scholarly journals Pathogenicity of H5N8 High Pathogenicity Avian Influenza Virus in Chickens and Ducks from South Korea in 2020–2021

Viruses ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1903
Author(s):  
Min-Ji Park ◽  
Ra Mi Cha ◽  
Soo-Jeong Kye ◽  
Yu-Na Lee ◽  
Na-Yeong Kim ◽  
...  
Keyword(s):  
Avian Influenza ◽  
South Korea ◽  
Clinical Symptoms ◽  
Transmission Rate ◽  
Lethal Dose ◽  
Winter Season ◽  
Virus Shedding ◽  
Viral Shedding ◽  
Death Time ◽  
High Pathogenicity

During the 2020–2021 winter season, an outbreak of clade 2.3.4.4b H5N8 high pathogenicity avian influenza (HPAI) virus occurred in South Korea. Here, we evaluated the pathogenicity and transmissibility of A/mandarin duck/Korea/H242/2020 (H5N8) (H242/20(H5N8)) first isolated from this outbreak in specific pathogen-free (SPF) chickens and commercial ducks in comparison with those of A/duck/Korea/HD1/2017(H5N6) (HD1/17(H5N6)) from a previous HPAI outbreak in 2017–2018. In chickens, the 50% chicken lethal dose and mean death time of H242/20(H5N8) group were 104.5 EID50 and 4.3 days, respectively, which indicate less virulent than those of HD1/17(H5N6) (103.6 EID50 and 2.2 days). Whereas, chickens inoculated with H242/20(H5N8) survived longer and had a higher titer of viral shedding than those inoculated with HD1/17(H5N6), which may increase the risk of viral contamination on farms. All ducks infected with either HPAI virus survived without clinical symptoms. In addition, they exhibited a longer virus shedding period and a higher transmission rate, indicating that ducks may play an important role as a silent carrier of both HPAI viruses. These results suggest that the pathogenic characteristics of HPAI viruses in chickens and ducks need to be considered to effectively control HPAI outbreaks in the field.

scholarly journals Transmission dynamics of the delta variant of SARS-CoV-2 infections in Daejeon, South Korea

2021 ◽  
Author(s):  
Hari Hwang ◽  
Jun-Sik Lim ◽  
Sun-Ah Song ◽  
Chiara Achangwa ◽  
Woobeom Sim ◽  
...  
Keyword(s):  
South Korea ◽  
Symptom Onset ◽  
Credible Interval ◽  
Transmission Dynamics ◽  
Contact Tracing ◽  
Nasopharyngeal Swab ◽  
Strict Adherence ◽  
Virus Shedding ◽  
Viral Shedding ◽  
Asymptomatic Patients

Abstract Background The delta variant of SARS-CoV-2 is now the predominant variant worldwide. However, its transmission dynamics remain unclear. Methods We analyzed all case patients in local clusters and temporal patterns of viral shedding using contact tracing data from 405 cases associated with the delta variant of SARS-CoV-2 between 22 June and 31 July 2021 in Daejeon, South Korea. Results Overall, half of the cases were aged under 19 years, and 20% were asymptomatic at the time of epidemiological investigation. We estimated the mean serial interval as 3.26 days (95% credible interval 2.92, 3.60), and 12% of the transmission occurred before symptom onset of the infector. We identified six clustered outbreaks, and all were associated with indoor facilities. In 23 household contacts, the secondary attack rate was 63% (52/82). We estimated that 15% (95% confidence interval, 13–18%) of cases seeded 80% of all local transmission. Analysis of the nasopharyngeal swab samples identified virus shedding from asymptomatic patients, and the highest viral load was observed two days after symptom onset. The temporal pattern of viral shedding did not differ between children and adults (P = 0.48). Conclusions Our findings suggest that the delta variant is highly transmissible in indoor settings and households. Rapid contact tracing, isolation of the asymptomatic contacts, and strict adherence to public health measures are needed to mitigate the community transmission of the delta variant.

Variation in Viral Shedding Patterns between Domestic and Wild Terrestrial Birds Infected Experimentally with Reassortant Avian Influenza Virus (H9N2)

2016 ◽  
Vol 9 (3) ◽  
pp. 200-206 ◽  
Author(s):  
Sajid Umar ◽  
Sajjad Asif ◽  
Muhammad Usman ◽  
Muhammad Atif ◽  
Shahzad Ali ◽  
...  
Keyword(s):  
Avian Influenza ◽  
Japanese Quail ◽  
Current Knowledge ◽  
Clinical Signs ◽  
Passer Domesticus ◽  
Guinea Fowl ◽  
The Novel ◽  
House Sparrows ◽  
Virus Shedding ◽  
Viral Shedding

Avian influenza (H9N2) virus infection is an emerging respiratory problem and its prevalence varies significantly among different species of birds. The current knowledge about virus shedding parameters in terrestrial birds is limited. With this in mind, the present study was conducted in different domestic and wild terrestrial birds to investigate species-related differences in infectivity and pattern of viral shedding associated with H9N2 AI virus. Groups of terrestrial birds (domestic Guinea Fowl Numida meleagridis, Japanese Quail Coturnix coturnix japonica, House Sparrows Passer domesticus, House Crows Corvus splendens and Bank Myna Acridotheres ginginianus) were inoculated intra-nasally with A/chicken/Pakistan/10RS3039-284-48/2010 (H9N2) AI virus (106 EID50) and then examined for infectivity and virus shedding patterns. With the exception of House Crows, all infected birds showed clinical signs of different severity, showing the most prominent disease signs in Japanese Quail. All infected birds showed positive results for virus shedding, however, the pattern of virus shedding was different among wild terrestrial birds. Japanese Quail showed the highest levels of virus shedding while samples collected from House Crows revealed only very low levels. Interestingly, virus shedding was observed predominantly via the gastrointestinal tract in House Sparrows and Bank Myna and via the buccal cavity route in Guinea Fowl and Japanese Quail. Here we investigated that the novel genotype of H9N2 AI virus circulating in Pakistan causes clinical disease signs in domestic and wild terrestrial birds. The results of this study suggest that virus shedding varies between different related avian species and highlights the potential role of Guinea Fowl, Japanese Quail, House Sparrows and Bank Myna as mixing bowls for the transmission and maintenance of H9N2 AI viruses between premises.

scholarly journals Isolation and Pathogenic Characterization of Pigeon Paramyxovirus Type 1 via Different Inoculation Routes in Pigeons

2021 ◽  
Vol 7 ◽  
Author(s):  
Han Chang ◽  
Shengyong Feng ◽  
Yutian Wang ◽  
Fuhuang Li ◽  
Qianqian Su ◽  
...  
Keyword(s):  
Virus Titer ◽  
Negative Control ◽  
Tissue Tropism ◽  
Type I ◽  
Virus Shedding ◽  
Viral Shedding ◽  
Death Time ◽  
Wide Range ◽  
Pandemic Threat ◽  
Beijing China

Pigeon paramyxovirus type I (PPMV-1) causes regular outbreaks in pigeons and even poses a pandemic threat among chickens and other birds. The birds infected with PPMV-1 mainly show a pathological damage in the respiratory system, digestive system, and nervous system. However, there were few reports on the efficiency of the virus entering the host via routes of different systems. In the present study, a PPMV-1 strain was obtained from a dead wild pigeon in 2016 in Beijing, China. The mean death time (MDT) and the intracerebral pathogenicity (ICPI) of our isolate showed medium virulence. Phylogenetic analysis based on F gene sequence showed that the isolate belonged to subgenotype VIb, class II, which dominated in China in recent years. Then, we evaluated the infection efficiency of different routes. Pigeons were randomly divided into five groups of six as follows: intracephalic (IC), intranasal (IN), and intraoral (IO) infection routes, cohabitation infection (CO), and negative control (N negative). All pigeons were inoculated with 100 μl·106 EID50 PPMV-1 virus. After infection, pathological lesions, virus shedding, body weight change, survival rate, and tissue tropism were tested to compare the efficiency of the different infected routes. The mortality of groups IC, IN, IO, and CO were 100, 66.7, 50, and 33.3%, respectively. Weight loss in group IC was higher than the other groups, followed by groups IN and IO. The lesions observed in PPMV-1-infected pigeons were severe, especially in the lung and intestine in group IC. Viral shedding was observed from 2 dpi in groups IC and IN, but the shedding rate was higher in group IN than group IC. The longest period was in group CO. Tissue tropism experiment showed that our isolate has a wide range of tissue distribution, and the virus titer in the heart and intestine of group IC and in the brain of group IN was higher. Our data may help us to evaluate the risk of transmission of PPMV-1.

scholarly journals Genetic Characterization and Pathogenesis of Three Novel Reassortant H5N2 Viruses in South Korea, 2018

Viruses ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2192
Author(s):  
Anh Thi Viet Nguyen ◽  
Vui Thi Hoang ◽  
Haan Woo Sung ◽  
Seon-Ju Yeo ◽  
Hyun Park
Keyword(s):  
Avian Influenza ◽  
South Korea ◽  
Mdck Cells ◽  
Winter Season ◽  
Influenza Viruses ◽  
Avian Influenza Viruses ◽  
Potential Threat ◽  
Phylogenetic Tree Analysis ◽  
Wild Duck ◽  
Bean Goose

The outbreaks of H5N2 avian influenza viruses have occasionally caused the death of thousands of birds in poultry farms. Surveillance during the 2018 winter season in South Korea revealed three H5N2 isolates in feces samples collected from wild birds (KNU18-28: A/Wild duck/South Korea/KNU18-28/2018, KNU18-86: A/Bean Goose/South Korea/KNU18-86/2018, and KNU18-93: A/Wild duck/South Korea/KNU18-93/2018). Phylogenetic tree analysis revealed that these viruses arose from reassortment events among various virus subtypes circulating in South Korea and other countries in the East Asia–Australasian Flyway. The NS gene of the KNU18-28 and KNU18-86 isolates was closely related to that of China’s H10N3 strain, whereas the KNU18-93 strain originated from the H12N2 strain in Japan, showing two different reassortment events and different from a low pathogenic H5N3 (KNU18-91) virus which was isolated at the same day and same place with KNU18-86 and KNU18-93. These H5N2 isolates were characterized as low pathogenic avian influenza viruses. However, many amino acid changes in eight gene segments were identified to enhance polymerase activity and increase adaptation and virulence in mice and mammals. Experiments reveal that viral replication in MDCK cells was quite high after 12 hpi, showing the ability to replicate in mouse lungs. The hematoxylin and eosin-stained (H&E) lung sections indicated different degrees of pathogenicity of the three H5N2 isolates in mice compared with that of the control H1N1 strain. The continuing circulation of these H5N2 viruses may represent a potential threat to mammals and humans. Our findings highlight the need for intensive surveillance of avian influenza virus circulation in South Korea to prevent the risks posed by these reassortment viruses to animal and public health.

scholarly journals Re-Invasion of H5N8 High Pathogenicity Avian Influenza Virus Clade 2.3.4.4b in Hokkaido, Japan, 2020

Viruses ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 1439
Author(s):  
Norikazu Isoda ◽  
Augustin T. Twabela ◽  
Enkhbold Bazarragchaa ◽  
Kohei Ogasawara ◽  
Hirotaka Hayashi ◽  
...  
Keyword(s):  
Avian Influenza ◽  
Phylogenetic Trees ◽  
Bird Migration ◽  
Migratory Birds ◽  
Winter Season ◽  
Northern Territory ◽  
Global Level ◽  
Eastern Asia ◽  
High Pathogenicity ◽  
Antigenic Cartography

Global dispersion of high pathogenicity avian influenza (HPAI), especially that caused by H5 clade 2.3.4.4, has threatened poultry industries and, potentially, human health. An HPAI virus, A/northern pintail/Hokkaido/M13/2020 (H5N8) (NP/Hok/20) belonging to clade 2.3.4.4b, was isolated from a fecal sample collected at a lake in Hokkaido, Japan where migratory birds rested, October 2020. In the phylogenetic trees of all eight gene segments, NP/Hok/20 fell into in the cluster of European isolates in 2020, but was distinct from the isolates in eastern Asia and Europe during the winter season of 2017–2018. The antigenic cartography indicates that the antigenicity of NP/Hok/20 was almost the same as that of previous isolates of H5 clade 2.3.4.4b, whereas the antigenic distances from NP/Hok/20 to the representative strains in clade 2.3.4.4e and to a strain in 2.3.4 were apparently distant. These data imply that HPAI virus clade 2.3.4.4b should have been delivered by bird migration despite the intercontinental distance, although it was not defined whether NP/Hok/20 was transported from Europe via Siberia where migratory birds nest in the summer season. Given the probability of perpetuation of transmission in the northern territory, periodic updates of intensive surveys on avian influenza at the global level are essential to prepare for future outbreaks of the HPAI virus.

scholarly journals Virus shedding kinetics and unconventional virulence tradeoffs

2021 ◽  
Vol 17 (5) ◽  
pp. e1009528
Author(s):  
Andrew R. Wargo ◽  
Gael Kurath ◽  
Robert J. Scott ◽  
Benjamin Kerr
Keyword(s):  
Transmission Rate ◽  
Empirical Studies ◽  
Host Population ◽  
Virus Shedding ◽  
Viral Shedding ◽  
Fitness Advantage ◽  
Infectious Hematopoietic Necrosis ◽  
Host Mortality ◽  
The Impact

Tradeoff theory, which postulates that virulence provides both transmission costs and benefits for pathogens, has become widely adopted by the scientific community. Although theoretical literature exploring virulence-tradeoffs is vast, empirical studies validating various assumptions still remain sparse. In particular, truncation of transmission duration as a cost of virulence has been difficult to quantify with robust controlled in vivo studies. We sought to fill this knowledge gap by investigating how transmission rate and duration were associated with virulence for infectious hematopoietic necrosis virus (IHNV) in rainbow trout (Oncorhynchus mykiss). Using host mortality to quantify virulence and viral shedding to quantify transmission, we found that IHNV did not conform to classical tradeoff theory. More virulent genotypes of the virus were found to have longer transmission durations due to lower recovery rates of infected hosts, but the relationship was not saturating as assumed by tradeoff theory. Furthermore, the impact of host mortality on limiting transmission duration was minimal and greatly outweighed by recovery. Transmission rate differences between high and low virulence genotypes were also small and inconsistent. Ultimately, more virulent genotypes were found to have the overall fitness advantage, and there was no apparent constraint on the evolution of increased virulence for IHNV. However, using a mathematical model parameterized with experimental data, it was found that host culling resurrected the virulence tradeoff and provided low virulence genotypes with the advantage. Human-induced or natural culling, as well as host population fragmentation, may be some of the mechanisms by which virulence diversity is maintained in nature. This work highlights the importance of considering non-classical virulence tradeoffs.

scholarly journals Genetic Characteristics of Avian Influenza Virus Isolated from Wild Birds in South Korea, 2019–2020

Viruses ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 381
Author(s):  
Eun-Jee Na ◽  
Young-Sik Kim ◽  
Sook-Young Lee ◽  
Yoon-Ji Kim ◽  
Jun-Soo Park ◽  
...  
Keyword(s):  
Avian Influenza ◽  
South Korea ◽  
Basic Amino Acid ◽  
Histopathological Change ◽  
Amino Acid Sequences ◽  
Wild Birds ◽  
Influenza Viruses ◽  
Economic Losses ◽  
Active Monitoring ◽  
Genetic Characteristics

Wild aquatic birds, a natural reservoir of avian influenza viruses (AIVs), transmit AIVs to poultry farms, causing huge economic losses. Therefore, the prevalence and genetic characteristics of AIVs isolated from wild birds in South Korea from October 2019 to March 2020 were investigated and analyzed. Fresh avian fecal samples (3256) were collected by active monitoring of 11 wild bird habitats. Twenty-eight AIVs were isolated. Seven HA and eight NA subtypes were identified. All AIV hosts were Anseriformes species. The HA cleavage site of 20 representative AIVs was encoded by non-multi-basic amino acid sequences. Phylogenetic analysis of the eight segment genes of the AIVs showed that most genes clustered within the Eurasian lineage. However, the HA gene of H10 viruses and NS gene of four viruses clustered within the American lineage, indicating intercontinental reassortment of AIVs. Representative viruses likely to infect mammals were selected and evaluated for pathogenicity in mice. JB21-58 (H5N3), JB42-93 (H9N2), and JB32-81 (H11N2) were isolated from the lungs, but JB31-69 (H11N9) was not isolated from the lungs until the end of the experiment at 14 dpi. None of infected mice showed clinical sign and histopathological change in the lung. In addition, viral antigens were not detected in lungs of all mice at 14 dpi. These data suggest that LPAIVs derived from wild birds are unlikely to be transmitted to mammals. However, because LPAIVs can reportedly infect mammals, including humans, continuous surveillance and monitoring of AIVs are necessary, despite their low pathogenicity.

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