Rapid detection and subtyping of human papillomaviruses in condyloma acuminatum using loop-mediated isothermal amplification with hydroxynaphthol blue dye

Advanced technologies towards improved HPV diagnostics

Persistent infection with high-risk types of human papillomaviruses (HPV) is a major cause of cervical cancer, and an important factor in other malignancies, for example, head and neck cancer. Despite recent progress in screening and vaccination, the incidence and mortality are still relatively high, especially in low-income countries. The mortality and financial burden associated with the treatment could be decreased if a simple, rapid, and inexpensive technology for HPV testing becomes available, targeting individuals for further monitoring with increased risk of developing cancer. Commercial HPV tests available in the market are often relatively expensive, time-consuming, and require sophisticated instrumentation, which limits their more widespread utilization. To address these challenges, novel technologies are being implemented also for HPV diagnostics that include for example, isothermal amplification techniques, lateral flow assays, CRISPR-Cas-based systems, as well as microfluidics, paperfluidics and lab-on-a-chip devices, ideal for point-of-care testing in decentralized settings. In this review, we first evaluate current commercial HPV tests, followed by a description of advanced technologies, explanation of their principles, critical evaluation of their strengths and weaknesses, and suggestions for their possible implementation into medical diagnostics.

Detection of Five Types of HPV Genotypes Causing Anogenital Warts (Condyloma Acuminatum) Using PCR-Tm Analysis Technology

Objectives

Condyloma acuminatum (CA) is a common sexually transmitted disease caused by human papillomavirus (HPV) infection. We established a high-throughput, simple, low-cost, and accurate HPV-typing assay (polymerase chain reaction-melting temperature [PCR-Tm] analysis) to detect HPV in CA.

Materials and Methods

We detected 280 cervical scraping samples, including positive samples of HPV-6 (26), HPV-11 (12), HPV-16 (22), HPV-42 (18), HPV-43 (25), HPV-multiple (19), HPV- other type (58), and HPV-negative samples (100). All samples were compared by PCR-Tm analysis and a flow fluorescence hybridization assay. Sequencing was used to confirm the results of the PCR-Tm analysis.

Results

PCR-Tm analysis was specific for each genotype (HPV-6, HPV-11, HPV-16, HPV-42, and HPV-43). The sensitivity of the PCR-Tm analysis assay for each genotype was 10³, 10³, 10³, 10³, and 10² copies/reaction, respectively. Most of the 158 samples, including 58 HPV-other type positive and 100 HPV-negative samples tested by the flow fluorescence hybridization assay, were tested negative by PCR-Tm analysis. For the 122 remaining samples, 26 HPV-6, 12 HPV-11, 22 HPV-16, 18 HPV-42, 25 HPV-43, and 19 multiple HPV infections were detected through PCR-Tm analysis. In total, 25 HPV-6, 12 HPV-11, 21 HPV-16, 18 HPV-42, 25 HPV-43, and only 10 multiple HPV infections were detected by the flow fluorescence hybridization assay. The kappa coefficient for the analysis of PCR-Tm analysis and flow fluorescence hybridization assay was 0.940 (P < 0.0001), and the 95% confidence interval of the kappa coefficient was 90.3–97.7%.

Conclusion

PCR-Tm analysis enabled the detection of HPV-6, HPV-11, HPV-16, HPV-42, and HPV-43, including single and multiple infections.

Internal heating method of loop-mediated isothermal amplification for detection of HPV-6 DNA

Loop-mediated isothermal amplification (LAMP) is a promising diagnostic tool for genetic amplification, which is known for its rapid process, simple operation, high amplification efficiency, and excellent sensitivity. However, most of the existing heating methods are external for completion of molecular amplification with possibility of contamination of specimens. The present research provided an internal heating method for LAMP using magnetic nanoparticles (MNPs), which is called nano-LAMP. Near-infrared light with an excitation wavelength of 808 nm was employed as the heating source; hydroxy naphthol blue (HNB) was used as an indicator to conduct methodological research. We demonstrate that the best temperature was controlled at a working power of 2 W and 4.8 µg/µL concentration of nanoparticles. The lowest limit for the detection of HPV by the nano-LAMP method is 10² copies/mL, which was confirmed by a gel electrophoresis assay. In the feasibility investigation of validated clinical samples, all 10 positive HPV-6 specimens amplified by nano-LAMP were consistent with conventional LAMP methods. Therefore, the nano-LAMP detection method using internal heating of MNPs may bring a new vision to the exploration of thermostatic detection in the future.

A Case-Control Study of Photodynamic Therapy Combined with Thymosin in the Treatment of Condyloma Acuminatum in Anal Canal

A case-control study is performed in this paper to explore various possible effects and clinical value of the photodynamic therapy combined with thymosin for the treatment process of the condyloma acuminatum (CA) in the anal canal. For this purpose, a hundred (100) patients specifically with CA in the anal canal who were regularly treated in the hospital from February 2019 to April 2021 were recruited. The first group, that is, the control group, was treated with thymosin, whereas photodynamic therapy combined with thymosin was used as a treatment for the study group. The curative effect, clinical index, LTN, SP, TGF-β 1, TNF-α, CD3+, CD4+, CD8+, and the adverse reactions of incidence were compared between these groups. Moreover, 27 cases were observed to be obviously effective, 22 were observed to be effective, and a single case was observed to be ineffective. Thus, 98% is the total effective rate where a single case relapses. Likewise, in the control group, 15 cases were observed to be obviously effective, 28 effective, and 13 ineffective. Thus, 86% is the total rate of effectiveness where thirteen (13) cases relapse. We have observed that the study group has a higher rate of effectiveness than the control group and the rate of recurrence of the former group was slightly lower than that of the latter group, that is, the control group ( $P$  < 0.05). In addition, the time of symptom improvement, the amount of bleeding, the disappearance time of bloody stool, and the time of the first recurrence of the study group were observed to be lower than those of the control group ( $P$  < 0.05). In levels of LTN and SP, we have observed no or zero significant differences between these groups before treatment. However, LTN’s levels of both groups increased after the treatment, and SP’s level decreased. LTN’s level of the study group was observed to be higher than that of the other group, and SP’s level in the former group was lower than that in the latter group. Zero significant differences were observed in the TGF-β 1 and TNF-α’s levels between these groups before treatment, but the level of TGF-β 1 and TNF-α has increased and decreased, respectively, in both groups specifically after treatment. The level of TGF-β 1 in the former group was observed to be slightly higher than that in the latter group, that is, the control group, while TNF-α’s level in the study group was lower than that in the control group. We have not observed any significant difference in CD4+, CD3+, and CD8+ levels between these groups before treatment. However, after treatment, CD3+ and CD4+ levels increased, and the levels of CD8+ decreased in both groups, while CD3+ and CD4+ levels in the former group were evident to be higher than those in the latter group and the level of the CD8+ in the study group was observed to be lower than that in the control group. Finally, we compared the adverse reactions of incidence between these groups. There were 4 cases of tingling sensation and 1 case of redness and swelling in the group study along with a total incidence of 10%. There were 5 cases of tingling sensation and 2 cases of redness and swelling in the control group along with a total incidence of 14%. The incidence of adverse reactions in the study group was observed to be slightly lower than that in the control group, but a significant difference was not observed between these groups (χ2 = 0.378; $P$  > 0.05).

Rapid diagnosis of seven high-risk human papillomavirus subtypes by a novel loop-mediated isothermal amplification method

Current human papillomavirus (HPV) detection methods require complex instruments, skilled staff and have a high cost. Therefore, novel testing approaches are needed which are easy to implement, highly sensitive, and low cost. Loop-mediated isothermal amplification (LAMP) is an isothermal amplification technique. In this study, according to the conditions in China, a novel LAMP method for detecting seven high-risk HPV subtypes (16, 18, 33, 39, 45, 52, and 58) was designed and evaluated. The DNA from plasmid and cervical specimens was extracted using Chelex 100 and measured by qPCR and LAMP assay. LAMP products were observed under ultraviolet light. HPV sequences were successfully amplified and a plateau time of 19-75 min was maintained. The concentration of positive reactions ranged between 20 copies/μL and 200000 copies/μL. Additionally, there was no cross-reactivity between HPV16, 18, 33, 39, 45, 52, 58, 31, 35, 45, 51, 56, 59, 66, or 68. For clinical samples, the LAMP assay had high sensitivity and specificity for HPV16, 18, 33, 39, 45, 52, and 58. However, 5% (72/1447) of the samples tested yielded false-positive results. In conclusion, the novel LAMP assay for HPV16, 18, 33, 39, 45, 52, and 58 has high sensitivity and specificity, a low cost, and is simple and rapid to perform. The LAMP assay can improve HPV detection in resource-limited settings, especially in primary care hospitals and rural areas.

A colorimetric IsoPCR for the rapid and sensitive visual detection of high-risk HPV16 in clinical samples with hydroxynaphthol blue

HPV16 infection is found in more than 50 % of cervical cancer cases worldwide, triggering the development of numerous molecular techniques for viral diagnosis. The present study focuses on the development of a colorimetric IsoPCR for HPV16 DNA detection. The methodology combines the advantages of PCR and LAMP, while the most significant aspect of the new established methodology is the visual detection of amplification products through hydroxynapthol blue dye, thus minimizing the time and labor needed. An experimental cut-off value was tested through reconstitution experiments, while the specificity was evaluated by assessing clinical samples. The analytical sensitivity of the new colorimetric IsoPCR was found to be 0.1 viral DNA copy per reaction, while the specificity was 100 % for the detection of HPV16 DNA. The assay enabled the amplification of viral DNA in cases with viral load lower than 1 copy. In conclusion, the new established colorimetric IsoPCR can be regarded as an attractive molecular tool that facilitates the specific, rapid and highly sensitive visual detection of HPV16 DNA even at the very early stages of viral infection.

Development of a test kit for visual loop-mediated isothermal amplification of Salmonella in spiked ready-to-eat fruits and vegetables

The purpose of this study was to assemble two types of loop-mediated isothermal amplification (LAMP) kit that have the ability to visually detect Salmonella in ready-to-eat fruits and vegetables. The reaction results were obtained within 20-40 min after addition of DNA and can be discerned by the naked eye or an amplification plot. The stability of the LAMP wet kit was evident after multiple freezing and thawing cycles, and the one-step LAMP lyophilized kit was further evolved to allow ambient temperature transport for deployment in resource-limited settings. The cost-effective wet kit had the ability to detect minimum amounts of 1.8 CFU/ml Salmonella DNA without enrichment, while the sensitivity of the one-step LAMP lyophilized kit was only 9.8 × 10³ CFU/ml. They both have good anti-interference, as they were both able to detect 2.1 × 10² CFU/ml Salmonella mixed with 10⁶ CFU/ml four non-Salmonella strain mixture. Moreover, cucumber and lettuce that were contaminated with an initial inoculation of 1.7 CFU of Salmonella/10 g showed detection within a reaction time of 30 min after 10 h enrichment. The present research setup is a convenient and practical kit for Salmonella rapid detection that has good application prospects in food safety monitoring.

Simple Visualized Detection Method of Virulence-Associated Genes of Vibrio cholerae by Loop-Mediated Isothermal Amplification

Vibrio cholerae is a leading waterborne pathogenic bacterium worldwide. It can cause human cholera that is still pandemic in developing nations. Detection of V. cholerae contamination in drinking water and aquatic products is imperative for assuring food safety. In this study, a simple, sensitive, specific, and visualized method was developed based on loop-mediated isothermal amplification (LAMP) (designated sssvLAMP) to detect virulence-associated (ctxA, tcpA, hapA, mshA, pilA, and tlh) and species-specific (lolB) genes of V. cholerae. Three pairs of oligonucleotide primers (inner, outer, and loop primers) were designed and or synthesized to target each of these genes. The optimal conditions of the sssvLAMP method was determined, and one-step sssvLAMP reaction was performed at 65°C for 40 min. Positive results were simply read by the naked eye via color change (from orange to light green) under the visible light, or by the production of green fluorescence under the UV light (260 nm). The sssvLAMP method was more efficient in detecting 6.50 × 101-6.45 × 104-fold low number of V. cholerae cells, and more sensitive in V. cholerae genomic DNA (1.36 × 10-2-4.42 × 10-6 ng/reaction) than polymerase chain reaction (PCR) method. Among 52 strains of V. cholerae and 50 strains of non-target species (e.g., other Vibrios and common pathogens) examined, the sensitivity and specificity of the sssvLAMP method were 100% for all the target genes. Similar high efficiency of the method was observed when tested with spiked samples of water and aquatic products, as well as human stool specimens. Water from various sources and commonly consumed fish samples were promptly screened by this simple and efficient visualized method and diversified variation in the occurrence of the target genes was observed. V. cholerae strains could be mostly detected by the presence of hapA and tlh alone or in combination with other genes, indicating a variable risk of potentially pathogenic non-O1/O139 strains in edible food products. This novel LAMP method can be a promising tool to address the increasing need of food safety control of aquatic products.

Prevalence of human papillomavirus and subtype distribution in male partners of women with cervical intraepithelial neoplasia (CIN): a systematic review

BACKGROUND

Human Papillomavirus (HPV) infection is estimated to be the most common sexually transmitted infection. The present systematic review summarizes data regarding the prevalence of HPV and the distribution of subtypes in heterosexual male partners of women, who were diagnosed with any grade of cervical intraepithelial neoplasia (CIN).

METHODS

We conducted a systematic review of the literature by Medline and Google Scholar databases using the terms "Human Papillomavirus" or "HPV" plus "men" or "male partners" or "women with CIN". We included original published English-language articles published from 1/1/2000 until 1/1/2018 that had screened male partners of women with CIN using HPV DNA testing. We excluded studies that they overlapped with other included studies or were unrelated to the study subject.

RESULTS

We included a total of 12 publications, which reported the prevalence of HPV in free-clinical signs male partners of women with CIN. The largest proportion of the studies were from South America (seven studies), and the rest from Europe. The mean age of participants was 35.18 + - 3.47 years. HPV prevalence ranged from 12.9 to 86%; the total HPV prevalence among the studies was 49.1%, while ten out twelve studies (83.3%) demonstrated prevalence > 20%. Between the studies, the distribution of HPV subtypes varied on the basis of the method used, on the population and on the geographic region. A great variety of subtypes were detected, including 6, 11, 16, 18, 31, 33, 40, 42, 45, 51, 52, 53, 54, 56, 57, 58, 59, 61, 62, 66, 68, 81 and 83. In six studies the HPV 16 was the most frequent, while in two others the HPV 6 and HPV 83.

CONCLUSIONS

Until now, there are not precise screening or surveillance guidelines for the management of partners of women with CIN. This population is frequently colonized by various HPV subtypes and therefore need to be screened in an effort to reduce the infection in both sexes. The screening test could include detection/identification of HPV subtypes by a molecular assay, followed by peniscopy only in the positive cases.

British Journal of Biomedical Science in 2018: what have we learned?

In 2018 the British Journal of Biomedical Science published one guideline (in reproductive science) and 40 research articles in the various disciplines the comprise biomedical science. The latter were 24 original articles and 16 'In Brief' short reports. Of these, 23 are of note to only one of the sub-disciplines (seven each to biochemists and microbiologists, six to cell pathologists, and one each to cytologists, immunologists and reproductive scientists). Reflecting the increasing complexity of laboratory science, thirteen papers crossed one boundary (three papers each relevant to biochemists and immunologists, and to haematologists and biochemists), whilst four papers were relevant to three or more disciplines. Indeed, biochemical techniques were used in 18 papers, microbiological techniques in 9, whilst histopathology was relevant to 11 papers. Notably, 20 papers used techniques in chromosome analysis and molecular genetics. The present report will summarise key aspects of these publications that are of greatest relevance to laboratory scientists.