Displaying publications 1 - 20 of 29 in total

Abstract:
Sort:
  1. Characterization of species B adenoviruses isolated from fecal specimens taken from poliomyelitis-suspected cases
    de Azevedo JP, Nascimento LR, Cortinovis MC, Oliveira SS, da Costa EV, da Silva EE
    J Clin Virol, 2004 Dec;31(4):248-52.
    PMID: 15494264 DOI: 10.1016/j.jcv.2004.04.007
    BACKGROUND: Human adenoviruses are classified into six species, A-F, and 51 serotypes are recognized. Adenoviruses can cause a broad range of diseases. Serotypes 3, 7 and 21 are most commonly associated with CNS disease. Serotype 21 (specie B) was isolated from brain tissue and CSF of patients with acute flaccid paralysis (AFP) in Malaysia.
    OBJECTIVES: Characterize, by molecular methods, species B adenoviruses isolated from poliomyelitis-suspected cases and investigate the possible etiological role of adenoviruses in acute flaccid paralysis (AFP).
    STUDY DESIGN: 622 virus isolates, including Sabin-related polioviruses, non-polio enteroviruses (NPEV) and adenoviruses, were recovered from fecal specimens in our laboratory during the period of 1997-2002 from AFP cases occurring in Brazil, Peru and Bolivia. Negative controls consisted of 528 fecal specimens collected from healthy children <==5 of age. Of these, 478 were contacts of AFP negative cases and 50 were from a day-care center.
    RESULTS: Sixty-four adenovirus strains isolated in HEp2 (human laryngeal tumor cells) cells were confirmed as such by an adenovirus-group specific PCR. Nucleotide sequencing identified the following adenovirus species: A (3 isolates), B (20 isolates), C (38 isolates), D (2 isolates) and E (1 isolate). The following serotypes belonging to the species B were identified: Ad3 (1 strain), Ad7 (17 strains) and, Ad16 (2 strains).
    CONCLUSION: Other viral agents became more recognized in association with CNS diseases in areas where wild polioviruses have been eradicated. The possible role of species B adenoviruses in the etiology of AFP cases similar to that caused by wild poliovirus is discussed.
  2. Fulltext Evaluation of the Elecsys(®) Anti-HCV II assay for routine hepatitis C virus screening of different Asian Pacific populations and detection of early infection
    Yoo SJ, Wang LL, Ning HC, Tao CM, Hirankarn N, Kuakarn S, et al.
    J Clin Virol, 2015 Mar;64:20-7.
    PMID: 25728074 DOI: 10.1016/j.jcv.2014.12.015
    Early diagnosis of hepatitis C virus (HCV) infection is essential to allow appropriate treatment and prevent transmission.
  3. Fulltext A RT-PCR assay for the detection of coronaviruses from four genera
    Xiu L, Binder RA, Alarja NA, Kochek K, Coleman KK, Than ST, et al.
    J Clin Virol, 2020 07;128:104391.
    PMID: 32403008 DOI: 10.1016/j.jcv.2020.104391
    BACKGROUND: During the past two decades, three novel coronaviruses (CoVs) have emerged to cause international human epidemics with severe morbidity. CoVs have also emerged to cause severe epidemics in animals. A better understanding of the natural hosts and genetic diversity of CoVs are needed to help mitigate these threats.

    OBJECTIVE: To design and evaluate a molecular diagnostic tool for detection and identification of all currently recognized and potentially future emergent CoVs from the Orthocoronavirinae subfamily.

    STUDY DESIGN AND RESULTS: We designed a semi-nested, reverse transcription RT-PCR assay based upon 38 published genome sequences of human and animal CoVs. We evaluated this assay with 14 human and animal CoVs and 11 other non-CoV respiratory viruses. Through sequencing the assay's target amplicon, the assay correctly identified each of the CoVs; no cross-reactivity with 11 common respiratory viruses was observed. The limits of detection ranged from 4 to 4 × 102 copies/reaction, depending on the CoV species tested. To assess the assay's clinical performance, we tested a large panel of previously studied specimens: 192 human respiratory specimens from pneumonia patients, 5 clinical specimens from COVID-19 patients, 81 poultry oral secretion specimens, 109 pig slurry specimens, and 31 aerosol samples from a live bird market. The amplicons of all RT-PCR-positive samples were confirmed by Sanger sequencing. Our assay performed well with all tested specimens across all sample types.

    CONCLUSIONS: This assay can be used for detection and identification of all previously recognized CoVs, including SARS-CoV-2, and potentially any emergent CoVs in the Orthocoronavirinae subfamily.

  4. Dengue infection associated hemophagocytic syndrome: Therapeutic interventions and outcome
    Wan Jamaludin WF, Periyasamy P, Wan Mat WR, Abdul Wahid SF
    J Clin Virol, 2015 Aug;69:91-5.
    PMID: 26209387 DOI: 10.1016/j.jcv.2015.06.004
    Infection associated hemophagocytic syndrome is increasingly recognized as a potentially fatal complication of dengue fever. It should be suspected with prolonged fever beyond seven days associated with hepatosplenomegaly, hyperferritinemia, worsening cytopenias and development of multiorgan dysfunction. Surge of similar pro-inflammatory cytokines observed in dengue associated hemophagocytic syndrome and multiorgan dysfunction may indicate they are part of related inflammatory spectrum. A proportion of patients recovered with supportive therapy, however most required interventions with corticosteroids, intravenous immunoglobulin or chemotherapy. We report three cases of dengue associated IAHS with good outcome following early recognition and treatment with dexamethasone and intravenous immunoglobulin.
  5. A phage-displayed cyclic peptide that interacts tightly with the immunodominant region of hepatitis B surface antigen
    Tan WS, Tan GH, Yusoff K, Seow HF
    J Clin Virol, 2005 Sep;34(1):35-41.
    PMID: 16087122
    The surface antigen (HBsAg) of hepatitis B virus (HBV) is highly conformational and generally evokes protective humoral immune response in human. A disulfide constrained random heptapeptide library displayed on the coat protein III of filamentous bacteriophage M13 was employed to select specific ligands that interact with HBsAg subtype ad. Fusion phages carrying the amino acid sequence ETGAKPH and other related sequences were isolated. The binding site of peptide ETGAKPH was located on the immunodominant region of HBsAg. An equilibrium binding assay in solution showed that the phage binds tightly to HBsAg with a relative dissociation constant (KDrel) of 2.9+/-0.9 nM. The phage bearing this peptide has the potential to be used as a diagnostic reagent and two assays for detecting HBsAg in blood samples are described.
  6. Hemophagocytosis in dengue: comprehensive report of six cases
    Tan LH, Lum LC, Omar SF, Kan FK
    J Clin Virol, 2012 Sep;55(1):79-82.
    PMID: 22789140 DOI: 10.1016/j.jcv.2012.06.005
    Hemophagocytic syndrome is a potentially fatal disorder. It is being increasingly reported but remained under-recognized in dengue. Most reported cases were in association with plasma leakage and shock but multi-organ impairment was also observed. We describe the time-lines of 6 cases of confirmed dengue with varying severities of hemophagocytosis. All had persistent fever, cytopenia and elevated transaminases with markedly elevated ferritin levels during and beyond the plasma leakage phase. Acute renal failure and central nervous system manifestation were observed in two patients. Morphological hemophagocytosis was demonstrated in three patients. All survivors showed clinical and biochemical resolution of hemophagocytosis indicating its transient nature. Persistence of fever and cytopenia together with multi-organ dysfunction, out of proportion to and beyond the plasma leakage phase should prompt clinicians to consider this phenomenon.
  7. A phage-displayed single chain variable fragment that interacts with hepatitis B core antigen: library construction, selection and diagnosis
    Tan GH, Yusoff K, Seow HF, Tan WS
    J Clin Virol, 2007 Jan;38(1):49-56.
    PMID: 17074533
    Phage display is an alternative method for constructing and selecting antibodies with desired specificity towards an antigen.
  8. Fulltext Absence of Melaka-virus in European children with respiratory disease
    Schildgen V, Rüngeler E, Tillmann R, Schildgen O
    J Clin Virol, 2008 Jul;42(3):295-6.
    PMID: 18359270 DOI: 10.1016/j.jcv.2008.02.003
  9. Analytical performance of HPV assays on vaginal self-collected vs practitioner-collected cervical samples: the SCoPE study
    Saville M, Hawkes D, Keung M, Ip E, Silvers J, Sultana F, et al.
    J Clin Virol, 2020 06;127:104375.
    PMID: 32361328 DOI: 10.1016/j.jcv.2020.104375
    BACKGROUND: In the last decade, human papillomavirus (HPV) testing has been evaluated extensively for cervical screening, with studies finding increased sensitivity compared to cytology. Another advantage of HPV based-screening is the ability to test vaginal samples that can be collected by women themselves. Self-collection has the potential to extend cervical screening coverage by increasing participation rates, particularly among women who are under-screened or have never screened. This could have a significant impact on cervical cancer prevention, as the majority of invasive cervical cancer cases occur among under-screened women. Both the Netherlands and Australia have transitioned their national programs from cytology to HPV as the primary screening test and both countries include a pathway for self-collection.

    OBJECTIVES: We evaluated the relative sensitivity for HPV detection of self-collection compared with practitioner-collected cervical specimens in the context of the Australian National Cervical Screening Program (NCSP).

    STUDY DESIGN: 303 women aged ≥18 years attending a single tertiary referral centre took their own sample using a flocked-swab, and then had a practitioner-collected sample taken at colposcopy. All samples were tested at a single laboratory on the six PCR-based HPV assays which can be utilised in the NCSP; Roche cobas 4800 and cobas, Abbott RealTime, BD Onclarity, Cepheid Xpert, and Seegene Anyplex.

    RESULTS: HPV16/18 results had high observed agreement between self- and practitioner-collected samples on all assays (range: 0.94-0.99), with good agreement for non-HPV16/18 oncogenic HPV types (range: 0.64-0.73).

    CONCLUSIONS: Self-collection for HPV-based cervical screening shows good concordance and relative sensitivity when compared to practitionercollected samples across assays in the NCSP.

  10. Chikungunya virus of Asian and Central/East African genotypes in Malaysia
    Sam IC, Chan YF, Chan SY, Loong SK, Chin HK, Hooi PS, et al.
    J Clin Virol, 2009 Oct;46(2):180-3.
    PMID: 19683467 DOI: 10.1016/j.jcv.2009.07.016
    BACKGROUND: Chikungunya virus (CHIKV) of the Central/East African genotype has caused large outbreaks worldwide in recent years. In Malaysia, limited CHIKV outbreaks of the endemic Asian and imported Central/East African genotypes were reported in 1998 and 2006. Since April 2008, an unprecedented nationwide outbreak has affected Malaysia.
    OBJECTIVE: To study the molecular epidemiology of the current Malaysian CHIKV outbreak, and to evaluate cross-neutralisation activity of serum from infected patients against isolates of Asian and Central/East African genotypes.
    STUDY DESIGN: Serum samples were collected from 83 patients presenting in 2008, and tested with PCR for the E1 gene, virus isolation, and for IgM. Phylogenetic analysis was performed on partial E1 gene sequences of 837bp length. Convalescent serum from the current outbreak and Bagan Panchor outbreak (Asian genotype, 2006) were tested for cross-neutralising activity against representative strains from each outbreak.
    RESULTS: CHIKV was confirmed in 34 patients (41.0%). The current outbreak strain has the A226V mutation in the E1 structural protein, and grouped with Central/East African isolates from recent global outbreaks. Serum cross-neutralisation activity against both Central/East African and Asian genotypes was observed at titres from 40 to 1280.
    CONCLUSIONS: The CHIKV strain causing the largest Malaysian outbreak is of the Central/East African genotype. The presence of the A226V mutation, which enhances transmissibility of CHIKV by Aedes albopictus, may explain the extensive spread especially in rural areas. Serum cross-neutralisation of different genotypes may aid potential vaccines and limit the effect of future outbreaks.
  11. Chikungunya, a paradigm of neglected tropical disease that emerged to be a new health global risk
    Rougeron V, Sam IC, Caron M, Nkoghe D, Leroy E, Roques P
    J Clin Virol, 2015 Mar;64:144-52.
    PMID: 25453326 DOI: 10.1016/j.jcv.2014.08.032
    Chikungunya virus (CHIKV) is an alphavirus of the Togaviridae family that causes chronic and incapacitating arthralgia in human populations. Since its discovery in 1952, CHIKV was responsible for sporadic and infrequent outbreaks. However, since 2005, global Chikungunya outbreaks have occurred, inducing some fatalities and associated with severe and chronic morbidity. Chikungunya is thus considered as an important re-emerging public health problem in both tropical and temperate countries, where the distribution of the Aedes mosquito vectors continues to expand. This review highlights the most recent advances in our knowledge and understanding of the epidemiology, biology, treatment and vaccination strategies of CHIKV.
  12. Unusual, neurological and severe dengue manifestations during the outbreak in Sri Lanka, 2017
    Ngwe Tun MM, Muthugala R, Nabeshima T, Rajamanthri L, Jayawardana D, Attanayake S, et al.
    J Clin Virol, 2020 04;125:104304.
    PMID: 32145478 DOI: 10.1016/j.jcv.2020.104304
    BACKGROUND: Sri Lanka experienced its largest dengue outbreak in 2017 with more than 185,000 dengue cases including at least 250 fatalities.

    OBJECTIVES: Our study aimed to characterize the clinical, immunological and virological features of confirmed dengue patients in Sri Lanka during the outbreak in 2017 when unusual manifestations of severe dengue were observed.

    STUDY DESIGN: Sera from 295 patients who were admitted to Teaching Hospital Kandy, Kandy, Sri Lanka between March 2017- January 2018 were subjected to NS1 antigen, IgM and IgG ELISAs, virus isolation, conventional and real time RT-PCR and next generation sequencing.

    RESULTS: Primary and secondary infections were detected in 48.5 % and 51.5 % of the study population, respectively. Two hundred twenty five DENV strains were isolated (219 DENV-2, one DENV-3, two DENV-4, two mixed infections of DENV-2 and -3 and one mixed infection of DENV-2 and -4). Unusual and severe manifestations such as encephalitis, encephalopathy, liver failure, kidney failure, myocarditis, Guillain-Barré syndrome and multi-organ failure were noted in 44 dengue patients with 11 deaths. The viraemia levels in patients with primary infection and unusual manifestations were significantly higher compared to those in patients with secondary infection. A new clade of DENV-2 Cosmopolitan genotype strains was observed with the strains closely related to those from China, Malaysia, Indonesia, Singapore and Taiwan.

    CONCLUSIONS: The new clade of DENV-2 cosmopolitan genotype observed in Sri Lanka in 2017 caused an unprecedented, severe dengue outbreak. The emergence of DENV-3 and DENV-4 in the 2017 outbreak might cause future outbreaks in Sri Lanka.

  13. Clinicians' diagnostic practice of dengue infections
    Ng CF, Lum LC, Ismail NA, Tan LH, Tan CP
    J Clin Virol, 2007 Nov;40(3):202-6.
    PMID: 17928264 DOI: 10.1016/j.jcv.2007.08.017
    BACKGROUND: Difficulties in the classification of dengue infection have been documented. Such difficulties could be due to the low awareness of the World Health Organization diagnostic guidelines among clinicians.
    OBJECTIVE: To study the diagnostic practices of clinicians in classifying patients as dengue fever (DF) or dengue haemorrhagic fever (DHF)/dengue shock syndrome (DSS) at the time of discharge during an outbreak.
    METHODS: A prospective descriptive study of clinical features and disease classification in adult and pediatric dengue patients in the University of Malaya Medical Centre.
    RESULTS: Five hundred and twenty adult and 191 pediatric patients were enrolled. Thrombocytopenia and evidence of plasma leakage were present in 8% of adult and 19% of pediatric patients. Of these, 93% and 49%, respectively, were given the discharge diagnoses of DF instead of DHF/DSS. Hemoconcentration, serous effusion and thrombocytopenia were not recognized in clinicians' discharge diagnosis of DHF/DSS for adult patients. The receiver operating characteristic (ROC) curve suggested a lack of consistency in the use of WHO guidelines in establishing DHF/DSS in adult patients, while implying otherwise for pediatric patients.
    CONCLUSION: DHF/DSS is an under-recognized condition by clinicians managing these patients. This can affect the case fatality rate of DHF/DSS and the economic burden of the disease. The lack of awareness in disease manifestations especially plasma leakage, can lead to delayed recognition of DHF/DSS.
    Study site: Outpatient department and inpatients, adult medical and pediatric wards, University Malaya Medical Center (UMMC), Kuala Lumpur, Malaysia
  14. Chikungunya infection in Malaysia: comparison with dengue infection in adults and predictors of persistent arthralgia
    Mohd Zim MA, Sam IC, Omar SF, Chan YF, AbuBakar S, Kamarulzaman A
    J Clin Virol, 2013 Feb;56(2):141-5.
    PMID: 23201456 DOI: 10.1016/j.jcv.2012.10.019
    Chikungunya virus (CHIKV) and dengue virus (DENV) co-circulate in areas endemic with the Aedes mosquito vectors. Both viruses cause similar illnesses which may be difficult to distinguish clinically. CHIKV is also associated with persistent arthralgia.
  15. Echovirus 7 associated encephalomyelitis
    Lum LC, Chua KB, McMinn PC, Goh AY, Muridan R, Sarji SA, et al.
    J Clin Virol, 2002 Jan;23(3):153-60.
    PMID: 11595594
    Hand, foot, and mouth disease (HFMD) is endemic in Malaysia. In 1997, a large outbreak of enterovirus 71 (EV-71) associated HFMD resulted in 41 deaths due to severe left ventricular dysfunction and central nervous system infection with extensive damage to the medulla and pons. The clinical presentation in all these patients were rapid cardio-respiratory decompensation leading to cardiac arrest. Another large outbreak of HFMD with 55 fatal cases and a similar clinical picture was reported in Taiwan in 1998. In 2000, an outbreak of HFMD resulted in the deaths of three children who had rapid cardio-respiratory decompensation and one child who survived a central nervous system infection.
  16. The emergence of Nipah virus, a highly pathogenic paramyxovirus
    Lo MK, Rota PA
    J Clin Virol, 2008 Dec;43(4):396-400.
    PMID: 18835214 DOI: 10.1016/j.jcv.2008.08.007
    Nipah virus first emerged in Malaysia and Singapore between 1998 and 1999, causing severe febrile encephalitis in humans with a mortality rate of close to 40%. In addition, a significant portion of those recovering from acute infection had relapse encephalitis and long-term neurological defects. Since its initial outbreak, there have been numerous outbreaks in Bangladesh and India, in which the mortality rate rose to approximately 70%. These subsequent outbreaks were distinct from the initial outbreak, both in their epidemiology and in their clinical presentations. Recent developments in diagnostics may expedite disease diagnosis and outbreak containment, while progress in understanding the molecular biology of Nipah virus could lead to novel therapeutics and vaccines for this deadly pathogen.
  17. Fulltext Clinical diagnosis of early dengue infection by novel one-step multiplex real-time RT-PCR targeting NS1 gene
    Kim JH, Chong CK, Sinniah M, Sinnadurai J, Song HO, Park H
    J Clin Virol, 2015 Apr;65:11-9.
    PMID: 25766980 DOI: 10.1016/j.jcv.2015.01.018
    BACKGROUND: Dengue is a mosquito-borne disease that causes a public health problem in tropical and subtropical countries. Current immunological diagnostics based on IgM and/or nonstructural protein 1 (NS1) antigen are limited for acute dengue infection due to low sensitivity and accuracy.
    OBJECTIVES: This study aimed to develop a one-step multiplex real-time RT-PCR assay showing higher sensitivity and accuracy than previous approaches.
    STUDY DESIGN: Serotype-specific primers and probes were designed through the multiple alignment of NS1 gene. The linearity and limit of detection (LOD) of the assay were determined. The assay was clinically validated with an evaluation panel that was immunologically tested by WHO and Malaysian specimens.
    RESULTS: The LOD of the assay was 3.0 log10 RNA copies for DENV-1, 2.0 for DENV-3, and 1.0 for DENV-2 and DENV-4. The assay showed 95.2% sensitivity (20/21) in an evaluation panel, whereas NS1 antigen- and anti-dengue IgM-based immunological assays exhibited 0% and 23.8-47.6% sensitivities, respectively. The assay showed 100% sensitivity both in NS1 antigen- and anti-dengue IgM-positive Malaysian specimens (26/26). The assay provided the information of viral loads and serotype with discrimination of heterotypic mixed infection.
    CONCLUSIONS: The assay could be clinically applied to early dengue diagnosis, especially during the first 5 days of illness and approximately 14 days after infection showing an anti-dengue IgM-positive response.
  18. Fulltext High proportion of norovirus infection and predominance of GII.3 [P12] genotype among the children younger than 5 in Sabah, Malaysian Borneo
    John JL, Mori D, Amit LN, Mosiun AK, Chin AZ, Ahmed K
    J Clin Virol, 2021 10;143:104968.
    PMID: 34509928 DOI: 10.1016/j.jcv.2021.104968
    Globally, norovirus (NoV) has become one of the important causes of acute gastroenteritis (AGE) in children. It is responsible for death of children younger than 5 years in developing countries. Although there is limited information and the rate of child mortality caused by diarrhea is low in Malaysia, the burden of diarrhea is high, especially in Sabah. NoV GI, GII and GIV genogroups are known to infect humans, and GII.4 is the predominant genotype distributed worldwide. Better understanding of the etiology of NoV will help to inform policies for prevention and control. The aim of this study was to determine the burden and genotype distribution of NoV in children younger than 5 years with AGE who attended health-care facilities in Sabah, Malaysia. Diarrhea stool samples were collected from 299 children with AGE and NoV was detected by amplifying the capsid and RNA-dependent RNA polymerase gene and reverse transcription-polymerase chain reaction (RT-PCR) analysis. Nucleotide sequencing of the amplicons was used for genotypes and phylogenetic analyses . NoV-positive stool samples were found in 17.7% (53/299) among which 13/53 (24.5%), 38/53 (71.7%), and 2/53 (3.8%) identified as NoV GI, GII and combination of GI and GII, respectively. The most common genotypes were GII.3 [P12] (80%) followed by GII.6 [P7] (13.3%), and GII.17 [P17] (6.7%). In the phylogenetic tree, all Sabahan NoV samples were shown to share ancestry with their respective genotype from predominantly East Asian countries and to some extent Australia and Europe. However, the Sabahan strains formed independent clusters with significant bootstrap values, indicating a clonal spread after the strains had entered Sabah.
  19. Inflammation of the external ear in acute chikungunya infection: Experience from the outbreak in Johor Bahru, Malaysia, 2008
    Javelle E, Tiong TH, Leparc-Goffart I, Savini H, Simon F
    J Clin Virol, 2014 Apr;59(4):270-3.
    PMID: 24556566 DOI: 10.1016/j.jcv.2014.01.011
    The re-emerging invalidating chikungunya disease has recently extended to temperate areas. Other alphaviruses can also present with febrile arthalgias. Dengue virus transmitted by the same species of mosquitoes may cocirculate, leading to dual infections and concurrent epidemics. Although these diseases share similar clinical features, their prognoses considerably differ. Prominent and prolonged articular disorders are more consistent with chikungunya virus, whereas haemorrhages make the gravity of dengue infection. Specific symptoms are required, especially when diagnostic tests are not available or performable at a large scale. Indeed, early clinical suspicion of a vector-borne disease is crucial to isolate the first cases in the course of an outbreak, and discrimination between arboviruses help to optimal management of patients. No specific chikungunya clinical sign has been yet reported. We highlight here the high prevalence (about 25%) of acute ear redness in infected people during the 2008 chikungunya outbreak in Jahor Bahru in Malaysia. Nine consenting patients are more precisely described. Ear chondritis could be sensitive diagnostic criterion of the acute stage of chikungunya, every physician - even in occidental non endemic areas - should be aware of.
  20. IPVS policy statement on HPV nucleic acid testing guidance for those utilising/considering HPV as primary precancer screening: Quality assurance and quality control issues
    Garland SM, Iftner T, Cuschieri K, Kaufmann AM, Arbyn M, de Sanjose S, et al.
    J Clin Virol, 2023 Feb;159:105349.
    PMID: 36584621 DOI: 10.1016/j.jcv.2022.105349
    We advise that only clinically validated HPV assays which have fulfilled internationally accepted performance criteria be used for primary cervical screening. Further, assays should be demonstrated to be fit for purpose in the laboratory in which they will ultimately be performed, and quality materials manuals and frameworks will be helpful in this endeavor. Importantly, there is a fundamental shortage of well validated, low-cost, low complexity HPV tests that have demonstrated utility in a near-patient setting; representing a significant challenge and focus for future development in order to reach the WHO's goal of eliminating cervical cancer.
Related Terms
    Try searching for something
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links