Fecal Virus Shedding Research Articles

The impact of the COVID-19 pandemic on Clostridioides difficile infection and utilization of fecal microbiota transplantation

Previous research has demonstrated that the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) gains cell entry through the angiotensin-converting enzyme 2 receptor, which is abundantly found throughout the gastrointestinal (GI) tract, resulting in a wide array of GI manifestations of coronavirus disease 2019 (COVID-19). By gaining entry into the intestinal epithelial and stromal cells, SARS-CoV-2 has been observed to cause intestinal inflammation and gut dysbiosis. Alterations in gut microbiota are known to be involved in the pathophysiology of Clostridioides difficile infection (CDI). During the initial stages of the COVID-19 pandemic, rates of CDI were similar to historical data despite the increased use of antibiotics. This may be due to increased emphasis on hygiene and protective equipment and reduced C. difficile testing as diarrhea was presumed to be COVID-19 related. Studies also demonstrated additional risk factors for CDI in COVID-19 patients, including length of hospitalization and new abdominal pain during admission. Although not associated with increased mortality, CDI was associated with increased length of hospital stay among patients admitted with COVID-19. Due to fecal viral shedding and concern of oral-fecal transmission of SARS-CoV-2, increased safety regulations were introduced to fecal microbiota transplantation (FMT) leading to reduced rates of this procedure during the COVID-19 pandemic. FMT for recurrent CDI during the COVID-19 pandemic remained highly effective without any reports of SARS-CoV-2 transmission. In addition, limited data show that FMT may be effective in treating COVID-19 and restoring healthy gut microbiota. The goal of this article is to review the impact that the COVID-19 pandemic has had on hospital-acquired CDI and the utilization of FMT.

Therapeutic efficacy of n-Docosanol against velogenic Newcastle disease virus infection in domestic chickens.

The control of Newcastle disease virus (NDV) infection depends solely on vaccination which in most cases is not sufficient to restrain the consequences of such a highly evolving viral disease. Finding out substances for preparing an efficient anti-ND drug would be of high value. n-Docosanol is a saturated fatty alcohol with an inhibitory effect against many enveloped viruses. In this study, we evaluated the therapeutic effect of n-docosanol on NDV infection and shedding in chickens. Chickens infected with a highly virulent NDV were treated with low to high concentrations of n-docosanol (20, 40, and 60 mg/kg body weight) for 4-successive days, once they showed the disease symptoms. Survival and curative rates, virus load, histopathological scoring, and virus shedding were defined. Symptoms development was found to discontinue 24-72 hours post-treatment. Survival rate in the NDV-infected chickens raised 37.4-53.2% after the treatment. n-Docosanol treatment was also found to significantly reduce virus load in the digestive (26.2-33.9%), respiratory (38.3-63%), nervous (26.7-51.1%), and lymphatic (16.4-29.1%) tissues. Histopathological scoring of NDV lesions revealed prominent rescue effects on the histology of different tissues. Importantly, n-docosanol treatment significantly reduced virus shedding in oropharyngeal discharge and feces thereby allowing the restriction of NDV spread. Our findings suggest n-docosanol as a promising remedy in the control strategy of Newcastle disease in the poultry industry.

Macrophage Depletion Reactivates Fecal Virus Shedding following Resolution of Acute Hepatitis A in Ifnar1-/- Mice.

Although hepatitis A virus (HAV) is associated only with acute hepatitis in humans, HAV RNA persists within the liver for months following resolution of liver inflammation and cessation of fecal virus shedding in chimpanzees and murine models of hepatitis A. Here, we confirm striking differences in the kinetics of HAV RNA clearance from liver versus serum and feces in infected Ifnar1-/- mice and investigate the nature of viral RNA persisting in the liver following normalization of serum alanine aminotransferase (ALT) levels. Fecal shedding of virus produced in hepatocytes declined >3,000-fold between its peak at day 14 and day 126, whereas intrahepatic HAV RNA declined only 32-fold by day 154. Viral RNA was identified within hepatocytes 3 to 4 months after inoculation and was associated with membranes, banding between 1.07 and 1.14 g/cm3 in isopycnic iodixanol gradients. Gradient fractions containing HAV RNA demonstrated no infectivity when inoculated into naive mice but contained neutralizing anti-HAV antibody. Depleting CD4+ or CD8+ T cells at this late point in infection had no effect on viral RNA abundance in the liver, whereas clodronate-liposome depletion of macrophages between days 110 and 120 postinoculation resulted in a striking recrudescence of fecal virus shedding and the reappearance of viral RNA in serum coupled with reductions in intra-hepatic Ifnγ, Tnfα, Ccl5, and other chemokine transcripts. Our data suggest that replication-competent HAV RNA persists for months within the liver in the presence of neutralizing antibody following resolution of acute hepatitis in Ifnar1-/- mice and that macrophages play a key role in viral control late in infection. IMPORTANCE HAV RNA persists in the liver of infected chimpanzees and interferon receptor-deficient Ifnar1-/- mice for many months after neutralizing antibodies appear, virus has been cleared from the blood, and fecal virus shedding has terminated. Here, we show this viral RNA is located within hepatocytes and that the depletion of macrophages months after the resolution of hepatic inflammation restores fecal virus shedding and circulating viral RNA. Our study identifies an important role for macrophages in virus control following resolution of acute hepatitis A in Ifnar1-/- mice and may have relevance to relapsing hepatitis A in humans.

Prolonged viral shedding in feces of children with COVID-19: a systematic review and synthesis of data

During the coronavirus disease 2019 (COVID-19) epidemic, many reports have indicated that children shed the virus longer than adults in stool, and that most of the children had mild or even asymptomatic infections, which increased the potential risk for feces to be a source of contamination and may play an important role in the spread of the virus. In this review, we collected relevant literature to summarize the duration of fecal viral shedding in children with COVID-19. We found that in about 60% of the cases, the fecal shedding time was between 28 and 42 days, which was much longer than that of adults. We further explored the possible reason for prolonged shedding and its the potential impact. The poor hand hygiene practices of children, their tendency to swallow sputum and/or saliva, the significant difference in expression of angiotensin-converting enzyme 2 (ACE2) in intestine between children and adults, and the variance in immune status and intestinal microbiome could be considered as potential casual agents of longer fecal viral shedding duration of children. Conclusion: Children with COVID-19 show prolonged fecal shedding compared to adults. Several mechanisms may be involved in the longer fecal viral shedding. Viral shedding in the stool could be contributing to a possible route of transmission. Therefore, we think that further preventive measures in children should be taken to reduce the spread of the disease. What is Known:• Children with COVID-19 are more likely to have asymptomatic infections and to experience mild symptoms.• Some patients continue to shed the virus in feces, despite respiratory samples testing negative.What is New:• Children with COVID-19 carried a longer-term fecal viral shedding than adults.• The poor hand hygiene practices of children, their tendency to swallow sputum and/or saliva, the difference in expression of ACE2 in intestine between children and adults, and the variance in immune status and intestinal microbiome could be considered as potential casual agents of longer fecal viral shedding duration of children.

The infectivity and pathogenicity of hepatitis A virus live-attenuated vaccine strain H2 in type I interferon receptor-deficient mice.

Hepatitis A virus (HAV) live-attenuated vaccine H2 strain has been approved for clinical use for decades with ideal safety profiles in nonhuman primate models and humans. Recently, type I interferon (IFN) receptor-deficient mice were shown to be susceptible to HAV infection. Herein, we sought to determine the infection and replication dynamics of the H2 in Ifnar−/− mice that lack type I IFN receptor. Following intravenous injection, the H2 failed to cause obvious clinical symptoms in Ifnar−/− mice, and no significant upregulation in serum alanine aminotransferase (ALT) levels was observed. Notably, the histopathological examination showed that there were significant focal infiltrations of lymphocytes and neutrophils in the portal area, but no focal necrosis was observed in liver tissues. Viral RNAs sustained in the liver, and the infectious virus could be recovered from the liver tissue until 42 days post-infection. More importantly, H2 infection induced obvious viremia and persistent viral shedding in feces. In addition, robust HAV-specific humoral immune responses were induced in Ifnar−/− mice. Overall, our study revealed the safety profile of H2 in Ifnar−/− mice, which not only helps understand the attenuation mechanism of H2, but also expands the application of the Ifnar−/− mouse model for HAV studies.

Immunization with Virus-Like Particle Vaccine Protects Rabbits against Hepatitis E-3 Virus Infection.

Here, rabbits were immunized with a virus-like particle (VLP) vaccine prepared by expressing 239 amino acids of the swine hepatitis E virus (HEV)-3 capsid protein using a baculovirus system. Thirty specific-pathogen-free rabbits were divided into five groups (negative and positive control and 10, 50, and 100 μg VLP-vaccinated). Positive control group rabbits showed viremia and fecal viral shedding, whereas rabbits vaccinated with 10 μg VLP showed transient fecal viral shedding, and rabbits vaccinated with 50 and 100 μg VLP did not show viremia or fecal viral shedding. Serum anti-HEV antibody titers increased in a dose-dependent manner. Anti-HEV antibody titers were significantly higher (p < 0.05) in 100 μg VLP-vaccinated rabbits than in the negative control rabbits at week 4. Anti-HEV antibody titers were significantly higher in 50 and 10 μg VLP-vaccinated rabbits than in the negative control rabbits at weeks 8 and 11, respectively. Serum IFN-γ and IL-12 levels were significantly higher (p < 0.01) in rabbits vaccinated with 50 and 100 μg VLP than in the negative control rabbits at weeks 4 and 6. Liver tissues of 50 and 100 μg VLP-vaccinated rabbits displayed significantly less (p < 0.05) fibrosis than those of the positive control rabbits. The prepared VLP vaccine demonstrated dose-dependent immunogenicity sufficient for inducing anti-HEV antibody production, thus protecting rabbits against swine HEV-3.

Identification of Pulmonary Infections With Porcine Rotavirus A in Pigs With Respiratory Disease.

While rotavirus (RV) is primarily known to cause gastroenteritis in many animals, several epidemiological studies have shown concurrent respiratory symptoms with fecal and nasal virus shedding. However, respiratory RV infections have rarely been investigated. By screening clinical samples submitted for diagnostic testing, porcine rotavirus A (RVA) was detected by quantitative reverse transcription PCR (qRT-PCR) in 28 out of 91 (30.8%) lungs obtained from conventionally reared pigs with respiratory signs. Among the positive cases, intensive RVA signals were mainly localized in alveolar macrophages (n = 3) and bronchiolar epithelial cells (n = 1) by RNAscope® in situ hybridization (ISH). The signals of RVA in bronchiolar epithelial cells were verified by ISH with different probes, immunohistochemistry, and transmission electron microscopy. Furthermore, additional cases with RVA ISH-positive signals in alveolar macrophages (n = 9) and bronchial epithelial cells (n = 1) were identified by screening 120 archived formalin-fixed and paraffin-embedded lung samples using tissue microarrays. Overall, our study showed a high frequency of RVA detection in lungs from conventional pigs with respiratory disease. Further research is needed to determine if RVA infection in the respiratory epithelium correlates with nasal shedding of rotavirus and its contribution to respiratory disease.

Fecal Feline Coronavirus RNA Shedding and Spike Gene Mutations in Cats with Feline Infectious Peritonitis Treated with GS-441524.

As previously demonstrated by our research group, the oral multicomponent drug Xraphconn® containing GS-441524 was effective at curing otherwise fatal feline infectious peritonitis (FIP) in 18 feline coronavirus (FCoV)-infected cats. The aims of the current study were to investigate, using samples from the same animals as in the previous study, (1) the effect of treatment on fecal viral RNA shedding; (2) the presence of spike gene mutations in different body compartments of these cats; and (3) viral RNA shedding, presence of spike gene mutations, and anti-FCoV antibody titers in samples of 12 companion cats cohabitating with the treated cats. Eleven of the eighteen treated FIP cats (61%) were shedding FCoV RNA in feces within the first three days after treatment initiation, but all of them tested negative by day 6. In one of these cats, fecal shedding reoccurred on day 83. Two cats initially negative in feces were transiently positive 1–4 weeks into the study. The remaining five cats never shed FCoV. Viral RNA loads in feces decreased with time comparable with those in blood and effusion. Specific spike gene mutations linked to systemic FCoV spread were consistently found in blood and effusion from treated FIP cats, but not in feces from treated or companion cats. A new mutation that led to a not yet described amino acid change was identified, indicating that further mutations may be involved in the development of FIP. Eight of the twelve companion cats shed FCoV in feces. All but one of the twelve companion cats had anti-FCoV antibodies. Oral treatment with GS-441524 effectively decreased viral RNA loads in feces, blood, and effusion in cats with FIP. Nonetheless, re-shedding can most likely occur if cats are re-exposed to FCoV by their companion cats.

Gastrointestinal symptoms and fecal shedding of SARS-CoV-2 RNA suggest prolonged gastrointestinal infection

BackgroundCOVID-19 manifests with respiratory, systemic, and gastrointestinal (GI) symptoms.1, SARS-CoV-2 RNA is detected in respiratory and fecal samples, and recent reports demonstrate viral replication in both the lung and intestinal tissue.2, 3, 4 Although much is known about early fecal RNA shedding, little is known about long-term shedding, especially in those with mild COVID-19. Furthermore, most reports of fecal RNA shedding do not correlate these findings with GI symptoms.5MethodsWe analyzed the dynamics of fecal RNA shedding up to 10 months after COVID-19 diagnosis in 113 individuals with mild to moderate disease. We also correlated shedding with disease symptoms.FindingsFecal SARS-CoV-2 RNA is detected in 49.2% [95% confidence interval, 38.2%–60.3%] of participants within the first week after diagnosis. Whereas there was no ongoing oropharyngeal SARS-CoV-2 RNA shedding in subjects at 4 months, 12.7% [8.5%–18.4%] of participants continued to shed SARS-CoV-2 RNA in the feces at 4 months after diagnosis and 3.8% [2.0%–7.3%] shed at 7 months. Finally, we found that GI symptoms (abdominal pain, nausea, vomiting) are associated with fecal shedding of SARS-CoV-2 RNA.ConclusionsThe extended presence of viral RNA in feces, but not in respiratory samples, along with the association of fecal viral RNA shedding with GI symptoms suggest that SARS-CoV-2 infects the GI tract and that this infection can be prolonged in a subset of individuals with COVID-19.FundingThis research was supported by a Stanford ChemH-IMA grant; fellowships from the AACR and NSF; and NIH R01-AI148623, R01-AI143757, and UL1TR003142.

Characteristics of COVID-19 Patients With SARS-CoV-2 Positivity in Feces.

BackgroundSARS-CoV-2 is highly contagious and poses a great threat to epidemic control and prevention. The possibility of fecal-oral transmission has attracted increasing concern. However, viral shedding in feces has not been completely investigated.MethodsThis study retrospectively reviewed 97 confirmed coronavirus disease 2019 (COVID-19) patients hospitalized at the First Affiliated Hospital, School of Medicine, Zhejiang University, from January 19 to February 17, 2020. SARS-CoV-2 RNA in samples of sputum, nasopharyngeal or throat swabs, bronchoalveolar lavage and feces was detected by real-time reverse transcription polymerase chain reaction (RT–PCR). Clinical characteristics and parameters were compared between groups to determine whether fecal RNA was positive.ResultsThirty-four (35.1%) of the patients showed detectable SARS-CoV-2 RNA in feces, and 63 (64.9%) had negative detection results. The median time of viral shedding in feces was approximately 25 days, with the maximum time reaching 33 days. Prolonged fecal-shedding patients showed longer hospital stays. Those patients for whom fecal viral positivity persisted longer than 3 weeks also had lower plasma B-cell counts than those patients in the non-prolonged group [70.5 (47.3-121.5) per μL vs. 186.5 (129.3-376.0) per μL, P = 0.023]. Correlation analysis found that the duration of fecal shedding was positively related to the duration of respiratory viral shedding (R = 0.70, P < 0.001) and negatively related to peripheral B-cell counts (R = -0.44, P < 0.05).ConclusionsCOVID-19 patients who shed SARS-CoV-2 RNA in feces presented similar clinical characteristics and outcomes as those who did not shed SARS-CoV-2 RNA in feces. The prolonged presence of SARS-CoV-2 nucleic acids in feces was highly correlated with the prolonged shedding of SARS-CoV-2 RNA in the respiratory tract and with lower plasma B-cell counts.

Intradermal fractional-dose inactivated polio vaccine (fIPV) adjuvanted with double mutant Enterotoxigenic Escherichia coli heat labile toxin (dmLT) is well-tolerated and augments a systemic immune response to all three poliovirus serotypes in a randomized placebo-controlled trial

Eradication of poliomyelitis globally is constrained by fecal shedding of live polioviruses, both wild-type and vaccine-derived strains, into the environment. Although inactivated polio vaccines (IPV) effectively protect the recipient from clinical poliomyelitis, fecal shedding of live virus still occurs following infection with either wildtype or vaccine-derived strains of poliovirus. In the drive to eliminate the last cases of polio globally, improvements in both oral polio vaccines (OPV) (to prevent reversion to virulence) and injectable polio vaccines (to improve mucosal immunity and prevent viral shedding) are underway. The E. coli labile toxin with two or “double” attenuating mutations (dmLT) may boost immunologic responses to IPV, including at mucosal sites. We performed a double-blinded phase I controlled clinical trial to evaluate safety, tolerability, as well as systemic and mucosal immunogenicity of IPV adjuvanted with dmLT, given as a fractional (1/5th) dose intradermally (fIPV-dmLT). Twenty-nine volunteers with no past exposure to OPV were randomized to a single dose of fIPV-dmLT or fIPV alone. fIPV-dmLT was well tolerated, although three subjects had mild but persistent induration and hyperpigmentation at the injection site. A ≥ 4-fold rise in serotype-specific neutralizing antibody (SNA) titers to all three serotypes was seen in 84% of subjects receiving fIPV-dmLT vs. 50% of volunteers receiving IPV alone. SNA titers were higher in the dmLT-adjuvanted group, but only differences in serotype 1 were significant. Mucosal immune responses, as measured by polio serotype specific fecal IgA were minimal in both groups and differences were not seen. fIPV-dmLT may offer a benefit over IPV alone. Beyond NAB responses protecting the individual, studies demonstrating the ability of fIPV-dmLT to prevent viral shedding are necessary. Studies employing controlled human infection models, using monovalent OPV post-vaccine are ongoing. Studies specifically in children may also be necessary and additional biomarkers of mucosal immune responses in this population are needed.Clinicaltrials.gov Identifer: NCT03922061.

Identification and pathogenicity of hepatitis E Virus from laboratory Bama miniature pigs

BackgroundHepatitis E virus (HEV) genotypes 3 and 4 are zoonotic. In this study, HEV infection in laboratory Bama miniature pigs in Sichuan Province of China was investigated. Firstly, one hundred rectal swabs were collected for HEV RNA testing, and chose positive samples for sequence analysis. Concurrently, for pathogenicity study, six healthy Bama miniature pigs were randomly divided into two groups of 3 pigs each. A total of 500 μL of HEV stock (positive fecal samples identified in this study) was inoculated intravenously into each pig in the experimental group, and the three pigs in the other group served as negative controls. Serum and fecal samples were collected at 1 to 10 weeks post-inoculation (wpi) for alanine aminotransferase (ALT) levels, anti-HEV antibodies and HEV RNA detection, respectively. During necropsies, liver lesions and HEV antigen in liver were observed at 10 wpi.ResultsThe rate of fecal sample HEV RNA-positivity was 12% (12/100). Sequence comparisons indicated that partial ORF1 and ORF2 gene sequences of this isolate shared highest identities with corresponding sequences of genotype 4a HEV isolates (81.4%-96.1% and 89.9%-97.1%, respectively). Phylogenetic tree analysis further demonstrated that sequences of this isolate clustered together with sub-genotype 4a HEV isolate sequences. Experimentally, the pathogenicity of Bama miniature pigs infected with this isolate exhibited viremia, fecal virus shedding, seroconversion, ALT level increasing, liver lesions and HEV antigen in liver.ConclusionsThis is the first study to confirm that HEV is currently circulating in laboratory Bama miniature pigs in China and this isolate can successfully infect Bama miniature pigs experimentally. More importantly, this study suggested HEV screening of laboratory pigs should be conducted to prevent research personnel from acquiring zoonotic HEV infections.

A Triple Gene-Deleted Pseudorabies Virus-Vectored Subunit PCV2b and CSFV Vaccine Protects Pigs against PCV2b Challenge and Induces Serum Neutralizing Antibody Response against CSFV.

Porcine circovirus type 2 (PCV2) is endemic worldwide. PCV2 causes immunosuppressive infection. Co-infection of pigs with other swine viruses, such as pseudorabies virus (PRV) and classical swine fever virus (CSFV), have fatal outcomes, causing the swine industry significant economic losses in many if not all pig-producing countries. Currently available inactivated/modified-live/vectored vaccines against PCV2/CSFV/PRV have safety and efficacy limitations. To address these shortcomings, we have constructed a triple gene (thymidine kinase, glycoprotein E [gE], and gG)-deleted (PRVtmv) vaccine vector expressing chimeric PCV2b-capsid, CSFV-E2, and chimeric Erns-fused with bovine granulocytic monocyte-colony stimulating factor (Erns-GM-CSF), designated as PRVtmv+, a trivalent vaccine. Here we compared this vaccine’s immunogenicity and protective efficacy in pigs against wild-type PCV2b challenge with that of the inactivated Zoetis Fostera Gold PCV commercial vaccine. The live PRVtmv+ prototype trivalent subunit vaccine is safe and highly attenuated in pigs. Based on PCV2b-specific neutralizing antibody titers, viremia, viral load in lymphoid tissues, fecal-virus shedding, and leukocyte/lymphocyte count, the PRVtmv+ yielded better protection for vaccinated pigs than the commercial vaccine after the PCV2b challenge. Additionally, the PRVtmv+ vaccinated pigs generated low to moderate levels of CSFV-specific neutralizing antibodies.

Feline panleukopenia virus DNA shedding following modified live virus vaccination in a shelter setting

This study assessed the frequency and timing of feline panleukopenia virus (FPV) shedding in feces following administration of a modified live FPV vaccine. Feces were collected from 37 shelter cats that did not meet clinical criteria for panleukopenia on the day of vaccination or on days 3, 7, 14, and 21 post-vaccination (NCL group). A commercial quantitative PCR (qPCR) fecal pathogen panel and a canine parvovirus point-of-care antigen test were performed. FPV DNA copy numbers from a concurrent study of 39 cats with panleukopenia (CL group) were compared with the NCL group.Of the 165 samples from the NCL group, one had a weak positive antigen test result on day 7, while nine samples (5.5%) from eight cats (21.6%) produced positive FPV qPCR test results, one on day 3 and eight on day 7. There were no day 21-positive qPCR results in the 11 cats that were revaccinated on day 14. There was no association between the number of additional fecal pathogens identified and a positive FPV qPCR result. Of the cats with positive results, FPV DNA copy numbers differed between NCL group and CL group (median 1.13 × 107 and 5.01 × 10⁸ copies/g feces, respectively; P < 0.001). The FPV qPCR cannot differentiate subclinical infection from vaccine virus shedding. To avoid unnecessary isolation and euthanasia, shelters should therefore limit FPV PCR testing to cats with a high index of suspicion of panleukopenia. The timing of recent vaccination should also be considered when interpreting test results.

Pigs Immunized with the Virus-like Particle Vaccine Are Protected against the Hepatitis E-3 Virus.

In this study, we generated the HEV virus-like particle (VLP) vaccine expressing 239 amino acids (367–605 aa) of the HEV-3 ORF2 using the baculovirus expression system. The HEV-3-239-VLP vaccine efficacy was evaluated by dividing 12 pathogen-free pigs into four groups: negative control, positive control, 100 μg VLP-, and 200 μg VLP-vaccinated groups for 10 weeks. The pigs in either of the vaccinated groups were administered the corresponding first and booster doses on weeks 0 and 2. At week 4, the positive control and two vaccinated groups were challenged with 106 HEV-3 genomic equivalent copies; viremia and fecal shedding of the virus were identified in pigs in the positive control and 100 μg VLP-vaccinated pigs showed transient viremia and fecal viral shedding. However, no viruses were detected in the serum or fecal samples of the 200 μg VLP-vaccinated pigs. The 100 and 200 μg VLP-vaccinated pigs had significantly higher (p < 0.01) anti-HEV antibodies than the negative control pigs from weeks 6–10 with normal levels of liver enzymes. The 200 μg VLP-vaccinated pigs showed statistically less liver tissue fibrosis (p < 0.05) than that of the positive control pigs. Thus, the novel baculovirus expression system-generated VLP vaccine dose-dependently protects against HEV-3 challenge and may be useful in other animal species, including humans.

Assessment of Fecal Viral Shedding Among Children Who Have COVID-19 by Polymerase Chain Reaction

Objective: This study aimed to assess fecal viral shedding in children who have been confirmed COVID-19 by real time polymerase chain reaction (RT-PCR). Material and Methods: We enrolled fifty inpatient children who have been confirmed COVID-19 during first wave of outbreak in our region. All of the patients have been twice confirmed by RT-PCR within nasopharyngeal swabs. Each case was evaluated with clinical data, laboratory tests and rectal swabs. The rectal swabs were obtained five days after nasopharyngeal positivity. The clinical data was recorded within two basic categories, including common symptoms or digestive symptoms. Detection of SARS-CoV-2 in rectal swabs was performed by RT-PCR method. Results: Fifteen patients (30%) had digestive symptoms. On the 5th day, 50 rectal swabs were studied with PCR-RT. Only one of them was positive (2%). The only patient who was positive for SARS-CoV-2 on rectal swab was a symptomatic threeand-a-half-year-old girl. The patient, who became asymptomatic in the follow-up, was retested with a nasopharyngeal swab one week later, the result was negative and she was discharged on the 10th day. The second rectal smear of the patient was negative. Conclusion: We found very low rate (2%) fecal viral shedding with rectal swab PCR among children who have been confirmed COVID-19 by nasopharyngeal swab PCR. We thought that this result was due to the mild clinical course of the patients who has been diagnosed with COVID-19 we followed up. However, fecal oral transmission might still matter in children.

Cellular and humoral immunity following vaccination with two different PCV2 vaccines (containing PCV2a or PCV2a/PCV2b) and challenge with virulent PCV2d

Porcine Circovirus type 2 (PCV2) associated disease is one of the most economically important swine diseases worldwide. Vaccines reduce PCV2 disease by inducing humoral immunity (neutralizing antibodies) and cell-mediated immunity (CMI) but may be improved by optimizing the immune response they induce. This study evaluated immune responses to a trivalent inactivated Porcine Circovirus (PCV) Type 1-Type 2a chimera (cPCV2a), cPCV2b and Mycoplasma hyopneumoniae (MH) (an experimental serial of Fostera® Gold PCV MH, also marketed as Circomax® Myco) vaccine or a bivalent recombinant PCV2a baculovirus expressed ORF2 capsid plus MH vaccine (Circumvent® PCV-M G2). Treatment Groups (T) received two doses of placebo (T01), one full or two split doses of the trivalent vaccine (T02, T03) or two split doses of the bivalent vaccine (T04) where two doses were given, there was a three-week period between administrations. All pigs were challenged with a virulent field isolate of PCV2d. CMI was measured as PCV2-specific IFN-γ secreting cells in blood and lymph node. Humoral immunity was measured as PCV2 antibodies. Vaccine efficacy was determined as viremia and fecal shedding of virus. There was a robust antibody response in T02 and T04 post the second vaccination and all vaccinated groups post challenge. There was a robust PCV2-specific IFN-γ response following the 1st dose in T02 and T03 and after the second dose in T02. T04 induced a low but detectable PCV2-specific IFN-γ response only after the 2nd dose. Among lymph node cells (study day 52), there was a significantly higher PCV2-specific, IFN-γ response to replicase and PCV2d capsid peptides in T01, consistent with active viral replication in non-vaccinated pigs. The trivalent chimeric vaccine induced robust CMI and protective efficacy, following a one dose regimen or splitting the dose into two vaccine administrations.

Molecular Biology and Pathological Process of an Infectious Bronchitis Virus with Enteric Tropism in Commercial Broilers.

Infectious bronchitis virus (IBV) induces respiratory and urogenital disease in chickens. Although IBV replicates in the gastrointestinal tract, enteric lesions are uncommon. We have reported a case of runting-stunting syndrome in commercial broilers from which an IBV variant was isolated from the intestines. The isolate, CalEnt, demonstrated an enteric tissue tropism in chicken embryos and SPF chickens experimentally. Here, we determined the full genome of CalEnt and compared it to other IBV strains, in addition to comparing the pathobiology of CalEnt and M41 in commercial broilers. Despite the high whole-genome identity to other IBV strains, CalEnt is rather unique in its nucleotide composition. The S gene phylogenetic analyses showed great similarity between CalEnt and Cal 99. Clinically, vent staining was slightly more frequent in CalEnt-infected birds than those challenged with M41. Furthermore, IBV IHC detection was more evident and the viral shedding in feces was overall higher with the CalEnt challenge compared with M41. Despite underlying intestinal lesions caused by coccidiosis and salmonellosis vaccination, microscopic lesions in CalEnt-infected chickens were more severe than in M41-infected chickens or controls, supporting the enteric tropism of CalEnt. Further studies in SPF chickens are needed to determine the pathogenesis of the virus, its molecular mechanisms for the enteric tropism, and its influence in intestinal health.

Genetic Characteristics and Pathogenicity of a Novel Porcine Deltacoronavirus Southeast Asia-Like Strain Found in China

Farmers involved in the lucrative pork trading business between China and Southeast Asian countries should be aware of a recently discovered novel porcine deltacoronavirus (PDCoV) in Guangxi province, China. A PDCoV strain, CHN/GX/1468B/2017, was isolated from the small intestinal contents of piglets with diarrhea from this region, with a titer of 1 × 108.0 TCID50/mL on LLC-PK cells. The full-length genome sequence consists of 25,399 nt as determined by next-generation sequencing and this was deposited in the GenBank (accession number MN025260.1). Genomic analysis showed that CHN/GX/1468B/2017 strain had 96.9~99.4% nucleotide homology with other 87 referenced PDCoV strains from different areas, and contained 6 and 9-nt deletions at positions 1,733~1,738 and 2,804~2,812, respectively, in the ORF1a gene. Phylogenetic analyses based on the whole gene sequence as well as S protein and ORF1a/1b protein sequences all showed that this strain was closely related to the Southeast Asia strain. When 7-day-old piglets were inoculated orally with the CHN/GX/1468B/2017 strain, they developed severe diarrhea, with a peak of fecal viral shedding at 4 days post-infection. Although no death or fever were observed, the CHN/GX/1468B/2017 strain produced a wide range of tissue tropism, with the main target being the intestine. Importantly, the VH:CD ratios of the jejunum and ileum in infected piglets were significantly lower than controls. These results indicate that CHN/GX/1468B/2017, isolated in China, is a novel PDCoV Southeast Asia-like strain with distinct genetic characteristics and pathogenicity. This finding enriches the international information on the genetic diversity of PDCoV.

Fecal viral DNA shedding following clinical panleukopenia virus infection in shelter kittens: a prospective, observational study.

ObjectivesThe aims of this study were to determine the magnitude and duration of fecal viral DNA shedding after diagnosis of feline panleukopenia (FP) in a group of shelter cats using quantitative real-time PCR (qPCR); to assess the utility of a negative point-of-care test or the resolution of diarrhea and systemic signs as proxy measures for qPCR positivity; and to investigate patterns of additional enteric pathogens in relation to feline panleukopenia viral shedding duration.MethodsFeline panleukopenia virus (FPV) infection in clinically affected shelter cats was confirmed by a commercial qPCR test. Observations were made on days 0, 3, 7, 14 and 21 post-diagnosis. Fecal flotation, FPV qPCR and the canine parvovirus IDEXX SNAP Parvo ELISA (SNAP) test were performed on fecal samples.ResultsForty cats and kittens with confirmed panleukopenia were initially enrolled. Sixteen kittens were sampled until day 14, and 12 were followed to day 21. Median DNA viral copy numbers fell below the diagnostic cut-off by day 7, with 13/16, 6/16, 1/16 and 0/12 testing PCR-positive on days 3, 7, 14 and 21, respectively. The SNAP test was positive in 12/16 kittens on day 0 and only 3/16 on day 3. SNAP test results, diarrhea and systemic signs were inconsistent in relation to qPCR positivity post-diagnosis. Additional enteric pathogens were common. The presence of additional pathogen types was suggestive of a longer PCR shedding duration, but this was not tested statistically owing to the small sample size.Conclusions and relevanceThese findings suggest that cats should be isolated for at least 14 days after a diagnosis of FP, but that release from isolation after this point is reasonable, in association with a multifaceted infection control strategy. The study findings did not support using SNAP test results, diarrhea or systemic signs as proxy measures for virus shedding.