The feasibility of field collected pig oronasal secretions as specimens for the virologic surveillance of Japanese encephalitis virus

Virologic surveillance of Japanese encephalitis virus (JEV) relies on collecting pig blood specimens and adult mosquitoes in the past. Viral RNAs extracted from pig blood specimens suffer from low detecting positivity by reverse transcription PCR (RT-PCR). The oronasal transmission of the virus has been demonstrated in experimentally infected pigs. This observation suggested oronasal specimens could be useful source in the virus surveillance. However, the role of this unusual route of transmission remains unproven in the operational pig farm. In this study, we explore the feasibility of using pig oronasal secretions collected by chewing ropes to improve the positivity of detection in commercial pig farms. The multiplex genotype-specific RT-PCR was used in this study to determine and compare the positivity of detecting JEV viral RNAs in pig’s oronasal secretions and blood specimens, and the primary mosquito vector. Oronasal specimens had the overall positive rate of 6.0% (95% CI 1.3%–16.6%) (3/50) to 10.0% (95% CI 2.1%–26.5%) (3/30) for JEV during transmission period despite the negative results of all blood-derived specimens (n = 2442). Interestingly, pig oronasal secretions and female Culex tritaeniorhynchus mosquito samples collected from the same pig farm showed similar viral RNA positive rates, 10.0% (95% CI 2.1%–26.5%) (3/30) and 8.9% (95% CI 2.5%–21.2%) (4/45), respectively (p> 0.05). Pig oronasal secretion-based surveillance revealed the seasonality of viral activity and identified closely related genotype I virus derived from the mosquito isolates. This finding indicates oronasal secretion-based RT-PCR assay can be a non-invasive, alternative method of implementing JEV surveillance in the epidemic area prior to the circulation of virus-positive mosquitoes.

Mosquito-borne Japanese encephalitis virus (JEV) has either endemic or seasonal patterns of transmission in Asia and Australia. Most hosts infected by the virus remains asymptomatic but can result in severe encephalitis in humans and horses, and abortion or stillbirth in pregnant sows. Isolation of virus in adult mosquitoes or pig seroconversion has been used as an early indicator of upcoming JE outbreak in humans. Genotype identification of the virus is important since current human and domestic animal vaccines are all genotype III (GIII) specific. GIII vaccine elicited immunity has reduced cross-protections to genotypes other than GIII. Our virologic surveillance using pig’s oronasal secretion detected higher prevalence and earlier genotype I virus activity than using pig’s blood and mosquitoes, respectively. This proposed surveillance tool might be more effective that will allow the public health agency to properly implement the preventive measures, such as implementing mosquito control, encouraging booster vaccination, and encouraging the use of mosquito repellent, to reduce the impact of upcoming outbreak. Collection of pig’s oronasal secretion is non-invasive to pigs and less technically demanding to operators. Thus we propose the use of pig’s oronasal secretions as the novel source of specimens for virologic surveillance to replace the traditional pig blood or adult mosquito specimens to monitor and control JE outbreak/epidemic in the future.

Shielding of viruses such as SARS-Cov-2 from ultraviolet radiation in particles generated by sneezing or coughing: Numerical simulations of survival fractions

SARS-CoV-2 and other microbes within aerosol particles can be partially shielded from UV radiation. The particles refract and absorb light, and thereby reduce the UV intensity at various locations within the particle. Previously, we demonstrated shielding in calculations of UV intensities within spherical approximations of SARS-CoV-2 virions within spherical particles approximating dried-to-equilibrium respiratory fluids. The purpose of this paper is to extend that work to survival fractions of virions (i.e., fractions of virions that can infect cells) within spherical particles approximating dried respiratory fluids, and to investigate the implications of these calculations for using UV light for disinfection. The particles may be on a surface or in air. Here, the survival fraction (S) of a set of individual virions illuminated with a UV fluence (F, in J/m²) is assumed described by S(kF) = exp(-kF), where k is the UV inactivation rate constant (m²/J). The average survival fraction (S_p) of the simulated virions in a group of particles is calculated using the energy absorbed by each virion in the particles. The results show that virions within particles of dried respiratory fluids can have larger S_p than do individual virions. For individual virions, and virions within 1-, 5-, and 9-µm particles illuminated (normal incidence) on a surface with 260-nm UV light, the S_p = 0.00005, 0.0155, 0.22, and 0.28, respectively, when kF = 10. The S_p decrease to <10^-7, <10^-7, 0.077, and 0.15, respectively, for kF = 100. Results also show that illuminating particles with UV beams from widely separated directions can strongly reduce the S_p. These results suggest that the size distributions and optical properties of the dried particles of virion-containing respiratory fluids are likely important to effectively designing and using UV germicidal irradiation systems for microbes in particles. The results suggest the use of reflective surfaces to increase the angles of illumination and decrease the S_p. The results suggest the need for measurements of the S_p of SARS-CoV-2 in particles having compositions and sizes relevant to the modes of disease transmission.

The absence of coronavirus in expressed prostatic secretion in COVID-19 patients in Wuhan city

Due to the cellular entry of the novel coronavirus (SARS-CoV-2) modulated by angiotensin converting enzyme 2 (ACE2), the ACE2 bearing prostate is therefore hypothesized as a susceptible organ to COVID-19. To delineate whether the pathogenic SARS-CoV-2 of the coronavirus disease (COVID-19) could be detected in the expressed prostatic secretion (EPS), a total of ten male patients with confirmed COVID-19 were recruited. All patients were stratified into two groups: one group with positive nasopharyngeal swabbing SARS-CoV-2 within 3 days of the EPS taken day (PNS group, n = 3) and the other group with previously positive nasopharyngeal swabbing SARS-CoV-2 but turned negative before the taken day (PNNS group, n = 7). The COVID-19 patients showed elevated inflammatory indictors, i.e. C-reaction protein (3.28 (1.14, 33.33) mg/L), erythrocyte sedimentation rate (22.50 (8.00, 78.50) mm/h), and interleukin-6 (6.49 (4.96, 21.09) pg/ml). Serum IgM against SARS-CoV-2 was only positive in the PNS group, whereas serum IgG was positive for all patients. Furthermore, our data showed for the first time that none of the COVID-19 patients had positive SARS-CoV-2 RNA in EPS. To this end, this study found the negativity of SARS-CoV-2 in EPS and possibly exclude the sexual transmission of COVID-19.

SARS-CoV-2 Is Not Detectable in the Vaginal Fluid of Women With Severe COVID-19 Infection

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is spread mainly through respiratory droplets or direct contact. However, the infection condition of the genital system is unknown. Our aim in this study was to determine if SARS-CoV-2 is present in the vaginal fluid of women with coronavirus disease 2019 (COVID-19).

METHODS

Ten women with confirmed severe COVID-19 pneumonia admitted to the Tongji Zhongfa Hospital intensive care unit from 4 February 2020 through 24 February 2020 were included. Clinical records, laboratory results, and computed tomography examinations were retrospectively reviewed. The potential for genital infection was accessed by testing for the presence of SARS-CoV-2 in vaginal fluids obtained from vaginal swab samples. Reverse transcriptase polymerase chain reaction was used to confirm the SARS-CoV-2 infection in vaginal fluids.

RESULTS

The clinical characteristics of the 10 women were similar to those reported in other severe COVID-19 patients. All 10 patients were tested for SARS-CoV-2 in vaginal fluid, and all samples tested negative for the virus.

CONCLUSIONS

Findings from this small group of cases suggest that SARS-CoV-2 virus does not exist in the vaginal fluids of severe COVID-19 patients.

Antiretroviral adherence and virologic suppression in partnered and unpartnered HIV-positive individuals in southern Brazil

Background

An undetectable serum HIV-1 load is key to effectiveness of antiretroviral (ARV) therapy, which depends on adherence to treatment. We evaluated factors possibly associated with ARV adherence and virologic response in HIV-infected heterosexual individuals.

Methods

A cross-sectional study was conducted in 200 HIV-1 serodiscordant couples and 100 unpartnered individuals receiving ARV treatment at a tertiary hospital in southern Brazil. All subjects provided written informed consent, answered demographic/behavioral questionnaires through audio computer-assisted self-interviews (ACASI), and collected blood and vaginal samples for biological markers and assessment of sexually transmitted infections (STIs). HIV-negative partners were counseled and tested for HIV-1.

Results

The study population mean age was 39.9 years, 53.6% were female, 62.5% were Caucasian, 52.6% had incomplete or complete elementary education, 63.1% resided in Porto Alegre. Demographic, behavioral and biological marker characteristics were similar between couples and single individuals. There was an association between adherence reported on ACASI and an undetectable serum viral load (P<0.0001). Logistic regression analysis demonstrated that single-tablet ARV-regimens were independently associated with adherence (OR = 2.3; 95CI%: 1.2–4.4; P = 0.011) after controlling for age, gender, education, marital status, personal income, ARV regimen, and median time of ARV use. A positive correlation between genital secretion PCR results and serum viral load was significant in the presence of STIs (r = 0.359; P = 0.017). Although HIV PCR detection in vaginal secretions was more frequent in women with detectable viremia (9/51, 17.6%), it was also present in 7 of 157 women with undetectable serum viral loads (4.5%), p = 0.005.

Conclusions

ARV single tablet regimens are associated with adherence. Detectable HIV-1 may be present in the genital secretions of women with undetectable viremia which means there is potential for HIV transmission in adherent individuals with serologic suppression.

Comparative analysis of viral shedding in pediatric and adult subjects with central nervous system-associated enterovirus infections from 2013 to 2015 in Switzerland

BACKGROUND

Several enterovirus (EV) genotypes can result in aseptic meningitis, but their routes of access to the central nervous system remain to be elucidated and may differ between the pediatric and adult populations.

OBJECTIVE

To assess the pattern of viral shedding in pediatric and adult subjects with acute EV meningitis and to generate EV surveillance data for Switzerland.

STUDY DESIGN

All pediatric and adult subjects admitted to the University Hospitals of Geneva with a diagnosis of EV meningitis between 2013 and 2015 were enrolled. A quantitative EV real-time reverse transcriptase (rRT)-PCR was performed on the cerebrospinal fluid (CSF), blood, stool, urine and respiratory specimens to assess viral shedding and provide a comparative analysis of pediatric and adult populations. EV genotyping was systematically performed.

RESULTS

EV positivity rates differed significantly between pediatric and adult subjects; 62.5% of pediatric cases (no adult case) were EV-positive in stool and blood for subjects for whom these samples were all collected. Similarly, the EV viral load in blood was significantly higher in pediatric subjects. Blood C-reactive protein levels were lower and the number of leucocytes/mm³ in the CSF were higher in non-viremic than in viremic pediatric subjects, respectively. A greater diversity of EV genotypes was observed in pediatric cases, with a predominance of echovirus 30 in children ≥3 years old and adults.

CONCLUSION

In contrast to adults, EV-disseminated infections are predominant in pediatric subjects and show different patterns of EV viral shedding. This observation may be useful for clinicians and contribute to modify current practices of patient care.

HIV pre-exposure prophylaxis for women and infants prevents vaginal and oral HIV transmission in a preclinical model of HIV infection

BACKGROUND

Approximately 1.5 million HIV-positive women become pregnant annually. Without treatment, up to 45% will transmit HIV to their infants, primarily through breastfeeding. These numbers highlight that HIV acquisition is a major health concern for women and children globally. They also emphasize the urgent need for novel approaches to prevent HIV acquisition that are safe, effective and convenient to use by women and children in places where they are most needed.

METHODS

4'-Ethynyl-2-fluoro-2'-deoxyadenosine, a potent NRTI with low cytotoxicity, was administered orally to NOD/SCID/γc-/- mice and to bone marrow/liver/thymus (BLT) humanized mice, a preclinical model of HIV infection. HIV inhibitory activity in serum, cervicovaginal secretions and saliva was evaluated 4 h after administration. 4'-Ethynyl-2-fluoro-2'-deoxyadenosine's ability to prevent vaginal and oral HIV transmission was evaluated using highly relevant transmitted/founder viruses in BLT mice.

RESULTS

Strong HIV inhibitory activity in serum, cervicovaginal secretions and saliva obtained from animals after a single oral dose of 4'-ethynyl-2-fluoro-2'-deoxyadenosine (10 mg/kg) demonstrated efficient drug penetration into relevant mucosal sites. A single daily oral dose of 4'-ethynyl-2-fluoro-2'-deoxyadenosine resulted in efficient prevention of vaginal and oral HIV transmission after multiple high-dose exposures to transmitted/founder viruses in BLT humanized mice.

CONCLUSIONS

Our data demonstrated that 4'-ethynyl-2-fluoro-2'-deoxyadenosine efficiently prevents both vaginal and oral HIV transmission. Together with 4'-ethynyl-2-fluoro-2'-deoxyadenosine's relatively low toxicity and high potency against drug-resistant HIV strains, these data support further clinical development of 4'-ethynyl-2-fluoro-2'-deoxyadenosine as a potential pre-exposure prophylaxis agent to prevent HIV transmission in women and their infants.

Ebola Virus Shedding and Transmission: Review of Current Evidence

BACKGROUND

The magnitude of the 2013-2016 Ebola virus disease outbreak in West Africa was unprecedented, with >28 500 reported cases and >11 000 deaths. Understanding the key elements of Ebola virus transmission is necessary to implement adequate infection prevention and control measures to protect healthcare workers and halt transmission in the community.

METHODS

We performed an extensive PubMed literature review encompassing the period from discovery of Ebola virus, in 1976, until 1 June 2016 to evaluate the evidence on modes of Ebola virus shedding and transmission.

FINDINGS

Ebola virus has been isolated by cell culture from blood, saliva, urine, aqueous humor, semen, and breast milk from infected or convalescent patients. Ebola virus RNA has been noted in the following body fluids days or months after onset of illness: saliva (22 days), conjunctiva/tears (28 days), stool (29 days), vaginal fluid (33 days), sweat (44 days), urine (64 days), amniotic fluid (38 days), aqueous humor (101 days), cerebrospinal fluid (9 months), breast milk (16 months [preliminary data]), and semen (18 months). Nevertheless, the only documented cases of secondary transmission from recovered patients have been through sexual transmission. We did not find strong evidence supporting respiratory or fomite-associated transmission.

Inactivated chimeric porcine circovirus (PCV) 1-2 vaccines based on genotypes 2b and 2d exhibit similar immunological effectiveness in protecting pigs against challenge with PCV2b strain 0233

Porcine circovirus type 2 (PCV2) is subdivided into four genotypes: PCV2a, PCV2b, PCV2c and PCV2d. Here, for the first time, we compared the efficacy of two experimental inactivated chimeric PCV1-2 vaccines based on genotypes 2b and 2d. Seventeen 3-week-old pigs were divided randomly into four groups. Group 1 and 2 pigs were inoculated with genotype 2b- and 2d-based inactivated vaccines, respectively. At 28 days post-vaccination (DPV), pigs in groups 1-3 were challenged with the PCV2b 0233 strain. All experimental pigs were necropsied at 21 days post-challenge (DPC). Pigs vaccinated with the genotype 2b- or 2d-based vaccine had high antibody titres and lower PCV2b copy numbers in samples of sera, faeces and nasal secretions compared with pigs in the unvaccinated challenge group. Interestingly, we detected no DNA from the challenge strain in the superficial inguinal lymph nodes of the pigs immunized with the PCV2b vaccine, while one pig in the PCV2d- immunized group had detectable DNA from the challenge strain at 21 DPC. We found no significant differences in the humoral immune response, PCV2b load, or PCV-related microscopic lesions between the two vaccinated groups post-challenge. Therefore, both vaccines were equally effective at inducing immunity against challenge with PCV2b strain 0233.

Robust Cytokine and Chemokine Response in Nasopharyngeal Secretions: Association With Decreased Severity in Children With Physician Diagnosed Bronchiolitis

BACKGROUND

Bronchiolitis causes substantial disease in young children. Previous findings had indicated that a robust innate immune response was not associated with a poor clinical outcome in bronchiolitis. This study tested the hypothesis that increased concentrations of cytokines and chemokines in nasal wash specimens were associated with decreased severity in bronchiolitis.

METHODS

Children <24 months old who presented to the emergency department with signs and symptoms of bronchiolitis were eligible for enrollment. Nasal wash specimens were analyzed for viral pathogens and cytokine/chemokine concentrations. These results were evaluated with regard to disposition.

RESULTS

One hundred eleven children with bronchiolitis were enrolled. A viral pathogen was identified in 91.9% of patients (respiratory syncytial virus in 51.4%, human rhinovirus in 11.7%). Higher levels of cytokines and chemokines (interferon [IFN] γ; interleukin [IL] 4, 15, and 17; CXCL10; and eotaxin) were significantly associated with a decreased risk of hospitalization. IL-17, IL-4, IFN-γ, and IFN-γ-inducible protein 10 (CXCL10 or IP-10) remained statistically significant in the multivariate analyses.

CONCLUSIONS

The cytokines and chemokines significantly associated with decreased bronchiolitis severity are classified in a wide range of functional groups (T-helper 1 and 2, regulatory, and chemoattractant). The involvement of these functional groups suggest that a broadly overlapping cytokine/chemokine response is required for control of virus-mediated respiratory disease in young children.

Systematic review of the literature on viral persistence and sexual transmission from recovered Ebola survivors: evidence and recommendations

OBJECTIVE

The main aim of this article is to present a comprehensive, systematic review on evidence of sexual transmission from Ebola survivors and persistence of Ebola virus in body fluids of relevance to sexual transmission, and additionally to review condom effectiveness against sexual transmission of Ebola.

DESIGN

We performed a systematic review of viral persistence in body fluids of relevance to sexual transmission of Ebola survivors and evidence of sexual transmission of Ebola, and carried out a targeted review of condom effectiveness.

RESULTS

We identified nine published original articles presenting results on persistence of Ebola virus in relevant body fluids, or reporting suspect sexual transmission from Ebola survivors. We also included unpublished reports from the current 2014/2015 Ebola epidemic in West Africa. We found no articles reporting on condom effectiveness, but have included a targeted review on general condom efficacy and effectiveness.

CONCLUSIONS

We conclude that the risk of sexual transmission from people who have recovered from Ebola cannot be ruled out. We found the longest duration of persistent Ebola RNA in a relevant body fluid from a survivor, to be reported from a man in Sierra Leone who had reverse transcriptase PCR (RT-PCR) positive semen 284 days after symptom onset. In line with current WHO recommendations. We recommend that men are offered the possibility to test their semen regularly for presence of Ebola RNA from 3 months post-symptom onset. Safe sex practices including sexual abstinence, or else condom use, are recommended by WHO until semen has tested negative twice, or in absence of testing for at least 6 months post-symptom onset. Based on evidence reviewed, we conclude that male and female latex condoms offer some protection against EBOV compared to no condom use. Survivors should be offered access to care and prevention, in order to provide them with possibilities to mitigate any risks that may occur, and efforts should be linked to destigmatising activities.

HIV-1 specific IgA detected in vaginal secretions of HIV uninfected women participating in a microbicide trial in Southern Africa are primarily directed toward gp120 and gp140 specificities

Background

Many participants in microbicide trials remain uninfected despite ongoing exposure to HIV-1. Determining the emergence and nature of mucosal HIV-specific immune responses in such women is important, since these responses may contribute to protection and could provide insight for the rational design of HIV-1 vaccines.

Methods and Findings

We first conducted a pilot study to compare three sampling devices (Dacron swabs, flocked nylon swabs and Merocel sponges) for detection of HIV-1-specific IgG and IgA antibodies in vaginal secretions. IgG antibodies from HIV-1-positive women reacted broadly across the full panel of eight HIV-1 envelope (Env) antigens tested, whereas IgA antibodies only reacted to the gp41 subunit. No Env-reactive antibodies were detected in the HIV-negative women. The three sampling devices yielded equal HIV-1-specific antibody titers, as well as total IgG and IgA concentrations. We then tested vaginal Dacron swabs archived from 57 HIV seronegative women who participated in a microbicide efficacy trial in Southern Africa (HPTN 035). We detected vaginal IgA antibodies directed at HIV-1 Env gp120/gp140 in six of these women, and at gp41 in another three women, but did not detect Env-specific IgG antibodies in any women.

Conclusion

Vaginal secretions of HIV-1 infected women contained IgG reactivity to a broad range of Env antigens and IgA reactivity to gp41. In contrast, Env-binding antibodies in the vaginal secretions of HIV-1 uninfected women participating in the microbicide trial were restricted to the IgA subtype and were mostly directed at HIV-1 gp120/gp140.

The relevance of respiratory viral infections in the exacerbations of chronic obstructive pulmonary disease—a systematic review

BACKGROUND

Despite the increasing knowledge on the role of viruses in exacerbations of COPD (AECOPD), it is less clear which viruses are involved and to what extent they contribute to exacerbations. This review aims to systematically combine and evaluate the available literature of the prevalence of respiratory viruses in patients with AECOPD, detected by PCR.

METHODS

An electronic search strategy was performed on PubMed and Embase and reference lists were screened for eligible studies. Cross-sectional, prospective studies and case-control studies were included. The primary outcome measure was the prevalence of respiratory viruses (adenovirus, bocavirus, coronavirus, EBV, hMPV, influenza, parainfluenza, rhino-/enterovirus, RSV) in respiratory secretions of patients during an AECOPD. Secondary outcomes were the odds of the presence of the viruses in different respiratory secretions and the odds of the presence of viruses in upper and lower respiratory tract (URT/LRT) samples.

RESULTS

Nineteen studies with 1728 patients were included. Rhino-/enteroviruses (16.39%), RSV (9.90%) and influenza (7.83%) were the most prevalent viruses detected with lower detection rates of coronaviruses (4.08%) and parainfluenza (3.35%). Adenovirus (2.07%), hMPV (2.78%) and bocaviruses (0.56%) appear to be rare causative agents of AECOPD. Definitive conclusions regarding the role of EBV cannot be made. Seven of the eight analyzed viruses had a higher prevalence in LRT samples. Coronaviruses were detected more frequently in the URT.

CONCLUSIONS

Respiratory viruses are frequently detected in both URT and LRT samples in AECOPD with rhino-/enteroviruses, RSV and influenza viruses the most prevalent viruses. Detection rates vary between the two sites for different viruses.

Recent developments in human cytomegalovirus diagnosis

Since the early 1990s, great efforts have been made in the field of human cytomegalovirus (HCMV) diagnosis. Besides HCMV diagnosis in immunosuppressed patients (solid organ transplant recipients, hematopoietic stem cell transplant patients and AIDS patients), diagnosis in connection with congenital HCMV infection is of great interest. This review focuses on the development and clinical utility of serological assays, as well as on virological tests (molecular and nonmolecular assays). Interpretation of these tests is strongly dependent on the patient group (solid organ transplant recipients and hematopoietic stem cell transplant patients) and whether the tests are used for screening, risk stratification or diagnosis. Furthermore, a better understanding of HCMV infection has led to new approaches in HCMV diagnosis and monitoring. Thus, assays for viral resistance testing and assays for monitoring the HCMV-specific cellular immune response are increasingly important for the guidance of antiviral therapy.

HIV-DNA in the genital tract of women on long-term effective therapy is associated to residual viremia and previous AIDS-defining illnesses

OBJECTIVES

To assess the impact of long-term combined antiretroviral therapy (cART) on HIV-RNA and HIV-DNA levels in cervicovaginal secretions of HIV-1-infected women with sustained undetectable plasma RNA viral load (PVL); to explore factors predictive of residual viral shedding; and to evaluate the risk of heterosexual transmission.

METHODS

Women with undetectable PVL (<50 copies/mL) for >6 months were included in this cross-sectional study. HIV-RNA and HIV-DNA were measured in blood and cervicovaginal lavage fluid (CVL). Women were systematically tested for genital infections. The risk of transmission to male partners during unprotected intercourse was estimated.

RESULTS

Eighty-one women composed the study population: all had HIV-RNA <40 copies/mL in CVL. HIV-DNA was detectable in CVL of 29/78 patients (37%). There was a weak positive correlation between HIV-DNA levels in PBMCs and CVL (r = 0.20; p = 0.08). In multivariate analysis, two factors were associated with HIV-DNA detection in CVL: previous AIDS-defining illnesses (OR = 11; 95%CI = 2-61) and current residual viremia (20<PVL<50 cp/mL) (OR = 3.4; 95%CI = 1.1-10.9). Neither the classes of cART regimen nor the presence of genital bacterial or fungal colonization were associated with HIV-DNA detection in CVL. Twenty-eight percent of the women had unprotected intercourse with their regular HIV-seronegative male partner, for between 8 and 158 months. None of their male partners became infected, after a total of 14 000 exposures.

CONCLUSION

In our experience, HIV-RNA was undetectable in the genital tract of women with sustained control of PVL on cART. HIV-DNA shedding persisted in about one third of cases, with no substantial evidence of residual infectiousness.

[Application of FilmArray assay for detection of respiratory tract infections in immunocompromised persons]

INTRODUCTION

A variety of viruses and bacteria are responsible for acute upper and lower respiratory tract infections worldwide. Severe and even fatal disease can occur especially in group ofimmunocompromised individuals. Accurate pathogen identification allows clinicians to determine the need for ancillary diagnostic testing, antibacterial and/or antiviral therapy and can motivate decisions regarding hospitalization and infection control measures.

METHODS

We compared the diagnostic performance of FilmArray Respiratory Panel highly multiplexed nucleic acid amplification test with previous used direct immunofluorescence assay. Both assays were performed on a panel of 6 nasopharyngeal-secretion specimens and 6 BALF samples, collected from 12 patients, subjected to allogeneic haematological stem cells transplantation, with lower respiratory tract symptoms.

RESULTS AND CONCLUSIONS

Among viruses detectable by both assays were especially influenzaA virus, parainfluenza viruses type 3 and respiratory syncytial virus. In conclusion, the FilmArray assay is rapid and extremely user-friendly system, with results available in just over one hour with almost no labor involved. In few laboratories its low throughput and qualitative results may be a disadvantage in some clinical settings.

Epidemiology of 2009 pandemic influenza A virus subtype H1N1 among Kenyans aged 2 months to 18 years, 2009-2010

BACKGROUND

The US Army Medical Research Unit-Kenya (USAMRU-K) conducts surveillance for influenza-like illness (ILI) in Kenya. We describe the temporal and geographic progression of A(H1N1)pdm09 as it emerged in Kenya and characterize the outpatient population with A(H1N1)pdm09 infection.

METHODS

We included patients with ILI aged 2 months to 18 years enrolled during June 2009-August 2010. Respiratory specimens were tested by real-time reverse-transcription polymerase chain reaction for influenza virus. Patients with A(H1N1)pdm09 infection were compared to those with seasonal influenza A virus infection and those with ILI who had no virus or a virus other than influenza virus identified (hereafter, "noninfluenza ILI").

RESULTS

Of 4251 patients with ILI, 193 had laboratory-confirmed A(H1N1)pdm09 infection. The first pandemic influenza case detected by USAMRU-K surveillance was in August 2009; peak activity nationwide occurred during October-November 2009. Patients with A(H1N1)pdm09 infection were more likely to be school-aged, compared with patients with seasonal influenza A virus infection (prevalence ratio [PR], 2.0; 95% confidence interval [CI], 1.3-3.1) or noninfluenza ILI (PR, 3.2; 95% CI, 2.4-4.3).

CONCLUSIONS

USAMRU-K ILI surveillance detected the geographic and temporal distribution of pandemic influenza in Kenya. The age distribution of A(H1N1)pdm09 infections included more school-aged children, compared with seasonal influenza A virus infection and noninfluenza ILI.

[Contemporary clinical diagnostics of respiratory tract infections]

The patient population at risk pulmonary infections has increased during the last decade. The spectrum of organisms causing infections has also grown, most of them are viruses Baseline diagnostic assessment include history, clinical examination, radiography and measurements of procalcitonin (PCT), highly sensitive C-reactive protein (hsCRP) and leukocyte count. PCT represents a good biological marker for difficult diagnoses in critically ill patients and is superior to CRP. Chest x-rays seldom give enough information to determine the exact cause of the abnormality, but they can help a doctor to determine whether and which other tests are needed to make a diagnosis. Microbiologic advances have helped to facilitate the laboratory diagnosis of some pathogens. Cultures of respiratory specimens are some times useful but the gold standard for diagnosis of pulmonary infection is blood culture. Immunoassays are available for the detection of antigen in nasopharyngeal secretions (respiratory syncytial virus, influenza), and in urine (Legionella spp.). Rapid-culture techniques are available for the culture and detection of various viruses. Recently PCR-based techniques and RT-PCR assist in the detection of Legionella, Chlamydia, Mycoplasma, Pneumocystis carinii and mycobacteria species. This article presents a practical approach to the differential diagnosis of pulmonary infections.

Persistence of adenovirus nucleic acids in nasopharyngeal secretions: a diagnostic conundrum

BACKGROUND

Polymerase chain reaction (PCR) assays increase the rate of viral detection in clinical specimens, compared with conventional virologic methods. Studies suggest that PCR may detect virus nucleic acid (NA) that persists in the respiratory tract.

METHODS

We analyzed virologic data from children having frequent upper respiratory infections (URI), who were followed up in a longitudinal study. Nasopharyngeal secretions were collected at URI onset and when acute otitis media was diagnosed; virus studies were performed using conventional diagnostics and PCR. Repeated presence of adenovirus by PCR was further studied by sequencing and phylogenetic analysis.

RESULTS

Of 581 URI episodes in 76 children, 510 viruses were detected. Of the viruses detected by PCR, 15% were those detected previously; repeated positives occurred most frequently with adenovirus. Sequencing results were available in 13 children with repeated adenovirus detection; the following 4 patterns of infection were identified (16 instances): (1) adenovirus of the same serotype and strain detected continuously (n = 8 instances), (2) adenovirus of different serotypes detected during sequential URI episodes (n = 3), (3) adenovirus of the same serotype but different strains detected during sequential URI episodes (n = 3), and (4) adenovirus of the same serotype and strain detected intermittently (n = 2).

CONCLUSIONS

Among children with frequent URIs, repeated positive PCR results for adenovirus NA may represent a new serotype/strain, or persistence of viral NA. Results must be interpreted with caution; clinical correlation and presence of other viruses are important. Further longitudinal studies of children during and after infection are required for better understanding of the clinical significance of positive PCR tests for adenovirus NA in the respiratory tract.

Metagenomic sequencing for virus identification in a public-health setting

The use of metagenomics for virus discovery in clinical samples has opened new opportunities for understanding the aetiology of unexplained illness. This study explores the potential of this sequence-independent approach in a public-health setting, by systematic analysis of samples cultured from patients with unexplained illness through a combination of PCR-based assays and viral metagenomics. In total, 1834 cell-culture isolates were collected between 1994 and 2007 through the Enterovirus Surveillance programme in the Netherlands. During the 13 year period, seven samples that exhibited reproducible cytopathogenic effects in cell culture tested negative in standard PCR assays for a range of viruses. In order to fill the diagnostic gap, viral metagenomics was applied to these culture supernatants, resulting in the rapid identification of viruses in all of the samples. The unexplained samples contained BK polyomavirus, herpes simplex virus, Newcastle disease virus and the recently discovered Saffold viruses (SAFV) (which dominated the unexplained samples; n=4). The full genomic sequences of four SAFV genotype 3 (SAFV-3) viruses, which share 88-93 % nucleotide identity with known SAFV-3 viruses, are reported. Further screening for SAFV in additional cultured, unidentified clinical isolates from 2008 and 2009 resulted in identification of another SAFV-positive sample. Although the pathogenicity of the identified viruses has not been established, this study demonstrates that viral metagenomics is a powerful tool that can be integrated into public-health monitoring efforts to investigate unidentified viruses in cell cultures from clinical isolates where standard PCR assays fail to detect viruses.

[Study of virus content of Herpes viridae family in parotid secretion of patients with inflammatory-dystrophic diseases of salivary glands]

The study is devoted to disclose the interrelation between Herpes viridae family carriage and inflammatory-dystrophic diseases of salivary glands (SG). It was shown that inflammatory and dystrophic diseases of SG in observed patients run on the background of latent and active chronic herpes-virus infection. In the case the frequency of disclosure and content of antibodies to nuclear protein of Epstein-Barr virus in the peripheral blood serum in patients with different inflammatory and dystrophic SG diseases were statistically significantly higher and antibodies to simple 1st type virus and cytomegalovirus lower than in patients with different types of maxillofacial region pathology without SG involvement. The immediate contamination of parotid secretion by virus of Herpes viridae family was detected with the help of polymerase chain reaction in 18% of patients with SG diseases.

Streptococcus pneumoniae coinfection is correlated with the severity of H1N1 pandemic influenza

Background

Initial reports in May 2009 of the novel influenza strain H1N1pdm estimated a case fatality rate (CFR) of 0.6%, similar to that of seasonal influenza. In July 2009, however, Argentina reported 3056 cases with 137 deaths, representing a CFR of 4.5%. Potential explanations for increased CFR included virus reassortment or genetic drift, or infection of a more vulnerable population. Virus genomic sequencing of 26 Argentinian samples representing both severe and mild disease indicated no evidence of reassortment, mutations associated with resistance to antiviral drugs, or genetic drift that might contribute to virulence. Furthermore, no evidence was found for increased frequency of risk factors for H1N1pdm disease.

Methods/Principal Findings

We examined nasopharyngeal swab samples (NPS) from 199 cases of H1N1pdm infection from Argentina with MassTag PCR, testing for 33 additional microbial agents. The study population consisted of 199 H1N1pdm-infected subjects sampled between 23 June and 4 July 2009. Thirty-nine had severe disease defined as death (n = 20) or hospitalization (n = 19); 160 had mild disease. At least one additional agent of potential pathogenic importance was identified in 152 samples (76%), including Streptococcus pneumoniae (n = 62); Haemophilus influenzae (n = 104); human respiratory syncytial virus A (n = 11) and B (n = 1); human rhinovirus A (n = 1) and B (n = 4); human coronaviruses 229E (n = 1) and OC43 (n = 2); Klebsiella pneumoniae (n = 2); Acinetobacter baumannii (n = 2); Serratia marcescens (n = 1); and Staphylococcus aureus (n = 35) and methicillin-resistant S. aureus (MRSA, n = 6). The presence of S. pneumoniae was strongly correlated with severe disease. S. pneumoniae was present in 56.4% of severe cases versus 25% of mild cases; more than one-third of H1N1pdm NPS with S. pneumoniae were from subjects with severe disease (22 of 62 S. pneumoniae-positive NPS, p = 0.0004). In subjects 6 to 55 years of age, the adjusted odds ratio (OR) of severe disease in the presence of S. pneumoniae was 125.5 (95% confidence interval [CI], 16.95, 928.72; p<0.0001).

Conclusions/Significance

The association of S. pneumoniae with morbidity and mortality is established in the current and previous influenza pandemics. However, this study is the first to demonstrate the prognostic significance of non-invasive antemortem diagnosis of S. pneumoniae infection and may provide insights into clinical management.

[Association between hand-foot-and-mouth disease in Xi'an and enterovirus 71]

OBJECTIVE

To isolate the prevalent strain of enterovirus 71 (EV71) in Xi'an area in 2008, and compare the concordance of viral isolation, reverse transcription polymerase chain reaction (RT-PCR) and immunofluorescent technique in detecting EV71, find the fast and effective method for detection, and analyze the differences between the EV71 strains isolated from Xi'an and Fuyang, Anhui.

METHOD

Virus isolation and RT-PCR were carried out on vesicle fluid and throat swab specimens that were collected from the patients with hand-foot-and-mouth disease, RD and HEp-2 cell lines were used for viral isolation. The virus was identified by using immunofluorescence technique. Nucleotide sequencing was performed on positive product of RT-PCR, and compared with EV71 isolated from Fuyang in 2008, then submitted to Genbank.

RESULT

Among the 56 samples of throat swab inoculated on RD and HEp-2 cells, the positive rates were 5.4% (3/56) and 1.8% (1/56), respectively. Among the 56 samples of vesicle fluid inoculated on RD and HEp-2 cells, the positive rates were 12.5% ( 7/56 ) and 5.4% (3/56), respectively. Cytopathic effect of RD and HEp-2 cells appeared on days 7 and 10, respectively. The positive rates of RT-PCR on throat swab and vesicle fluid samples were 21.4% (12/56) and 33.9% (19/56), respectively. Cytopathic effect was found in cell culture for 14 cases and immunofluorescence, showed that 9 of them were infected with EV71. The authors obtained the EV71 strain prevalent in Xi'an during 2008. The nucleotide sequence was submitted to the NCBI Genbank and gained the accession number EU812461.

CONCLUSION

The EV71 in Xi'an prevalent during 2008 may have a weaker epithelial tropism. Comparison of the EV71 strain isolated from Xi'an with EU703812, EU703813 and EU703814 isolated from Fuyang, Anhui showed that the homology was 97%-98%. RT-PCR is an important method for rapid detection of EV71.

Usefulness of Herpes Consensus PCR methodology to routine diagnostic testing for herpesviruses infections in clinical specimens

The purposes of the study were to assess the usefulness of simultaneously amplifying herpes simplex virus 1 and 2, varicella-zoster virus, cytomegalovirus, Epstein-Barr virus and human herpesvirus 6 DNA in various clinical specimens and to analyze clinical events in patients presenting positive results. A total of 763 clinical samples obtained from 758 patients, including 115 cerebrospinal fluids, 102 aqueous fluids, 445 swabs from genital (152), oro-facial (138) and other (155) skin lesions, 96 eye swabs and 5 bronchoalveolar lavages, were tested by using the Consensus polymerase chain reaction methodology. The clinical files of the patients were consulted retrospectively. 171 of the 758 patients (22.5%) were positive for at least one of the six target viruses: herpes simplex virus 1 (n = 95), varicella-zoster virus (n = 40), herpes simplex virus 2 (n = 21), herpes simplex virus 1 plus herpes simplex virus 2 (n = 8), cytomegalovirus (n = 4), Epstein-Barr virus (n = 1), human herpesvirus 6 (n = 1), and herpes simplex virus 1 plus human herpesvirus 6 (n = 1). The Consensus methodology enabled the rapid and accurate detection of herpesviruses in various clinical specimens and provided a reliable tool in the diagnosis of herpetic infections.

Intratracheal inoculation of severe acute respiratory syndrome coronavirus in monkeys Macaca rhesus

An animal model for infection with Severe acute respiratory syndrome coronavirus (SARSCoV) was evaluated in monkeys Macaca rhesus. The monkeys were inoculated into the trachea with NS-I strain of SARS-CoV and the clinical manifestation of the illness was monitored. The clinical samples collected from infected monkeys were examined by immumnofluorescence assay (IFA), pathological inspection, RTPCR, and by virus isolation. The infected animals demonstrated mild clinical symptoms including fever. Two of the six infected monkeys developed fever (1.5 above the level before challenge) on the day 10 post inoculation (p.i.). Although the severe clinical symptoms or mortality were not observed, the virological and histopathological evidences of the illness were evident. The specimens collected from the infected animals showed the presence of SARS-CoV detected by RT-PCR, IFA, and by virus isolation. From the organs examined postmortem, a major pathological change was observed in the lungs. The walls of the alveoli were thicker, infiltrated with inflammation cells and an exudative fluid was found in the alveolar spaces. In addition, some alveolar spaces showed hyaline membrane lining. The results showed that the monkeys infected with SARS-CoV developed the typical SARS according to clinical, virological, and pathological findings.

High levels of hepatitis B virus DNA in body fluids from chronic carriers

Chronic infection with hepatitis B virus (HBV) is a major global health problem. Transmission is mainly blood-borne, although the route of infection during horizontal transmission in childhood is unclear. Nosocomial outbreaks of HBV have been widely reported, but have mainly focused on blood-borne transmission. There is limited knowledge of the viral load levels in other body fluids. In the present study, chronic HBV carriers were tested for the presence of HBV DNA in serum, saliva, nasopharyngeal fluid, urine and tears by means of qualitative and quantitative polymerase chain reaction (PCR) methods. Twenty-five patients who were positive for HBV DNA with both PCRs were included. Low titres in real-time PCR corresponded with weak bands in the qualitative assay. HBV DNA was found in two urine samples, 10 saliva samples, five nasopharyngeal swabs and in tear fluid from four patients. One highly viraemic HBeAg-positive carrier with serum HBV DNA levels of 7 x 10(9) genome copies had high copy numbers detected in both saliva and nasopharyngeal fluid. These results demonstrate that highly viraemic HBV carriers may have high titres of HBV DNA in other body fluids. This has particular importance for infection control programmes and regulations, underlining the importance of aiming towards regular HBV DNA testing and thus infectivity assessment of chronic carriers in order to prevent transmission.

JC virus detection in bodily fluids: clues to transmission

JC virus in saliva, oropharyngeal fluid, blood, and urine samples obtained from 58 human immunodeficiency virus-infected persons and 58 matched controls was investigated by performing quantitative polymerase chain reaction. JC virus was rarely present in oropharyngeal fluid and blood samples, even in those obtained from immunosuppressed individuals, but it was commonly detected in urine samples from both groups, suggesting that urine contributes to transmission.

The relationship of rhinovirus-associated asthma hospitalizations with inhaled corticosteroids and smoking

BackgroundAlthough rhinovirus (RV) respiratory infections trigger asthma exacerbations, the etiologic association between this virus and severe exacerbations, as well as the clinical characteristics of adults at risk for RV-associated asthma that necessitates hospitalization, have not been established

MethodsDuring 1999–2003, we conducted a cohort study of 101 adults prospectively enrolled at hospital admission for an asthma exacerbation. Patient characteristics and frequencies of RV in nasal specimens were analyzed, by reverse-transcription polymerase chain reaction (RT-PCR), at asthma-related hospital admission and at a 3-month convalescent follow-up visit

ResultsRV was detected by RT-PCR in 21% of hospitalized patients over a 4-year period and in 1.3% of patients who returned for a 3-month follow-up visit. RV detection was strongly associated with hospitalization for asthma (adjusted odds ratio [OR], 15.1 [95% confidence interval {CI}, 1.88–121.4]). After adjustment for baseline asthma severity, RV-positive patients were more likely than RV-negative patients to be current smokers and nonusers of inhaled corticosteroids (ICSs) (adjusted OR, 11.18 [95% CI, 2.37–52.81]; P=.002)

ConclusionsRV respiratory infection is an etiologic agent in severe asthma exacerbations necessitating hospitalization in adults. Compared with hospitalized patients with asthma who were RV negative, RV-positive patients were significantly more likely to be smokers and nonusers of ICSs

Hepatitis B surface antigen (HbsAg) in blood and genital secretions of patients with sexually transmitted diseases in Ibadan, Nigeria

A total of 100 patients attending the Special Treatment Clinic of the University Teaching Hospital (UCH), Ibadan between October, 1998 and April, 1999 were studied to detect Hepatitis B surface antigen (HbsAg) in the blood and genital discharges. This was with a view of establishing whether infected persons (positive by blood test) also excrete the antigen, HbsAg, in their genital secretions. Urethral swabs were collected from 63 male patients, while High Vaginal and Endocervical swabs were collected from 37 female patients. Blood samples were collected from all the patients. HbsAg was tested for by Enzyme immunoassay technique with Wellcozyme HbsAg kit. Of the 63 male patients, 10 (15.9%) had HbsAg in the urethral secretion while 22 (34.9%) had it in their blood, 70% of these male patients were within the age range 11-30 years. Of the 37 female patients, 34 (92%) had HbsAg in the Endocervical secretions, 6 (16.2%) of them had HbsAg in their blood. Eighty percent of the female patients with positive HbsAg in the genital secretions were within age range 21-40 years. This study documents that Hepatitis B virus can be transmitted sexually in this environment.

Detection, quantification and genotyping of Herpes Simplex Virus in cervicovaginal secretions by real-time PCR: a cross sectional survey

Background

Herpes Simplex Virus (HSV) Genital Ulcer Disease (GUD) is an important public health problem, whose interaction with HIV results in mutually enhancing epidemics. Conventional methods for detecting HSV tend to be slow and insensitive. We designed a rapid PCR-based assay to quantify and type HSV in cervicovaginal lavage (CVL) fluid of subjects attending a Genito-Urinary Medicine (GUM) clinic. Vaginal swabs, CVL fluid and venous blood were collected. Quantitative detection of HSV was conducted using real time PCR with HSV specific primers and SYBR Green I. Fluorogenic TaqMan Minor Groove Binder (MGB) probes designed around a single base mismatch in the HSV DNA polymerase I gene were used to type HSV in a separate reaction. The Kalon test was used to detect anti-HSV-2 IgG antibodies in serum. Testing for HIV, other Sexually Transmitted Infections (STI) and related infections was based on standard clinical and laboratory methods.

Results

Seventy consecutive GUM clinic attendees were studied. Twenty-seven subjects (39%) had detectable HSV DNA in CVL fluid; HSV-2 alone was detected in 19 (70%) subjects, HSV-1 alone was detected in 4 (15%) subjects and both HSV types were detected in 4 (15%) subjects. Eleven out of 27 subjects (41%) with anti-HSV-2 IgG had detectable HSV-2 DNA in CVL fluid. Seven subjects (10%) were HIV-positive. Three of seven (43%) HIV-infected subjects and two of five subjects with GUD (40%) were secreting HSV-2. None of the subjects in whom HSV-1 was detected had GUD.

Conclusion

Quantitative real-time PCR and Taqman MGB probes specific for HSV-1 or -2 were used to develop an assay for quantification and typing of HSV. The majority of subjects in which HSV was detected had low levels of CVL fluid HSV, with no detectable HSV-2 antibodies and were asymptomatic.

[Determination of SARS-CoV by simplified nested fluorescent RT-PCR]

OBJECTIVE

To establish a simple rapid and sensitive nested RT-PCR method for detection of SARS coronavirus RNA by designing the specific primers for SARS and optimizing the parameters for PCR.

METHODS

Primers and fluorescent probes were designed according to the sequences of SARS coronavirus genes available from GenBank. The optimization of the parameters for PCR was performed in PE 7700 thermal cycle. The 36 serum samples and 40 mouthwash of SARS patients and 80 samples of healthy people were tested.

RESULTS

The positive rate of patient serum and mouthwash was 33.6%, (12/36) and 67.5%, (27/40), respectively, while the positive rate of healthy people was zero (0/160).

CONCLUSION

The simple nested RT-PCR method was a rapid, efficient and sensitive one for SARS early diagnosis.

The effect of vaginal candidiasis on the shedding of human immunodeficiency virus in cervicovaginal secretions

OBJECTIVE

The purpose of this study was to evaluate the influence of symptomatic vulvovaginal candidiasis on the shedding of HIV-1 in cervicovaginal secretions of HIV-1-infected women.

STUDY DESIGN

We obtained paired blood and cervicovaginal lavage samples from 66 HIV-infected women with symptomatic vulvovaginal candidiasis, and 249 HIV-infected control patients without genital infection. HIV-1 RNA in plasma, proviral HIV-1 DNA, HIV-1 RNA transcripts, and cell-free HIV-1 RNA in cervicovaginal secretions were quantitatively evaluated by competitive polymerase chain reaction (cPCR) and reverse transcriptase PCR (cRT-PCR). We used logistic regression on ordered data to assess the influence of vulvovaginal candidiasis on the HIV-1 load in cervicovaginal secretions adjusting for potential confounders.

RESULTS

Overall, the amount of HIV-1 RNA in plasma was significantly correlated with HIV-1 DNA (Spearman rank 0.153 +/- 0.059, P = .006), HIV-1 RNA transcripts (Spearman rank 0.169 +/- 0.058, P = .003), and cell free HIV-1 RNA (Spearman rank 0.185 +/- 0.059, P = .001) load in cervicovaginal secretion. Forty-eight out of 182 (26.4%) patients who tested negative for HIV-1 RNA in plasma were positive for HIV-DNA in their cervicovaginal secretions. In logistic regression analysis vulvovaginal candidiasis was significantly associated with increasing loads of HIV-1 RNA transcripts (Odds ratio [OR] 1.97, 95% CI 1.09-3.57, P = .025) and cell free HIV-1 RNA (OR 2.03, 95% CI 1.10-3.73, P = .02) in cervicovaginal secretions.

CONCLUSION

In HIV-infected women, vulvovaginal candidiasis is associated with an increased number of copies of cell-associated and cell-free HIV-1 RNA in cervicovaginal secretions.

Selection of a secretion-incompetent mutant in the serum of a patient with severe hepatitis B

BACKGROUND AND AIMS

A secretion-incompetent, highly replicating hepatitis B variant was previously found as the dominant viral population in the serum of a liver transplant recipient with severe hepatitis B reinfection. The secretion block resulted from mutations in the S protein, including the Gly145Arg substitution known to emerge under antibody to hepatitis B surface antigen immunoglobulin treatment. Here we investigated the mechanisms that allow selection of a secretion-incompetent virus as the predominant strain in the serum.

METHODS

To reproduce the interaction of viral quasispecies occurring in vivo, cotransfection experiments were performed with full-length genomes containing wild-type or mutant sequences. In addition, the relevance of mutations in the common S part of the surface proteins for the competence of L and S protein to support viral secretion was studied.

RESULTS

A small amount of wild-type virus or of a wild-type S protein-expressing variant rescued secretion of the defective mutant. In the secreted virions, the high-replicating mutant genome was predominant. Selection of the defective mutant was further supported by a transdominant negative effect of mutant S protein on wild-type virion secretion. In contrast, mutant L protein with the same c-terminal mutations as mutant S protein efficiently supported virion formation and secretion.

CONCLUSIONS

Interaction of the variant with a small amount of wild-type virus can reverse its secretion-defective phenotype. Mutations in the common region of S and L protein have different consequences for the ability of the envelope proteins to support virion assembly and secretion.

Exposure to HIV-1 during delivery and mother-to-child transmission

BACKGROUND

The correlation between the presence of HIV-1 in maternal cervicovaginal secretions and in the infant's oro-pharyngal secretions at birth, and mother-to-child HIV transmission (MTCT) were examined to obtain a better understanding of its mechanism.

METHODS

Women without medical and obstetrical complications, living within a reasonable distance of the government hospital in Mombasa, Kenya, were recruited after informed consent. Maternal and infant characteristics were collected. Polymerase chain reaction was used to detect HIV-1 in cervico-vaginal and oro-pharyngal secretions. Infants were tested for HIV-1 by polymerase chain reaction within 48 h and at 6 weeks after delivery.

RESULTS

Between April 1998 and April 1999, 228 woman-infant pairs were included in the study. HIV-1 DNA in cervico-vaginal secretions was independently associated with HIV-1 maternal viral load and with infant birth-weight, whereas HIV-1 RNA was associated with maternal viral load and maternal age. HIV-1 DNA in the oropharyngal secretions was also independently associated with maternal viral load. MTCT rate at the age of 6 weeks was 23.6%. Intrapartum and early postpartum HIV transmission was independently associated with maternal viral load [adjusted odds ratio (OR), 1.6; 95% confidence interval (CI),1.0-2.7], detection of HIV-1 RNA in cervico-vaginal secretions (adjusted OR, 3.2; 95% CI, 1.5-7.3) and of HIV-1 DNA in oro-pharyngeal secretions (adjusted OR, 3.2; 95% CI, 1.1-9.0).

DISCUSSION

As far as is known, this is the first study showing that infant exposure to HIV-1 in the birth canal and the presence of HIV-infected cells in the infant's oropharyngeal cavity are independently associated with intrapartum and early postpartum MTCT. It supports the hypothesis that MTCT could occur through the oral route.