No Evidence of SARS-CoV-2 Among Flies or Cockroaches in COVID-19 Positive Households

Background:The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in a pandemic of coronavirus disease (COVID-19), which continues to cause infections and mortality worldwide. SARS-CoV-2 is transmitted primarily via the respiratory route and has experimentally been found to be stable on surfaces for multiple days. Flies (Diptera) and other arthropods mechanically transmit several pathogens, including turkey coronavirus. A previous experimental study demonstrated house flies, Musca domestica, can mechanically transmit SARS-CoV-2, but the ability of flies in general to acquire and deposit this virus in natural settings has not been explored. The purpose of this study was to explore the possibility of mechanical transmission of SARS-CoV-2 by peridomestic insects and their potential as a xenosurveillance tool for detection of the virus.Methods:In order to optimize chances of viral detection, flies were trapped in homes where at least one confirmed human COVID-19 case(s) resided. Sticky and liquid baited fly traps were deployed inside and outside of the homes of SARS-CoV-2 human cases in Brazos, Bell, and Montgomery Counties, from June to September 2020. Flies from sticky traps were identified, pooled by taxa, homogenized, and tested for the presence of SARS-CoV-2 RNA using qRT-PCR. Liquid traps were drained, and the collected fluid similarly tested after RNA concentration. Experimental viral detection pipeline and viral inactivation were confirmed in a Biosafety Level 3 lab. As part of a separate ongoing study, companion animals in the home were sampled and tested for SARS-CoV-2 on the same day of insect trap deployment.Results:We processed the contents of 133 insect traps from 44 homes, which contained over 1,345 individual insects of 11 different Diptera families and Blattodea.These individuals were grouped into 243 pools, and all tested negative for SARS-CoV-2 RNA. Dead flies exposed to SARS-CoV-2 in a BSL3 lab were processed using the same methods and viral RNA was detected by RT-PCR. Fourteen traps in seven homes were deployed on the day that cat or dog samples tested positive for SARS-CoV-2 RNA by nasal, oral, body, or rectal samples.Conclusions:This study presents evidence that biting and non-biting flies are not likely to contribute to mechanical transmission of SARS-CoV-2 or be useful in xenosurveillance for SARS-CoV-2.

Infection with Avian Coronaviruses: A recurring problem in turkeys

Turkey coronavirus (TCoV) is a Gammacoronavirus causing acute contagious enteritis in young turkeys, leading to impaired growth, low feed conversion, and increased mortality. The TCoV infections, in association/combination with other enteropathogenic viruses, bacteria & protozoa, are associated with poult enteritis-mortality syndrome (PEMS) in turkeys of 1-4 weeks age. In this review, classification & genotyping of TCoV, the implications of its recombination, and challenges to develop efficient vaccines against it are discussed. Though TCoV is monophyletic with infectious bronchitis virus (IBV) with a sequence similarity of ≥86, however a classification scheme gathering all avian coronaviruses (ACoVs) is not established. Based on the N gene, ACoVs are classified into five clades. Clades 1 & 2 (chickens), Clade 3 (pigeon) Clade 4 (duck), and Clade 5 (goose). The Spike (S) gene of ACoVs has shown exceptional lability of being easily switched with multiple recombination events suggesting that TCoV may be an IBV recombinant. Recombination events altered the pathogenicity, host specificity, and tissue tropism of TCoVs. Attempts to develop attenuated, inactivated, DNA, and virus-vectored vaccines are ongoing. Experimentally, the attenuated TCoV strains induced strong humoral and cellular immune responses and completely protected against the homologous challenge but not heterologous TCoV challenge. Meanwhile, genetically engineered vaccines, either DNA or virus vectored vaccines, are limited with either late induction of a protective immune response and/or inability of the elicited antibody to neutralize virus infection and protect against virus challenge. Future research should focus on improving vaccine efficiency against TCoVs by developing more immunogenic vaccines, determining the appropriate dosing regimens, and include potent adjuvants.

A LITERATURE REVIEW OF NOVEL COVID-19 AND RELATED CORONAVIRUSES OUTBREAKS IN THE 1960S UNTIL 21ST CENTURY

Coronavirus (CoVs) is a large group of viruses known to affect birds and mammals including humans. This review aims to present the types of human coronavirus and animal coronavirus studied and displaying the relationships of these coronaviruses to weather, meteorology and climatology. Human coronaviruses (HCoV) in review are namely 229E, NL63, OC43 and HKU1 and other HCoV which are Severe Acute Respiratory Syndrome (SARS-CoV), Middle East Respiratory Syndrome (MERS-CoV) and COVID-19 (SARS-CoV-2). These HcoV originated as animal infections which then develop and ultimately transmitted to humans. CoV can also be found in animals which are Canine Respiratory Coronavirus (CRCoV), Murine Coronavirus Rat Hepatitis Virus (MHV), Transmissible Gastroenteritis Virus (TGEV), Bovine Coronavirus (BCoV), Feline Coronavirus (FCoV), Canine Coronavirus (CCoV) and Turkey Coronavirus (TCV). CoV has been found to last longer in the atmosphere at lower temperatures and lower relative humidity. Thus, some coronavirus outbreaks can mostly be attributed to cold and dry climates for more effective CoV transmission. Identified CoV are mostly active when the temperature is between 9 °C and 24 °C. Findings in this review can serve as knowledge and guidance for individuals, related organizations and governments to be prepared for the CoV threats that is currently occurring and that is likely to re-emerge in the coming years. It is also intended to provide useful baseline information for policymakers and the public. KEYWORDS: climatology, coronavirus (CoVs), human coronaviruses (HCoV), meteorology, weather

PATHOGENICITY, IMMUNOGENICITY, PROTECTION EFFICACY, AND SPIKE PROTEIN GENE SEQUENCE OF A HIGH-PASSAGE TURKEY CORONAVIRUS SERIALLY PASSAGED IN EMBRYONATED TURKEY EGGS

Experimental infection of a high-passage turkey coronavirus passaged serially in embryonated turkey eggs for 344 times (P344 TCoV 540) showed no enteritis-related clinical signs, decreased body weight gains, gross, and microscopic lesions. TCoV spike (S) protein specific antibodies appeared from 14 days post infection (dpi) and increased gradually. Virus neutralization (VN) titers of the serum from P344 TCoV 540-inoculated turkeys were 1:13 at 14 dpi, 1:16 at 28 dpi, and 1:36 at 56 dpi against P344 TCoV 540. P344 TCoV 540-inoculated turkeys were protected against the challenge by homologous P344 TCoV 540 completely or low passage P3 TCoV 540 partially as revealed by lack of histopathological alterations, absence of TCoV by immunofluorescent antibody assay in the intestines, and reduction in TCoV viral RNA loads in the intestines and feces. The serum from P344 TCoV 540-vaccinated turkeys had higher VN titers against P344 TCoV 540 than those against P3 TCoV 540. P344 TCoV 540 had 52 amino acid substitutions as compared to those of P3 TCoV in the S protein. The results indicated that a high passage TCoV can induce protective humoral and cellular immune response and have potentials to become an attenuated vaccine.