2011 (P < 0.01). The mean efficiency in detecting resistance to INH and RMP reached >99% during 2008-2011 (P = 0.90 for INH and P = 0.82 for RMP), and for EMB it increased from 82.0% in 2007 to 92.2% in 2008 and 99.5% in 2011 (P < 0.01), while that for resistance to SM increased from 82.0% in 2007 to 98.1% in 2008 and 99.5% in 2011 (P < 0.01). Preparations of inoculum for DST and detection of EMB resistance were the main reasons for non-competence. CONCLUSION: The EQA programme was effective in improving the competency of clinical laboratories in performing DST for tuberculosis.

Characteristics of a widespread community cluster of H275Y oseltamivir-resistant A(H1N1)pdm09 influenza in Australia.

BACKGROUND: Oseltamivir resistance in A(H1N1)pdm09 influenza is rare, particularly in untreated community cases. Sustained community transmission has not previously been reported. METHODS: Influenza specimens from the Asia-Pacific region were collected through sentinel surveillance, hospital, and general practitioner networks. Clinical and epidemiological information was collected on patients infected with oseltamivir-resistant viruses. RESULTS: Twenty-nine (15%) of 191 A(H1N1)pdm09 viruses collected between May and September 2011 from Hunter New England (HNE), Australia, contained the H275Y neuraminidase substitution responsible for oseltamivir resistance. Only 1 patient had received oseltamivir before specimen collection. The resistant strains were genetically very closely related, suggesting the spread of a single variant. Ninety percent of cases lived within 50 kilometers. Three genetically similar oseltamivir-resistant variants were detected outside of HNE, including 1 strain from Perth, approximately 4000 kilometers away. Computational analysis predicted that neuraminidase substitutions V241I, N369K, and N386S in these viruses may offset the destabilizing effect of the H275Y substitution. CONCLUSIONS: This cluster represents the first widespread community transmission of H275Y oseltamivir-resistant A(H1N1)pdm09 influenza. These cases and data on potential permissive mutations suggest that currently circulating A(H1N1)pdm09 viruses retain viral fitness in the presence of the H275Y mutation and that widespread emergence of oseltamivir-resistant strains may now be more likely.

Validation of the Chinese version of the Halitosis Associated Life-quality Test (HALT) questionnaire.

OBJECTIVE: This study aimed to evaluate the reliability and validity of the Chinese version of the Halitosis Associated Life-quality Test (HALT) questionnaire. METHODS: A total of 106 patients with oral malodour were recruited to complete the questionnaire after its translation and cross-cultural adaptation. The reliability of the Chinese version of the HALT was evaluated using internal consistency and test-retest methods. Both construct validity and discriminative validity were adopted to evaluate the validity of the HALT. RESULTS: The Cronbach's alpha value (internal reliability) for the total HALT score was 0.95, and the intraclass correlation coefficient (ICC) value (test-retest reliability) was 0.89 (95% CI = 0.74-0.98). The construct validity was determined by exploratory factor analysis. Four factors were extracted, which accounted for 85.18% of the variance. All items had factor loadings above 0.40, ranging from 0.53 to 0.94. In addition, the Chinese version of the HALT was found to be valid for distinguishing patients with different degrees of oral malodour. CONCLUSION: The results suggest that the Chinese version of the HALT has satisfactory psychometric properties and is applicable to patients with oral malodour in Chinese-speaking populations.

Increased detection in Australia and Singapore of a novel influenza A(H1N1)2009 variant with reduced oseltamivir and zanamivir sensitivity due to a S247N neuraminidase mutation.

A novel influenza A(H1N1)2009 variant with mildly reduced oseltamivir and zanamivir sensitivity has been detected in more than 10% of community specimens in Singapore and more than 30% of samples from northern Australia during the early months of 2011. The variant, which has also been detected in other regions of the Asia-Pacific, contains a S247N neuraminidase mutation. When combined with the H275Y mutation, as detected in an oseltamivir-treated patient, the dual S247N+H275Y mutant had extremely high oseltamivir resistance.

Environmental geochemistry of abandoned flotation tailing reservior from the Tonglvshan Fe-Cu sulfide mine in Daye, Central China.

This study investigated metals of tailings from Tonglvshan mine in Daye and assessed the effect of metal contamination in water and sediment near the tailing reservoir. The concentration of copper, lead, zinc, cadmium, chromium and nickel was measured in deposit samples taken from a profile in an abandoned flotation tailing reservoir, as well as in water and sediment samples near the reservoir. The results of this study indicate that copper concentration ranges from 780 to 4390 mg/kg, 2-10 times higher than the limit values in soil, while the contents of other metals are below the limit values. Metal levels in water and sediments are high and varied widely in different sampling sites. The mean concentrations of copper, lead, zinc, cadmium, chromium and nickel in waters are 27.76, 2.28, 8.20, 0.12, 5.30 and 3.04 mg/L, while those in sediments are 557.65, 96.95, 285.20, 0.92, 94.30 and 4.75 mg/kg, respectively. All of the results indicate that the environment near the tailing reservoir is polluted to some extent by some kinds of metals, especially by copper, lead, zinc and cadmium, which may be caused not only by some discharge sources of metals, but also by life garbage and sewage.

Oseltamivir-resistant influenza viruses circulating during the first year of the influenza A(H1N1) 2009 pandemic in the Asia-Pacific region, March 2009 to March 2010.

During the first year of the influenza A(H1N1) 2009 pandemic, unprecedented amounts of the neuraminidase inhibitors, predominantly oseltamivir, were used in economically developed countries for the treatment and prophylaxis of patients prior to the availability of a pandemic vaccine. Due to concerns about the development of resistance, over 1,400 influenza A(H1N1) 2009 viruses isolated from the Asia-Pacific region during the first year of the pandemic (March 2009 to March 2010) were analysed by phenotypic and genotypic assays to determine their susceptibility to the neuraminidase inhibitors. Amongst viruses submitted to the World Health Organization Collaborating Centre for Reference and Research in Melbourne, Australia,oseltamivir resistance was detected in 1.3% of influenza A(H1N1) 2009 strains from Australia and 3.1% of strains from Singapore, but none was detected in specimens received from other countries in Oceania or south-east Asia, or in east Asia. The overall frequency of oseltamivir resistance in the Asia-Pacific region was 16 of 1,488 (1.1%). No zanamivir-resistant viruses were detected. Of the 16 oseltamivir-resistant isolates detected, nine were from immunocompromised individuals undergoing oseltamivir treatment and three were from immunocompetent individuals undergoing oseltamivir treatment. Importantly, four oseltamivir-resistant strains were from immunocompetent individuals who had not been treated with oseltamivir, demonstrating limited low-level community transmission of oseltamivir-resistant strains. Even with increased use of oseltamivir during the pandemic, the frequency of resistance has been low, with little evidence of community-wide spread of the resistant strains. Nevertheless, prudent use of the neuraminidase inhibitors remains necessary, as does continued monitoring for drug-resistant influenza viruses.

Downregulation of microRNA-383 is associated with male infertility and promotes testicular embryonal carcinoma cell proliferation by targeting IRF1.

Our previous studies have shown that microRNA-383 (miR-383) expression is downregulated in the testes of infertile men with maturation arrest (MA). However, the underlying mechanisms of miR-383 involved in the pathogenesis of MA remain unknown. In this study, we showed that downregulation of miR-383 was associated with hyperactive proliferation of germ cells in patients with mixed patterns of MA. Overexpression of miR-383 in NT2 (testicular embryonal carcinoma) cells resulted in suppression of proliferation, G1-phase arrest and induction of apoptosis, whereas silencing of miR-383 reversed these effects. The effects of miR-383 were mediated through targeting a tumor suppressor, interferon regulatory factor-1 (IRF1), and miR-383 was negatively correlated with IRF1 protein expression in vivo. miR-383 inhibited IRF1 by affecting its mRNA stability, which subsequently reduced the levels of the targets of IRF1, namely cyclin D1, CDK2 and p21. Downregulation of IRF1 or cyclin D1, but not that of CDK2, enhanced miR-383-mediated effects, whereas silencing of p21 partially inhibited the effects of miR-383. Moreover, miR-383 downregulated CDK4 by increasing proteasome-dependent degradation of CDK4, which in turn resulted in an inhibition of phosphorylated retinoblastoma protein (pRb) phosphorylation. These results suggest that miR-383 functions as a negative regulator of proliferation by targeting IRF1, in part, through inactivation of the pRb pathway. Abnormal testicular miR-383 expression may potentiate the connections between male infertility and testicular germ cell tumor.

Adamantane resistance in influenza A(H1) viruses increased in 2007 in South East Asia but decreased in Australia and some other countries.

The adamantanes (amantadine and rimantadine) were the initial antivirals licensed for use against influenza A viruses and have been used in some countries to control seasonal influenza and have also been stockpiled for potential pandemic use. While high rates of resistance have been observed in recent years with A(H3) viruses, the rates of resistance with A(H1) viruses has varied widely. In this study we analysed 281 human influenza A viruses isolated in 2007 that were referred to the WHO Collaborating Centre for Reference and Research in Melbourne, mainly from Australia and the surrounding regions, for evidence of resistance to adamantanes and a subset of these was examined for resistance to the neuraminidase inhibitors (NIs). We found that the rates of adamantane resistance in A(H3) viruses continued to increase in most countries in 2007 but a distinct variation was seen with A(H1) resistance levels. A(H1) viruses from Australia, New Zealand and Europe had low rates of resistance (2-9%) whereas viruses from a number of South East (SE) Asian countries had high rates of resistance (33-100%). This difference can be attributed to the spread of A/Brisbane/59/2007-like viruses to many parts of the world with the exception of SE Asia where A/Hong Kong/2652/2006-like viruses continue to predominate. When these two A(H1) subgroups were compared for their in vitro sensitivity to the other class of influenza antiviral drugs, the neuraminidase inhibitors, no difference was seen between the groups with both showing normal levels of sensitivity to these drugs, The finding of reducing A(H1) resistance rates in Australia and rising levels in SE Asia in 2007, reverses the trend seen in 2006 when A(H1) resistance levels were rising in Australia and elsewhere but remained low in most of SE Asia.

Development of food-grade cloning and expression vectors for Lactococcus lactis.

AIMS: To develop food-grade cloning and expression vectors for use in genetic modification of Lactococcus lactis. METHODS AND RESULTS: Two plasmid replicons and three dominant selection markers were isolated from L. lactis and used to construct five food-grade cloning vectors. These vectors were composed of DNA only from L. lactis and contained no antibiotic resistance markers. Three of the vectors (pND632, pND648 and pND969) were based on the same plasmid replicon and carried, either alone or in combination, the three different selectable markers encoding resistance to nisin, cadmium and/or copper. The other two (pND965DJ and pND965RS) were derived from a cadmium resistance plasmid, and carried a constitutive promoter and a copper-inducible promoter, respectively, immediately upstream of a multicloning site. All vectors were stable in L. lactis LM0230 for at least 40 generations without selection pressure. The two groups of vectors were compatible in L. lactis LM0230. The vectors pND648 and pND965RS, as representatives of the two groups, were transferred successfully by electroporation into and maintained in an industrial strain of L. lactis. The usefulness of the vectors was further demonstrated by expressing a phage resistance gene (abiI) in another industrial strain of L. lactis. CONCLUSIONS: The five food-grade vectors constructed are potentially useful for industrial strains of L. lactis. SIGNIFICANCE AND IMPACT OF THE STUDY: These vectors represent a new set of molecular tools useful for food-grade modifications of L. lactis.

Chemo- and radio-protective effects of polysaccharide of Spirulina platensis on hemopoietic system of mice and dogs.

AIM: To observe polysaccharide of Spirulina platensis (PSp) on the hematopoietic system of mouse and dogs which were damaged by injection of cyclophosphamide (CTX) and 60Co-gamma irradiation. METHODS: CTX and 60Co gamma ray were used to induce bone marrow damage, and the experimental animals were ig with different dose of PSp in vivo, after 12-d and 21-d administration, the whole blood cells and nucleated cells in bone marrow were measured, and the DNA in bone marrow were inspected by UV-spectrophotometer. RESULTS: CTX and 60Co-gamma irradiation induced hemopoietic system damage in mice and dogs, respectively. PSp 30, 60 mg/kg increased the level of the white cells in blood and nucleated cells and DNA in bone marrow in mice but had no effects on red cells and hemoglobins. PSp 12 mg/kg increased the level of red cells, white cells, and hemoglobins in blood and nucleated cells in bone marrow in dogs (P < 0.01), and the effects of PSp 60 mg/kg were better than that of berbamine hydrochloride 60 mg/kg. CONCLUSION: PSp has chemo-protective and radio-protective capability, and may be a potential adjunct to cancer therapy.

Mapping dispersed repetitive loci using semi-specific PCR cloning and somatic cell hybrid mapping.

A simple and effective method based upon semi-specific PCR followed by cloning has been developed. Chromosomal mapping of the generated fragment on a somatic cell hybrid panel identifies the chromosomal position, and yields a unique sequence tag for the site. Using this method, the chromosomal location of one porcine endogenous retrovirus (PERV) was determined. The porcine genomic sequences were first amplified by PCR using a PERV-specific primer and a porcine short interspersed nuclear element (SINE)-specific primer. PCR products were cloned, and those sequences that contained PERV plus flanking regions were selected using a second round of PCR and cloning. Sequences flanking the PERV were determined and a PERV-B was physically mapped on porcine chromosome 17 using a somatic hybrid panel. The general utility of the method was subsequently demonstrated by locating PERVs in the genome of PERV infected human 293 cells. This method obviates the need for individual library construction or linker/adaptor ligation, and can be used to quickly locate individual sites of moderately repeated, dispersed DNA sequences in any genome.

LldI, a plasmid-encoded type I restriction and modification system in Lactococcus lactis.

A plasmid-encoded type I restriction and modification (R-M) system, designated LldI, was identified in Lactococcus lactis biovar diacetylactis LD10-1. LldI consists of three genes encoding endonuclease, methylase and specificity subunits, respectively. RT-PCR analysis revealed that the three genes are co-transcribed as a polycistronic mRNA in L. lactis. The specificity subunit of LldI differs significantly in the target recognition domains from those of other type I R-M systems, suggesting that LldI confers a novel specificity in L. lactis.

Transmission of porcine endogenous retroviruses in severe combined immunodeficient mice xenotransplanted with fetal porcine pancreatic cells.

BACKGROUND: Xenotransplantation using pig organs or tissues may alleviate the human donor organ shortage. However, one concern is the potential transmission of pig pathogens to humans, especially pig endogenous retroviruses (PERV), which infect human cell lines in vitro. In this report, the cross-species in vivo transmission of PERV by xenotransplantation was studied using a severe combined immunodeficient (SCID) mouse model. METHODS: Twenty-one SCID mice were transplanted with fetal pig pancreatic cells and left for periods from three to 41 weeks before being killed. DNA and RNA were extracted from liver, spleen, and brain of these mice, and examined for PERV using nested polymerase chain reaction (PCR) and reverse transcriptase-PCR. The pig mitochondrial cytochrome oxidase II subunit gene (COII) was also amplified to monitor the presence of pig cell microchimerism in xenotransplanted tissues, and a housekeeping gene was included to monitor the DNA quality and quantity. RESULTS: Examination of 39 DNA samples from tissues of the 21 xenografted mice identified two mouse tissues (M4-liver and M19-spleen) that were positive for PERV but negative for COII. A total of 23 (59%) of the mouse tissues were positive for both PERV and COII, 6 (16%) were negative for both, and 8 (20%) were positive for COII only. PCR and direct sequencing of the PCR products identified three PERV variants, which were different from the PERV sequence detected by PCR direct sequencing from the pig donor cells. CONCLUSIONS: The PERV+/COII- results from M4-liver and M19-spleen indicated the presence of PERV transmission from pig to mouse tissue. The PERV variants detected in the mouse tissues indicated that different PERVs were transmissible from the pig to mouse tissue during xenotransplantation. The negative reverse transcriptase-PCR results for PERV from three mouse samples including M4-liver and M19-spleen suggest there was no active PERV transcription in the mouse tissues, although this would need to be studied further.

Genetic organization and functional analysis of a novel phage abortive infection system, AbiL, from Lactococcus lactis.

A plasmid-encoded phage abortive infection mechanism (AbiL) was identified from Lactococcus lactis biovar. diacetylactis LD10-1. AbiL conferred complete resistance to the small isometric-headed phage phi 712 (936 species) and partial resistance to the prolate-headed phage phi c2 (c2 species) when introduced into L. lactis LM0230. However, AbiL was not effective against the small isometric-headed phage ul36 (P335 species). The AbiL determinant was sequenced and it consists of two open reading frames, abiLi and abiLii. Their encoded proteins did not share significant homology with any known proteins in the protein databases. Transcriptional analysis indicated that abiLi and abiLii are organized as a single operon. Deletion within abiLii abolished the phage resistance. The levels of four phi c2-specific transcripts, three within the early transcribed region and one within the late transcribed region, were examined by RT-PCR, no effect of AbiL on synthesis of these transcripts was detected, suggesting that AbiL may act at a point after the transcription of phi c2 in L. lactis.