Viral Shedding Research Articles

Recombinant avian-derived antiviral proteins cIFITM1, cIFITM3, and cViperin as effective adjuvants in inactivated H9N2 subtype avian influenza vaccines

Vaccine adjuvants, serving as non-specific immune enhancers, play a pivotal role in the immunoprevention and control of animal diseases. This study utilized prokaryotic expression systems to express and purify chicken-derived cIFITM1, cIFITM3, and cViperin, which were then formulated as adjuvants with H9N2 avian influenza virus antigens to create inactivated vaccines. These vaccines were administered to SPF chickens to investigate their immunopotentiating functions. Additionally, the proteins were assessed for their ability to act as standalone immune enhancers. The results demonstrated that cIFITM1, cIFITM3, and cViperin significantly elevated serum hemagglutination inhibition (HI) antibody titers. Notably, when used individually, these proteins markedly enhanced the antiviral capabilities of challenged chickens, leading to alleviated clinical symptoms, reduced tracheal virus replication, diminished virus shedding, and lessened histopathological damage, with cIFITM1 exhibiting the most pronounced effect. Furthermore, the protective efficacy of two H9N2 recombinant virus inactivated vaccines supplemented with cIFITM1 adjuvant was validated, achieving a 100 % vaccine protection efficiency. In conclusion, cIFITM1, cIFITM3, and cViperin as adjuvants for influenza vaccines effectively inhibit virus replication and shedding, highlighting their significant potential in influenza prevention and control.

Comparative pathogenesis of Ethiopia/Habru/2014 Lineage-IV peste des petits ruminants virus in goats and cattle

BackgroundPeste des Petits Ruminants (PPR) is a highly contagious viral disease primarily affecting goats and sheep, with clinical manifestations ranging from peracute disease to subclinical infection, particularly in atypical hosts such as cattle. The role of atypical hosts such as cattle to the spread of PPR remains controversial, with conflicting reports in the literature. Despite its worldwide significance, considerable knowledge gaps exist regarding the pathogenesis and clinical progression in both primary and atypical hosts. This study aimed to elucidate the tissue tropism, pathogenesis, virus shedding, clinical progression, and pathology associated with experimental PPR virus infection in indigenous goats and cattle. To this end, 32 animals—16 goats and 16 cattle—were intranasally inoculated with the Ethiopia/Habru/2014 Lineage-IV strain of the PPR virus followed by detailed clinical evaluations and systematic sampling at pre-established intervals to assess serological conversion, viral shedding, and the pathogenesis of the infection across both species.ResultsThe results show that goats exhibited typical clinical signs 4 days post-inoculation, with seroconversion by day 6 and early detection of viral RNA in swabs and tissues by day 3 and virus isolation starting day 4. In contrast, cattle exhibited minimal clinical signs, with seroconversion occurring at day 8 with viral RNA detected in tissue samples at day 4 and virus isolation starting day 6 in tissues and in a single nasal swab at day 8. Clinical scores and tissue positivity rates significantly differed between goats and cattle (P = 0.007 and P < 0.001, respectively). While goats exhibited expected gross and histopathological lesions, cattle showed only nonspecific lesions.ConclusionsTogether, our findings highlight the importance of comparative pathology studies for better understanding virus dynamics and transmission pathways that may help inform more effective PPR control programs. Future research should explore the pathogenesis of different PPRV lineages in cattle, assessing variations in disease progression and potential for epidemiological impact.

Comparative pathogenicity of duck hepatitis A virus genotype 3 in different duck breeds: Implications of the diagnosis and prevention of duck viral hepatitis

Duck hepatitis A virus (DHAV) infection in ducklings causes acute hepatitis with considerable economic losses. In this study, Pekin and Muscovy duckling flocks (n=9) suffering from high mortality and hepatic lesions were examined by RT-PCR for DVHA. 44.4 % (4/9) of samples were positive for DHAV (5′ UTR region), of which 100 % (4/4) were DVHA-3 (VP1 gene). VP1 sequencing and phylogenetic analysis of an isolate originated from Muscovy ducklings showed that it shared 96.8 % −100 %, 88.5–89.2 %, and 86.5–88.2 % nucleotide similarity (ns) with the Egyptian, Korean-Vietnamese, and Chinese DVHA-3 strains, respectively. It was distinguished from the DHAV-1 vaccine (67.6 % ns). The sequenced DVHA-3 isolate was used to experimentally infect 5-day-old Pekin and Muscovy ducklings vs. control groups. No apparent clinical signs or deaths were reported in the experimentally-infected groups. Pekin ducklings showed greater cloacal viral shedding than Muscovy until the 6th dpi (P<0.05). DVHA-3 induced a significant rise in IFN-β and IL-1β serum levels, where Muscovy ducklings' levels were higher than Pekin ducklings. Among the biochemical parameters, AST was only increased on the 4th dpi in both breeds vs. control (P<0.05). Compared to Muscovy ducklings at 2, 4, and 6 day post infection (dpi), the infected Pekin group had lower lipase levels (P≥0.05, p<0.05, and p<0.05, respectively), while ALT was higher at 4 and 6 dpi (P<0.05). The histopathological lesions supported the gross lesions, and their scores were dominant at 2 and 4 dpi in both breeds. At 6 and 8 dpi, Pekin showed more severe histopathological changes compared to Muscovy for the liver, heart, brain, and intestines; the pancreas, kidney, and lung showed the opposite pattern. In conclusion, Pekin ducklings displayed distinct DHAV-3 infection results from Muscovy ducklings, and more research utilizing a variety of DHAV-3 strains has to be carried out.

The zoonotic LCK-3110 strain of Rocahepevirus ratti leads to mild infection in chickens after experimental inoculation

Rocahepevirus ratti [rat hepatitis E virus (HEV)] was originally isolated from rats and found to be non-infectious to nonhuman primates, suggesting humans were not a susceptible host. However, in 2018, rat HEV infections were identified in human patients. High seroprevalence for rat HEV in rats in many countries necessitates studying this emerging zoonotic outbreak. Lack of a human derived rat HEV infectious clone, cell culture systems, and animal models have hindered this effort. In response to the increase in human infection cases by rat HEV, we utilized an infectious clone of the zoonotic rat HEV LCK-3110 strain originally reported from human cases. Capped RNA transcripts of the rat HEV LCK-3110 strain were synthesized, and replication was assessed in both cell culture via transfection and chickens via intrahepatic inoculation. Naive chickens were cohoused together with inoculated chickens. Our results demonstrated that although chickens were susceptible, virus replication was inefficient with only a few of the chickens inoculated with rat HEV having low levels of viremia and fecal virus shedding. However, LCK-3110 HEV was able to transmit between chickens as several naive cohoused chickens became infected as evidenced by viremia, fecal shedding, and the presence of viral protein upon histopathology of the liver. Rat HEV is an emerging zoonotic virus with an ability to spillover across species. Chickens have potential to serve as intermediary hosts, possibly playing a role in rat HEV spread and exposure to humans.

The prevalence and shedding of porcine epidemic diarrhea virus in intensive swine farms of China from 2022 to 2023

Porcine epidemic diarrhea has emerged as a significant threat to the global swine industry. The shedding and exposure status of porcine epidemic diarrhea virus (PEDV) in intensive farms is not completely understood. In this study, a total of 56,598 clinical samples collected from 256 intensive pig farms in 20 provinces in China from 2022 to 2023, were evaluated for PEDV using quantitative real-time PCR. The overall PEDV prevalence was 11.78 % and 28.45 % at the sample and farm levels, respectively, which are relatively high in Northern China and the fourth and first quarter of the year. The PEDV-positive rates and viral loads in suckling piglet herds were higher than those in growing-finishing pigs and multiparous sows. Meanwhile, 15.61 % of pig pens, 9.51 % of corridors, 9.4 % of office areas, 9.23 % of production personnel, and 8.33 % of pig cart driver samples were positive for PEDV, indicating potential biosafety gaps in intensive pig farms. In addition, 93.41 % of inguinal lymph node tissue samples contained viral nucleic acids, revealing a possible persistent infection of PEDV in pig herds. Our study presents the first report of the large-scale detection of PEDV in intensive pig farms, which constitutes indirect evidence of virus circulation in pig herds. This study provides valuable data for preventing and controlling PEDV infection in the future.

Impact of early antiviral therapy on SARS-CoV-2 clearance time in high-risk COVID-19 subjects: A propensity score matching study

BackgroundEffective treatments for COVID-19 are needed to mitigate disease progression and reduce the burden on healthcare systems. This study investigates the impact of early treatments on SARS-CoV-2 viral shedding duration among high-risk individuals with mild symptoms. MethodsA single-center, retrospective observational study was conducted at Luigi Sacco Hospital in Milan from December 2021 to March 2023. Hospitalized and nonhospitalized adults with a confirmed SARS-CoV-2 infection and at high-risk of disease progression were enrolled. Unadjusted and adjusted negative binomial regression models and a Random Forest regression model were performed before and after matching subjects based on their propensity of being treated or not. ResultsResults from 518 subjects (428 treated and 90 untreated) revealed a significant reduction in SARS-CoV-2 viral shedding duration among those who received early treatment compared to untreated individuals. Propensity score matching and multivariable regression analyses confirmed this finding. Early treatment significantly reduced the risk of COVID-19-related hospitalization and pneumonia development. Subgroup analysis identified COPD as a potential factor influencing effectiveness of early treatments. ConclusionsEarly treatments play a crucial role in reducing SARS-CoV-2 viral shedding and preventing disease progression among high-risk individuals. Shorter viral shedding duration also contributes to improved healthcare resource utilization and infection control measures.

Efficacy and Safety in Dogs Following Administration of an Alphavirus RNA Particle Canine Influenza H3N2 Vaccine.

Canine influenza virus (CIV) H3N2 causes a highly contagious respiratory disease in dogs and has been the source of outbreaks across North America since 2015. An injectable RNA Particle (RP)-CIV H3N2 vaccine has been developed to protect dogs against this disease. To demonstrate efficacy, dogs were randomized into two treatment groups, then vaccinated subcutaneously twice, 21 days apart, with a placebo vaccine (n = 20) or an RP-CIV H3N2 vaccine (n = 20). Three weeks later, dogs were challenged intranasally with virulent CIV H3N2 and observed daily for 10 days for clinical signs of disease. Nasal swabs were also collected daily to evaluate the shedding of the challenge virus. Ten days post-challenge, the dogs were euthanized, and the lungs were examined for consolidation. RP-CIV H3N2 vaccination demonstrated a significant reduction in the duration of clinical signs, duration and amount of virus shed, lung consolidation, and the incidence of suppurative pneumonia. To evaluate safety, dogs from multiple geographic regions were vaccinated subcutaneously, 3-4 weeks apart, with an RP-CIV H3N2 vaccine and observed for adverse events for 14 days after each administration. The RP-CIV H3N2 vaccine was deemed safe, with lethargy being the most reported adverse event at a rate of 1.6%.

First detection and biological characterization of an avian metaavulavirus 8 isolated from a migratory swan goose in Qinghai Lake, Northwest China.

Avian metaavulavirus 8 (AMAV-8), formerly known as avian paramyxovirus 8 (APMV-8), has been detected sporadically in wild birds worldwide since it was first identified in a Canadian goose in 1976. However, the presence of AMAV-8 in birds has never been reported in China. To understand the epidemiological situation of AMAV-8 and its ability to infect chickens, we conducted a surveillance study and in vivo analysis of the AMAV-8 isolate identified in total of 14,909 clinical samples collected from wild and domestic birds from 2014 to 2022 in China. However, in 2017, only one AMAV-8 virus (Y7) was successful isolated from the fresh droppings of a migratory swan goose in Qinghai Lake in Northwest China. Thereafter, we report the complete genome sequence of the Y7 strain with a genome length of 15,342 nucleotides and the Y7 isolate was genetically closely-related to wild bird-origin AMAV-8 viruses previously circulated in the United States, Japan, and Kazakhstan. Furthermore, AMAV-8 infections of one-day-old specific pathogen-free (SPF) chicks did not induce any clinical signs over the entire observation period but was associated with viral shedding for up to 8 days. Interestingly, although all birds infected with the Y7 strain seroconverted within the first week of infection, virus replication was only detected in the trachea but not in other tissues such as the brain, lung, or heart. Here, we report the complete genome, genetic and biological characterization, replication and pathogenicity analysis in vivo and first detection of AMAV-8 in China.

The glutamate receptor antagonist ifenprodil inhibits hepatitis E virus infection.

Infection with hepatitis E virus (HEV) represents a global problem, with over 20 million people infected annually. No specific antiviral drugs are available for treating HEV infection, necessitating the development of novel targeted therapeutics. Here, we report that the N-methyl-D-aspartate receptor (NMDAR) antagonist ifenprodil, a clinically approved drug used to treat idiopathic pulmonary fibrosis (IPF), is an HEV inhibitor in liver-derived cells. In vitro investigation demonstrates that ifenprodil suppresses viral protein expression in a dose-dependent manner in human hepatoma cells by inhibiting early stages of viral infection. We also found that ifenprodil modulates host cell intrinsic biological processes distinct from virus-induced innate immunity, inhibiting HEV RNA accumulation in primary human hepatocytes. Finally, the inhibitory effect of ifenprodil in vivo was also tested in rabbits challenged with the HEV-3ra CHN-BJ-R14 strain. Fecal virus shedding was below the limit of detection in two animals for both ribavirin-treated and ifenprodil-treated rabbits compared to vehicle-treated control animals. Our data demonstrate that ifenprodil is an effective anti-HEV compound with potential as a therapeutic candidate for the treatment of HEV infection.

Viral load dynamics in asymptomatic and symptomatic patients during Omicron BA.2 outbreak in Shanghai, China, 2022: a longitudinal cohort study

The SARS-CoV-2 virus, particularly the Omicron BA.2 variant, led to a significant surge in Shanghai, 2022. However, the viral load dynamic in Omicron infections with varying clinical severities remain unclear. This prospective cohort included 48,830 hospitalized coronavirus disease 2019 (COVID-19) patients across three hospitals in Shanghai, China, between 23 March and 15 May 2022. Systematic nucleic acid testing was performed using RT-PCR Cycle threshold (Ct) value as a proxy of viral load. We analyzed the kinetic characteristics of viral shedding by clinical severity and identified associated risk factors. The study comprised 31.06% asymptomatic cases, 67.66% mild-moderate cases, 1.00% severe cases, 0.29% critical and fatal cases. Upon admission, 57% of patients tested positive, with peak viral load observed at 4 days (median Ct value 27.5), followed by a decrease and an average viral shedding time (VST) of 6.1 days (Interquartile range, 4.0–8.8 days). Although viral load exhibited variation by age and clinical severity, peak Ct values occurred at similar times. Unvaccinated status, age exceeding 60, and comorbidities including hypertension, renal issues kidney dialysis and kidney transplantation, neurological disorders, rheumatism, and psychotic conditions were found to correlate with elevated peak viral load and extended VST. Asymptomatic cases demonstrated a 40% likelihood of contagiousness within 6 days of detection, while mild-moderate and severe cases exhibited post-symptom resolution infectious probabilities of 27% and over 50%, respectively. These findings revealed that the initial Ct values serve as a predictive indicator of severe outcomes. Unvaccinated elderly individuals with particular comorbidities are at high-risk for elevated viral load and prolonged VST.

Efficacy of the H7N9 vaccine as a candidate for the Korean avian influenza antigen bank

The avian influenza A virus (H7N9), first detected in China in 2013, is a zoonotic virus that remains persistent in bird populations despite a decline in human cases owing to control measures. Therefore, this study aimed to develop a vaccine as one preventive strategy in anticipation of the potential entry of H7N9 into Korea. Using the hemagglutinin and neuraminidase consensus sequences of H7N9 from 2018–2019, a recombinant H7N9 vaccine, rgAPQAH7N9, was developed, and its protective efficacy in specific pathogen-free chickens was evaluated. The rgAPQAH7N9 vaccine exhibited proliferation in eggs and demonstrated high immunogenicity, with a hemagglutination inhibition titer of 9.3 log2. Furthermore, the vaccine provided complete protection, as vaccinated chickens did not exhibit clinical signs or viral shedding. Moreover, when the rgAPQAH7N9 vaccine was boosted, the resulting immunity was long-lasting, with hemagglutination inhibition titers > 7 log2 persisting after 6 months. Therefore, the rgAPQAH7N9 vaccine virus may be considered a potential candidate for inclusion in the avian influenza antigen bank to ensure preparedness for emergency vaccination in poultry.

Hot topic: Avian influenza subtype H5N1 in US dairy—A preliminary dairy foods perspective

In February and March of 2024, an unusual illness began affecting dairy herds primarily in Texas and neighboring states. The causative agent of this illness was ultimately confirmed in late March 2024 to be a strain of highly pathogenic avian influenza H5N1 belonging to clade 2.3.4.4b. In the months following the emergence of this viral disease in cattle, infections have spread to at least 191 herds in 13 states at the time of this writing in August 2024, primarily through cattle and human movement. Surprisingly, early examination of raw milk samples from clinically affected animals indicated that the virus had an affinity for the mammary tissue, and viral shedding into raw milk occurred at high levels, exceeding 108 log10 50% tissue culture infectious dose (TCID50) in some cases. These high viral loads coupled with evidence that farm cats who consumed raw milk from clinically ill animals were infected and exhibited high mortality rates, raised concerns about the safety of the US milk supply for human consumption. To date, 4 cow-associated human infections have been reported, all from farm employees with direct contact with infected animals. Several parameters ultimately affect the theoretical public health risk from consumption of dairy products manufactured from a milk supply containing H5N1, namely (1) initial viral load, (2) persistence of H5N1 in raw milk, (3) viral inactivation through processing practices including pasteurization, and (4) human susceptibility and infectious dose. In the short period since the emergence of this disease in dairy cattle in the United States, research has begun to answer these critical questions, although our knowledge is still quite limited at this time. Here we review the literature available from the current H5N1 outbreak in US dairy cattle, as well as selected relevant literature from previous research in other animal agriculture sectors, that affect our current understanding of the parameters associated with the food safety risk of this disease in the US dairy supply chain.

First isolation of bovine coronavirus with a three-amino-acid deletion in the N gene causing severe respiratory and digestive disease in calve.

Bovine coronavirus (BCoV), a persistent threat to global cattle industry, has caused significant economic losses worldwide. In this study, a viral strain was isolated from the intestinal content of a diseased calve, and identified by cytopathic effects observation, indirect immunofluorescence assay and electron microscopy. Results showed that BCoV NXWZ2310 belonging to the GIIb genotype and has a three-amino-acid deletion in the serine-rich region of the N gene. Importantly, the BCoV NXWZ2310 strain exhibited strong pathogenicity, causing nasal discharge and watery diarrhea in calves for 8 and 10 days, respectively. Viral shedding was detected in nasal, throat and rectal swabs at levels reaching 106.228 copies/mL, 105.0 copies /mL and 106.692 copies/mL, respectively. Pathological examination showed that NXWZ2310 resulted in parenchymal lesions of the pulmonary lobe and significant intestinal lesions. Both the lungs and intestines displayed marked microscopic lesions with clear viral antigens present. BCoV NXWZ2310 strain with N-gene deletion mutations, caused severe respiratory and digestive disease in calves. Therefore, effective strategies are needed for the prevention and control of this isolate.

Hot topic: Influenza A H5N1 virus exhibits a broad host range, including dairy cows

The widespread circulation of highly pathogenic avian influenza (HPAI) H5N1 clade 2.3.4.4b in wild birds in North America since late 2021 has resulted in multiple outbreaks in commercial and backyard poultry leading to major economic losses. Since the emergence of the virus in North America, multiple reassortment events have led to the emergence of many new variant genotypes that have been isolated from wild birds, with several viruses spilling over into poultry and other terrestrial and aquatic mammalian hosts. Notably, the most recent emerging HPAI H5N1 reassortant genotype B3.13 spilled over into dairy cattle (Bos taurus), resulting in unprecedented efficient transmission of the virus in this species, the first case of sustained transmission in a mammalian species. The transmission pathways involved in the spread of the virus from its first detection in Texas to several other states are complex. However, movement of subclinically infected cattle likely played a major role in virus spread. Infection in dairy cattle is characterized by the virus's tropism for milk-secreting cells in the mammary gland, leading to high viral load and shedding in milk. Replication of the virus in milk-secreting cells results in destruction of infected cells leading to severe viral mastitis, which is characterized by marked changes in milk quality (altered consistency and color) and pronounced decline in milk production by clinically affected animals. Here, we provide an overview of the HPAI H5N1 panzootic virus and discuss its host range and the current knowledge of its pathogenesis in the new bovine host.

RpIFN-λ1 alleviates the clinical symptoms of porcine epidemic diarrhea

Porcine epidemic diarrhea (PED), caused by the porcine epidemic diarrhea virus (PEDV), primarily affects the jejunum and ileum of pigs. Interferons, glycoproteins with high species specificity and potent antiviral activity, are crucial in defending against viral infections. Unlike other interferons, interferon-lambda (IFN-λ) mainly acts on mucosal epithelial cells and exhibits robust antiviral activity at mucosal surfaces. However, the high cost limits the use of naturally extracted interferons in farming. In this study, we expressed recombinant porcine interferon-lambda 1 (rpIFN-λ1) in eukaryotic cells, demonstrating effective antiviral activity against PEDV in Vero E6 and IPI-FX cells. In vivo, rpIFN-λ1 alleviated clinical symptoms and intestinal damage, enhanced antioxidant capacity, reduced inflammation, and significantly improved the survival rate of piglets following PEDV infection. Both in vitro and in vivo studies confirmed that rpIFN-λ1 upregulated interferon-stimulated genes (ISGs) via the JAK-STAT pathway, thereby exerting antiviral effects. In conclusion, rpIFN-λ1 significantly inhibited PEDV replication and alleviated clinical symptoms. The selectivity of rpIFN-λ1 for intestinal cells and its ability to reduce viral shedding suggest that this agent is a promising antiviral for enteric viruses such as PEDV. Our findings highlight rpIFN-λ1 as a cost-effective, efficient, and novel strategy for antiviral treatment of PEDV.

Establishment of enterically transmitted hepatitis virus animal models using lipid nanoparticle-based full-length viral genome RNA delivery system

BackgroundEnterically transmitted hepatitis viruses, such as hepatitis A virus (HAV) and hepatitis E virus (HEV), remain notable threats to public health. However, stable and reliable animal models of HAV and...

Effects of vaccination on antibody level and duration of viral shedding in Omicron patients.

We compared the clinical characteristics of vaccinated and non-vaccinated Omicron patients in order to provide a reference for the clinical diagnosis and treatment of coronavirus disease 2019 (COVID-19). This study included 360 patients diagnosed with COVID-19. The serum immunoglobulin G (IgG) and serum immunoglobulin M (IgM) antibody levels of the patients and the duration of virus shedding were analyzed according to age, gender, vaccine dose, and the time from the most recent vaccination to the onset of Omicron infection. Age (OR = 0.974), days from last vaccination to onset ≤ 180 days (OR = 4.409), and booster dose of the vaccine (OR = 4.999) were protective factors associated with patients who were IgG antibody positive. The duration of virus shedding in IgG -antibody-positive patients was 9 (8-11) days; and this was significantly lower than that in IgG-antibody-negative patients, who had virus shedding duration of 10 (8-12) days (p < 0.05). Booster immunizations could increase IgG-antibody in patients who have already been infected with the Omicron variant and enhance immune protection. In addition, COVID-19 vaccination may shorten the duration of virus shedding.

Evaluation of Tembusu virus single-round infectious particle as vaccine vector in chickens

Orthoflaviviruses are single-stranded RNA viruses characterized by highly efficient self-amplification of RNA in host cells, which makes them attractive vehicles for vaccines. Numerous preclinical and clinical studies have demonstrated the efficacy and safety of orthoflavivirus replicon vectors for vaccine development. In this study, we constructed Tembusu virus (TMUV) replicon-based single-round infectious particles (SRIPs) as vaccine development platform. To evaluate the potential of TMUV SRIPs as vaccines, we generated SRIPs that express the heterologous Fowl adenovirus 4 (FAdV-4) fiber2 protein and fiber2 head domain, named TMUVRP-fiber2 and TMUVRP-fiber2H, respectively. To assess the immunogenicity of the TMUV SRIPs, SPF chicks were intramuscularly inoculated twice. Our results showed that the TMUVRP-fiber2 vaccines elicited high levels of neutralizing antibodies. Challenge experiments showed that TMUVRP-fiber2 provided full protection against virulent FAdV-4 and significantly reduced viral shedding. Moreover, the immunogenicity of TMUVRP-fiber2H was significantly lower than that of TMUVRP-fiber2, which was reflected in the neutralizing antibody titer, survival rate, and virus shedding after challenge. Therefore, our results suggested that TMUV SRIPs are a promising novel platform for the development of vaccines for existing and emerging poultry diseases.

Genetic characteristics associated with the virulence of porcine epidemic diarrhea virus (PEDV) with a naturally occurring truncated ORF3 gene

Porcine epidemic diarrhea virus (PEDV) has emerged in American countries, and it has reemerged in Asia and Europe, causing significant economic losses to the pig industry worldwide. In the present study, the 17GXCZ-1ORF3d strain, which has a naturally large deletion at the 172–554 bp position of the ORF3 gene, together with the 17GXCZ-1ORF3c strain, was serially propagated in Vero cells for up to 120 passages. The adaptability of the two strains gradually increased through serial passages in vitro. Genetic variation analysis of the variants of the two strains from different generations revealed that the naturally truncated ORF3 gene in the 17GXCZ-1ORF3d variants was stably inherited. Furthermore, the survival, viral shedding and histopathological lesions following inoculation of piglets demonstrated that the virulence of 17GXCZ-1ORF3d-P120 was significantly attenuated. These results indicate that the naturally truncated ORF3 gene may accelerate the attenuation of virulence and is involved in PEDV virulence together with mutations in other structural genes. Importantly, immunization of sows with G2b 17GXCZ-1ORF3d-P120 increased PEDV-specific IgG and IgA antibody levels in piglets and conferred partial passive protection against heterologous G2a PEDV strains. Our findings suggest that an attenuated strain with a truncated ORF3 gene may be a promising candidate for protection against PEDV.

Vaccines efficacy against infection with circulating feline calicivirus after one single injection: Comparison of Leucofeligen™ FeLV/RCP and Purevax™ RCPFeLV vaccines

Feline calicivirus (FCV) is a worldwide pathogen that affects the general health status of cats. The aim of this study was to assess the efficacy of the FCV component of two multivalent commercial vaccines after one injection. The cats assigned to the vaccinated groups received one subcutaneous injection of either the Leucofeligen™ FeLV/RCP (Virbac, France) vaccine or the Purevax™ RCPFeLV (Boehringer Ingelheim, Germany) vaccine. In the control group, the cats did not receive any vaccine. Three weeks after the vaccine injection, all the cats were inoculated with a heterologous calicivirus strain, isolated in the field. The clinical signs of calicivirosis and the viral shedding were assessed. The results demonstrated that Leucofeligen™ FeLV/RCP could protect kittens against FCV infection by reducing clinical signs and viral excretion from 3 weeks after the first injection of primary vaccination, whereas Purevax™ RCPFeLV couldn't offer the same level of protection in similar experimental conditions.