A novel syphilis Treponema pallidum lipoprotein peptide antigen diagnostic assay using red cell kodecytes in routine blood centre column agglutination testing platforms.

BACKGROUND AND OBJECTIVES: The detection of treponemal antibodies, which are used to make a diagnosis of syphilis, is important both for diagnostic purposes and as a mandatory blood donor test in most countries. We evaluated the feasibility of using Kode Technology to make syphilis peptide red cell kodecytes for use in column agglutination serologic platforms. MATERIALS AND METHODS: Candidate Kode Technology function-spacer-lipid (FSL) constructs were made for the Treponema pallidum lipoprotein (TmpA) of T. pallidum, using the peptide and FSL selection algorithms, and then used to make kodecytes. Developmental kodecytes were evaluated against a large range of syphilis antibody reactive and non-reactive samples in column agglutination platforms and compared against established methodologies. Overall, 150 reactive and 2072 non-reactive Syphicheck assay (a modified T. pallidum particle agglutination) blood donor samples were used to evaluate the agreement rate of the developed kodecyte assay. RESULTS: From three FSL-peptide candidate constructs, one was found to be the most suitable for diagnostics. Of 150 Syphicheck assay reactive samples, 146 were TmpA-kodecyte reactive (97.3% agreement), compared with 58.0% with the rapid plasmin reagin (RPR) assay for the same samples. Against the 2072 expected syphilis non-reactive samples the agreement rate for TmpA-kodecytes was 98.8%. CONCLUSION: TmpA-kodecytes are viable for use as cost-effective serologic reagent red cells for the detection of treponemal antibodies to diagnose syphilis with a high level of specificity in blood centres. This kodecyte methodology also potentially allows for introduction of the reverse-algorithm testing into low-volume laboratories, by utilizing existing transfusion laboratory infrastructure.

SARS-CoV-2 Peptide Bioconjugates Designed for Antibody Diagnostics.

In the near future, the increase in the number of required tests for COVID-19 antibodies is expected to be many hundreds of millions. Obviously, this will be done using a variety of analytical methods and using different antigens, including peptides. In this work, we compare three method variations for detecting specific immunoglobulins directed against peptides of approximately 15-aa of the SARS-CoV-2 spike protein. These linear peptide epitopes were selected using antigenicity algorithms, and were synthesized with an additional terminal cysteine residue for their bioconjugation. In two of the methods, constructs were prepared where the peptide (F, function) is attached to a negatively charged hydrophilic spacer (S) linked to a dioleoylphosphatidyl ethanolamine residue (L, lipid) to create a function-spacer-lipid construct (FSL). These FSLs were easily and controllably incorporated into erythrocytes for serologic testing or in a lipid bilayer deposited on a polystyrene microplate for use in an enzyme immunoassays (EIA). The third method, also an EIA, used polyacrylamide conjugated peptides (peptide-PAA) prepared by controlled condensation of the cysteine residue of the peptide with the maleimide-derived PAA polymer which were immobilized on polystyrene microplates by physisorption of the polymer. In this work, we describe the synthesis of the PAA and FSL peptide bioconjugates, design of test systems, and comparison of the bioassays results, and discuss potential reasons for higher performance of the FSL conjugates, particularly in the erythrocyte-based serologic assay.

COVID-19 antibody screening with SARS-CoV-2 red cell kodecytes using routine serologic diagnostic platforms.

BACKGROUND: The Coronavirus disease 2019 (COVID-19) pandemic is having a major global impact, and the resultant response in the development of new diagnostics is unprecedented. The detection of antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has a role in managing the pandemic. We evaluated the feasibility of using SARS-CoV-2 peptide Kode Technology-modified red cells (C19-kodecytes) to develop an assay compatible with existing routine serologic platforms. STUDY DESIGN AND METHODS: A panel of eight unique red cells modified using Kode Technology function-spacer-lipid constructs and bearing short SARS-CoV-2 peptides was developed (C19-kodecyte assay). Kodecytes were tested against undiluted expected antibody-negative and -positive plasma samples in manual tube and three column agglutination technology (CAT) platforms. Parallel analysis with the same peptides in solid phase by enzyme immunoassays was performed. Evaluation samples included >120 expected negative blood donor samples and >140 COVID-19 convalescent plasma samples, with independent serologic analysis from two centers. RESULTS: Specificity (negative reaction rate against expected negative samples) in three different CAT platforms against novel C19-kodecytes was >91%, which correlated with published literature. Sensitivity (positive reaction rate against expected positive convalescent, PCR-confirmed samples) ranged from 82% to 97% compared to 77% with the Abbott Architect SARS-CoV-2 IgG assay. Manual tube serology was less sensitive than CAT. Enzyme immunoassay results with some Kode Technology constructs also had high sensitivity. CONCLUSIONS: C19-kodecytes are viable for use as serologic reagent red cells for the detection of SARS-CoV-2 antibody with routine blood antibody screening equipment.

A comparison of the performance of saliva and nasopharyngeal nucleic acid amplification testing for the detection of SARS-CoV-2 in New Zealand.

AIM: To compare detection of SARS-CoV-2 from paired nasopharyngeal swabs (NPS) and saliva using molecular methods in common use for testing swabs in New Zealand. METHOD: Samples from individuals testing positive for SARS-CoV-2 in Auckland, Wellington and Dunedin were tested at the local laboratories using methods previously established for these sample types. RESULTS: One hundred and ninety-six paired samples from unique individuals were tested, with 46 (23%) positive from either sample type, of which 43/46 (93%) tested positive from NPS, and 42/46 (91%) from saliva, indicating no significant difference in performance between sample types (p=0.69). The average Δ Ct between saliva and nasopharyngeal swabs overall across the sample set was 0.22 cycles, indicating excellent concordance; however, the difference between NPS and saliva collected from the same individual was quite variable with up to 19 cycles difference between the sample types. CONCLUSION: We found that saliva is an equivalent sample type to nasopharyngeal swab for the detection of SARS-CoV-2 in our laboratories using multiple assay combinations and is suitable for use as a diagnostic and surveillance test for selected groups of individuals.

Distribution of HPV genotypes in women with cervical cancer in Auckland, New Zealand; a review of 50 specimens between 2000-2006.

BACKGROUND: In New Zealand, around two hundred women are diagnosed with cervical cancer annually, with approximately seventy deaths from cervical cancer per year. AIM: Our aim was to determine the distribution of oncogenic HPV genotypes in biopsy specimens from women with diagnosed cervical cancers in the Auckland region of New Zealand between 2000-2006. MATERIALS AND METHODS: Confirmed cases of cervical carcinoma were identified from the local pathology register, and representative tissue samples were taken from these blocks. Sections were deparaffinised, and DNA was extracted according to standard protocols. Samples were subject to PCR amplification using L1 consensus primer sets MY09/11 and GP5/6. Further type-specific amplification was performed on positive samples, using an in-house primer sequence based on target sequences within the E6 gene. Remaining samples were typed by a Linear Array Assay, or by DNA sequencing. RESULTS: HPV DNA was detected in 100% of cases. In 49/50 samples, the HPV genotype was identified, with a total of 14 different HPV genotypes detectable. Together HPV-16 and 18 were found in 41/49 cases (83.6%) either singly or in combination. DISCUSSION: Our findings suggest that the distribution of HPV genotypes in New Zealand is similar to that of other geographic areas. CONCLUSION: Ongoing surveillance is warranted to ensure appropriate genotype selection for prophylactic HPV vaccinations.

Evaluation of extraction and amplification assays for the detection of SARS-CoV-2 at Auckland Hospital laboratory during the COVID-19 outbreak in New Zealand.

Utilising diverse molecular platforms has formed a solid foundation in New Zealand's COVID-19 response. We evaluated multiple extraction and PCR assays for the detection of SARS-CoV-2. We included 65 positive samples which were run on the Panther Fusion using a laboratory developed test (LDT, E gene target). Where viral RNA was extracted by MagNA Pure (MP) 96 extraction platform or EpMotion 5075/Geneaid extraction kit, SARS-CoV-2 detection was performed on Light Cycler (LC) 480 using a LDT (E gene) or 3 commercial assays; Certest Viasure (Orf1ab, N genes) GenePro (E, RdRp genes) and A* Star Fortitude (proprietary target). Median Cts on LC 480 LDT for specimens (n = 9) extracted on MP 96 (26.6) were lower than on EpMotion (31.6) whereas median Cts for specimens (n = 10) extracted on the Panther Fusion LDT (23.1) were comparable with MP 96 /LC480 LDT (23.6). Specimens tested on Panther Fusion LDT (n = 28), extracted by MP 96, and amplified using commercial assays showed good concordance with a few exceptions; lower median Ct values were seen for 2 targets on GenePro (16.9, 21.5) and Viasure (19.5, 21.1) than for the Panther Fusion LDT (24.2) and A* Star Fortitude (25.6). Specimens tested on MP 96 (n = 18) had comparable results using commercial assays, with lower median Cts for Viasure (22.2, 23.7) compared with the LC 480 LDT (24.7), GenePro (24.7,25.7) and A*Fortitude (25.1) assays. The study provides an early assessment of the performance characteristics of 3 extraction methods for viral RNA and 5 PCR assays for the detection of SARS-CoV-2.

Human papillomavirus and oropharyngeal squamous cell carcinoma: a New Zealand cohort study.

BACKGROUND: Human papillomavirus (HPV)-related oropharyngeal squamous cell carcinomas (OPSCC) are clinically, epidemiologically and prognostically distinct from other OPSCCs. The incidence of HPV-related OPSCCs has increased significantly worldwide over the past few decades. However, no studies of OPSCC with direct molecular HPV testing has been conducted in New Zealand. AIMS: To estimate the proportion of OPSCCs attributable to HPV infections in a New Zealand population with a validated HPV testing algorithm. METHODS: HPV-status was determined by p16 immunohistochemistry and polymerase chain reaction (PCR) of both L1 and E6/7 genes on 55 OPSCCs diagnosed in 2010 and 2011 in Central and South Auckland. Baseline and survival analyses were performed according to HPV status. RESULTS: Forty-one (75%) of OPSCC tumours had HPV infections. There was 98% concordance between p16 immunohistochemistry and real-time E6/E7 PCR. After a median follow-up period of 2.6 years, patients with OPSCC of HPV aetiology had more favourable outcomes compared to patients with HPV-negative OPSCC (hazard ratio 0.14, P = 0.02) after adjustment for other variables. CONCLUSION: This study highlights the significant role that HPV plays in the aetiology of OPSCC in New Zealand, and confirms the high rate of accuracy of p16 immunostaining.